raid and its associate

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What is RAID?

RAID (Redundant Array of Independent Disks) is a set of technologystandards for teaming disk drives to improve fault tolerance andperformance.

RAID Levels

Level Name

0 Striping

1 Mirroring

2 Parallel Access with Specialized Disks

3 Synchronous Access with Dedicated Parity Disk

4 Independent Access with Dedicated Parity Disk

5 Independent Access with Distributed Parity6 Independent Access with Double Parity

Choosing a RAID Level

Each RAID level represents a set of trade-offs between performance,redundancy, and cost.

RAID 0 -- Optimized for Performance

RAID 0 uses striping to write data across multiple drives simultaneously.This means that when you write a 5GB file across 5 drives, 1GB of data is

written to each drive. Parallel reading of data from multiple drives can havea significant positive impact on performance.The trade-off with RAID 0 is that if one of those drives fail, all of your data islost and you must retore from backup.RAID 0 is an excellent choice for cache servers, where the actual data beingstored is of little value, but performance is very important.

What is striping?

Striping is the automated process of writing data across multiple drives

simulteneously. Striping is used to increase the performance of disk reads.When using striping, if you write a 5GB file across 5 drives, 1GB of data iswritten to each drive. Parallel reading of data from multiple disks can have asignificant positive impact on performance, because the physical disk driveis most often the performance bottleneck.Striping is used in RAID Level 0.

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If one drive in a striped set fails, all of the data in the stripe set is lost. Thedata must be restored from backup. Because of this, striping is oftencombined with the use of parity (RAID 5) or mirroring (RAID 0+1).

Performance Problems Cause by Striping

Striping, when combined with parity, can have a negative performanceimpact on write operations. This is because some of the data used tocalculate parity may be stored on the disk already. This means that theprocess to write to the array is:

1. Read the existing data2. Calculate the parity3. Write the new parity4. Write the new data

RAID 1 -- Optimized for Redundancy

RAID 1 uses mirroring to write data to multiple drives. This means thatwhen you write a file, the file is actually written to two disks. If one of thedisks fails, you simply replace it and rebuild the mirror.The tradeoff with RAID 1 is cost. With RAID 1, you must purchase doublethe amount ofstorage space that your data requires.

What is mirroring?

Mirroring is the automated process of writing data to two drivessimulteneously. Mirroring is used to provide redundancy.If one drive fails, the redundant drive will continue to store the data andprovide access to it. The failed drive can then be replaced and the drive setcan be re-mirrored.Mirroring is used in RAID Level 1.

Software Mirroring vs. Hardware Mirroring

Disk mirroring can be implemented entirely in software. Software mirroringcan be less expensive, but it is also slower. Software mirroring requires the

host computer to write the mirrored data twice.Disk mirroring can be implemented in hardware on the host I/O controller.The burden of writing each bit of data twice is placed upon the I/Ocontroller, which is specifically designed for it.Disk mirroring can also be implemented in hardware on an external storagedevice, such as a RAID array. In this case, mirroring is completely removedfrom the hosts responsibility.

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Hot Swappable Hardware

If the hardware is hot swappable, it is possible to replace a failed diskwithout powering off the computer. You take out the old drive and put in thenew drive with no service outage.

If the hardware does not support hot-swap, you must schedule a serviceoutage, shut down and power-off the system, and then replace the drive.

Mirroring vs. Duplexing

Mirroring is the technique of using redundant disks. Duplexing is mirroring,with the addition of redundant host I/O controllers.If you are using mirroring and your host I/O controller fails, you will not beable to access your data until you replace the host I/O controller. Withduplexing, your data will still be available through the redundant controller.

RAID 5 -- A Good CompromiseRAID 5 stripes data across multiple disks. RAID 5, however, adds a paritycheck bit to the data. This slightly reduces available disk capacity, but it alsomeans that the RAID array continues to function if a single disk fails. In theevent of a disk failure, you simply replace the failed disk and keep going.The tradeoffs with RAID 5 are a small performance penalty in writeoperations and a slight decrease in usabable storage space.

RAID 0+1 -- Optimize for Performance and Redundancy

RAID 0+1 combines the performance of RAID 0 with the redundancy ofRAID 1.To build a RAID 0+1 array, you first build a set of RAID 1 mirrored disks andyou then combine these disk sets in a RAID 0 striped array.A RAID 0+1 array can survive the loss of one disk from each mirrored pair.RAID 0+1 cannot survive the loss of two disks in the same mirrored pair.

What is ATA?

ATA (AT Attachment) is the primary standard for connecting storage to PC's.ATA replaced earlier technologies such as MFM, RLL, and ESDI. ATAcurrently competes with SCSI.ATA is a specification for attaching hard drives to the AT bus. The ATspecification has been extended to include other storage, such as CD/DVDdrives, tape drives, and Zip drives with the Advanced TechnologyAttachment Packet Interface (ATAPI) additions to the specification.ATA is also known as IDE (Integrated Drive Electronics).

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Parallel ATA Cables

Parallel ATA cables originally had 40 wires.With the introduction of ATA-5, parallel ATA cables with 80 wires becamestandard.

Only 40 wires are used to carry signals. The additional 40 wires exist toprovide a ground wire for each signal wire.These grounding wires enable the ATA subsystem to operate at higherspeeds with greater reliability.

ATA Masters and Slaves

Each ATA bus supports two storage devices. The first storage device is

called the Master and the second storage device is termed the Slave.There are two methods for configuring which device is the master and whichis the slave: drive jumpers and cable select.

Drive Jumpers

The original method for configuring Master and Slaverelationships on ATA drives was to place or remove jumpers oneach storage device.The jumper definitions differ among drive manufacturers andmodels. The jumper setting are often printed on the drive. Ifnot, read the drive manual or visit the drive manufacturers webpage.

In a single drive configuration, some drives should be set to"Single Drive", while other drives should be set to "Master".In a dual drive configuration, one drive should be set to Masterand the other drive should be set to Slave.

Cable Select

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A newer standard for configuring Master/Slave relationships onATA drives is to allow the position of the drives on the drivecable to determine the ordering.For Cable Select to work, both of the drives and the ATA cablemust support cable select.To use Cable Select, the jumpers on both drives should be setto Cable Select.

Parallel ATA vs. Serial ATA

All versions of ATA up until ATA-7 in 2004 utilized parallel transfer of datafrom the motherboard to the drive controller built onto the disk.The ATA-7 specification introduced Serial ATA.The most obvious change with Serial ATA is the difference in drive cables.Other differences include:

Higher throughput Revised power connector Longer data cables Support for external drives (eSata)

What is ATAPI?

ATAPI stands for AT Attachment Packet Interface.ATAPI is a set of extensions to the ATA standards to allow ATA CD/DVDdrives and tape drives.

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The ATAPI standard was originally defined by the Small Form Factorcommittee. Maintenance of the ATAPI standard was later transferred to theT13 Technical Committee, the group that defines the ATA standard. TheATAPI standard ceased to exist as a separate document when it becamepart of the core ATA standard with the publication of ATA-4 in 1998.

ATAPI Drivers

Microsoft Windows and most PC-based Unixes provide a generic driver for allATAPI based CD-ROM devices.Because of this, you do not need to download and install an ATAPI driver ifyou are using one of those operating systems.Early ATAPI CD-ROM drives required specialized drivers for use under DOS.If you are running DOS, visit the web page of the company whichmanufactured your CD-ROM drive to try to find an ATAPI driver.

Booting from an ATAPI Device

Phoenix Technologies and IBM developed the El Torito Bootable CD-ROMFormat Specification.Systems which are El Torito compatible are able to boot from ATAPI CD-ROM drives.

What is Serial ATA?

Serial ATA is an enhancement to the ATA standard for for connectingstorage to PC's.All versions of ATA up until ATA-7 in 2004 utilized parallel transfer of datafrom the motherboard to the drive controller built onto the disk.The ATA-7 specification introduced Serial ATA.

Serial ATA Standards

The original Serial ATA standard offered miniminal improvement over theexisting 133MBps bandwidth of the existing Parallel ATA standard.Serial ATA standards are constantly evolving to meet higher bandwidthrequirements.

Serial ATA Type Bandwith Bus Speed Signal Rate

SATA-150 150MBps 1500MHz 1.5Gbps



Serial ATA Data Cables

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Higher bandwidth requirements were pushing requirements for shorterParallel ATA data cables. Serial ATA reversed this trend by allowing datacables up to 1 meter in length.eSATA (External SATA) allows the use of shielded cables up to 2 meters inlength for external drives.

Serial ATA Power Cables

The serial ATA power cable uses a 15-pin wafer connector to provide 3.3, 5,or 12 volts to ATA devices.

Serial ATA Power Cables

The serial ATA power cable uses a 15-pin wafer connector to provide 3.3, 5,or 12 volts to ATA devices.

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What is eSATA?

eSATA is an extension to Serial ATA standards to enable SATA drives to beattached externally.Before eSATA, external hard drives were connected via USB or FireWire.eSATA can provide data transfer rates significantly faster than USB orFireWire.eSATA 1.5 offers data rates up to 150MBps. eSATA 3G doubles that to

300MBps.eSATA cables can be up to 2 meters (approximately 6 feet) in length.eSATA drives are hot-pluggable, meaning that you can attach or remove aneSATA hard drive from a system without powering down the system or thedrive.

What is SCSI?

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SCSI (Small Computer System Interface) is a set of ANSI standards forconnecting devices to computer systems. The vast majority of SCSI devicesare data storage devices.Standard SCSI is a parallel technology, but many serial SCSI variants exist,including FireWire and Fibre Channel.SCSI is generally considered a higher-end alternative to IDE (IntegratedDrive Electronics). A single IDE controller can control two drives. A singleSCI controller can control 8 or 16 drives. In addition, SCSI usually offersgreater cable length and higher length than IDE.

SCSI Standards

SCSI StandardCable

LengthSpeed(MBps)

DevicesSupported

SCSI-1 6 5 8

SCSI-2 6 5-10 8 or 16

Fast SCSI-2 3 10-20 8

Wide SCSI-2 3 20 16

Fast Wide SCSI-2 3 20 16

Ultra SCSI-3,8-bit 1.5 20 8

Ultra SCSI-3,16-bit 1.5 40 16

Ultra-2 SCSI 12 40 8

Wide Ultra-2 SCSI 12 80 16

Ultra-3 (Ultra160/m)SCSI

12 160 16

Narrow and Wide SCSI

Many SCSI standards have options for Narrow or Wide operation. NarrowSCSI is parallel SCSI which transmits 8 bits of data at a time. Wide SCSI isparallel SCI which transmits 16 bits of data at a time.

What is iSCSI?

iSCSI stands for internet SCSI, or internet Small Computer SystemsInterface.iSCSI is the transmission ofSCSI commands and data over IP networks.

How iSCSI Works

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When an application attempts to read from an iSCSI device, the SCSI readcommand is encapsulated inside an IP packet. The IP packet is then routedjust like any other IP packet on the network. When the IP packet reaches itsdestination, the encapsulation is stripped off and the SCSI read command isinterpreted by the iSCSI drive.SCSI write commands are handled in the same manner.

Alternatives to iSCSI

The main competitor to iSCSI is FCIP (Fibre Channel over IP).iSCSI and FCIP represent almost opposite approaches to the situation.FCIP is an implementation of IP on Fibre Channel hardware, whereasiSCSI is an implementation of SCSI on IP hardware.

What is an external hard drive?

An external hard drive is any hard drive which attaches to a port on theoutside of a computer case.External hard drives are extremely useful for backing up computers and formoving data between computers.

External Hard Drive Interfaces

External hard drives can be connected using several popular interfaces. Oneexternal hard drive may support two or more of these interfaces.

FireWire

FireWire, almost known as IEEE 1394, is a popular interface for Macintoshexternal hard drives, and became somewhat popular on PC's before USB 2.0was standardized.

USB

USB (Universal Serial Bus) is a standard for connecting a wide range ofdevices, including external hard drives, PDA's, and Sony PlayStations.USB 1.x was not fast enough to satisfy most users of external hard drives.USB 2.0 provides slightly better performance than FireWire in mostapplications.

eSATA

eSATA is the newest standard for external hard drives.eSATA is an extension of the Serial ATA standard which allows the use ofexternal hard drives.An external hard drive using an eSATA connection will not suffer aperformance penalty imposed by encapsulating the ATA data inside the USBor FireWire protocols, because the eSATA external hard drive uses the samecommunications protocol as the internal hard drives.

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Ethernet

A few external hard drives offer Ethernet connections.These drives include intelligent electronics to enable them to act like fileservers.These external hard drives are actually low-end network attached storagedevices.

What is LBA?

LBA is Logical Block Addressing.Early PC hard drives were supported by the PC BIOS usingCylinder/Head/Sector addressing.To read or write from a specific sector on the disk, you specified the sectorin terms of its cylinder number, its head number, and its sector number.LBA adressing uses just one number. In LBA addressing, the first sector onthe disk is sector zero and all sectors on the disk are simply incrementedfrom there.

What is the MBR?

The MBR is the Master Boot Record.The MBR is a small program which runs whenever a computer boots up.The MBR is stored in the first sector of the boot disk.The boot disk may be a hard drive, a floppy drive, or even a CD or DVDdrive.

The Task of the MBR

The normal job of the MBR program is to search the partition table for theactive partition, copy the boot sector from the active partition into memory,and transfer control over to that program.If the MBR cannot accomplish this task successfully, it will print one of theseerror messages:

Invalid partition table Error loading operating system Missing operating system

The MBR and Boot Sector Viruses

Some boot sector viruses overwrite the MBR.If you believe this has happened to one or more of your disk, run an anti-virus tool to clean your disks.

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FDISK /MBR

Under DOS and early versions of Microsoft Windows, it was possible to usethe `FDISK /MBR` command to repair the MBR.Unfortunately, FDISK was not terribly intelligent about the repair and this

option would often cause more damage than it fixed. FDISK has beenremoved Windows XP.

FIXMBR

Microsoft Windows 2000/XP/2003 provide the `FIXMBR` command in theRecovery Console.The `FIXMBR` command replicates the functionality of the `FDISK /MBR`command, along with it's associated problems.Before attempting to repair your MBR, be certain to completely back up allof your data.

What is a NAND Drive?

NAND drives are high-capacity, high-speed, solid-state flash memory drives.Thanks to new advances in technology, these drives have been chosen tobecome the latest drive preference for laptop computers (hopefully in thenear future). When comparing the NAND to other types of flash memory,NAND drives have several noteworthy advantages.The term "NAND" refers to the architecture of the chip which differs it fromNOR (NOT OR) flash memory. NOR flash memory is most widely used indevices in which small programs are executed in place rather than written toRandom Access Memory (RAM). PDAs, cell phones, and similar devicesfunction with the help of NOR flash memory. NOR flash memory isconsidered to be ideal for applications that require less memory and performmost of the work on unchanging code (for example, boot directions oroperating systems).However, for changing data, NAND drives are superior to NOR flashmemory. The chip is designed to allow more memory to be included into thesame size space, thus creating a product that is not only useful, but alsovery efficient. This allows NAND drives to write data into the disk at agreater speed, unlike the typical flash memory that must wipe out memoryblocks before writing to them. NAND drives also boast a longer lifespan ofmore erase cycles. These features make NAND drives an ideal choice for

high capacity storage and manipulation of changing data.NAND drives also have several noted advantages when compared with moretraditional hard drives. The solid-state nature of the drive is one of the coreadvantages. Solid-state refers to the fact that NAND drives do not have anymoving parts that can break down. Secondly, NAND drives function muchfaster than traditional hard drives. Similar to USB flash drives, NAND drivesdo not make any noise while functioning. Finally, NAND drives consume lesspower, which is essential for laptop users.

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What is a Memory Stick?

A Memory Stick is an IC (Integrated Circuit) which is stored in a compactand rugged plastic enclosure. Memory Sticks are designed to store data andto enable the transfer of data between devices equipped with Memory Stickslots.The Memory Stick standard was introduced by Sony in October of 1998.Current Memory Stick capacities range up to 512MB.A Memory Stick is 50mm long, 21.5mm wide, and 2.8mm thick.An even more compact format, Memory Stick Duo, is 32mm long, 20mmwide, and 1.6mm thick.The theoretical transfer speed of Memory Stick is 160Mbps.

What is Compact Flash?

A Compact Flash card is an IC (Integrated Circuit) which is stored in acompact and rugged plastic enclosure. Compact Flash cards are designed tostore data and to enable the transfer of data between devices equipped withCompact Flash slots.Current Compact Flash capacities range up to 4GB.

Compact Flash Type I cards are 43mm long, 36mm wide, and 3.3mm thick.Compact Flash Type II cards are 43mm long, 36mm wide, and 5mm thick.The theoretical transfer speed of Compact Flash 2.0 is 16MB/sec.The Compact Flash standard was introduced by SanDisk Corporation in1994.

Compact Flash Plus (CF+)

Compact Flash Plus (CF+) extends Compact Flash to provide functionalitysuch as micro hard drives, modems, Ethernet cards, 802.11 Wi-Fi cards,serial cards, Bluetooth cards, and more.This makes Compact Flash the most versatile of the flash media formats.

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What is a SD Card?

A SD Card (Secure Digital Card) is an IC (Integrated Circuit) which is storedin a compact and rugged plastic enclosure. SD Cards are designed to store

data and to enable the transfer of data between devices equipped with SDCard slots.Current SD Card capacities range up to 1GB.A SD Card is 32mm long, 24mm wide, and 2.1mm thick.An even more compact format, the miniSD Card, is 20mm long, 21.5mmwide, and 1.4mm thick.The theoretical transfer speed of a SD 1.0 Card is 12.5MB/s. SD 1.1 isexpected to raise this to 50MB/s.The SD Card standard was introduced by Toshiba, Matsushita Electric, andSanDisk in 1999.

SDIO

SDIO extends the SD Card standard to include 802.11b WiFi cards,Bluetooth cards, modems, GPS receivers, TV tuners, cameras, digitalrecorders, scanners, fingerprint scanners and more.

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What is a MultiMediaCard (MMC)?

A MultiMediaCard (MMC) is an IC (Integrated Circuit) which is stored in acompact and rugged plastic enclosure. MultiMediaCard (MMC)s are designedto store data and to enable the transfer of data between devices equippedwith MultiMediaCard (MMC) slots.

The MultiMediaCard (MMC) standard was introduced in November of 1997by SanDisk and Siemens AG/Infeneon Technologies AG.Current MultiMediaCard (MMC) capacities range up to 2GB.A MultiMediaCard (MMC) is 32mm long, 24mm wide, and 1.4mm thick.MultiMediaCards can be used in SD Card readers and writers.The theoretical transfer speed of a MultiMediaCard is 2.5MB/s.

What is HD-DVD?

HD-DVD is an optical sotrage format developed by Toshiba and Hitachi.HD-DVD uses a 405nm wavelength blue-violet laser and an 0.65nm pickupaperture. HD-DVD's are coated with a 0.6mm protective surface layer,which is the same thickness used in DVD's.Single-layer HD-DVD disks currently store 15GB of data, which dual-layerHD-DVD disks are able to store 30GB of data.The HD-DVD standard supports the following codec's: MPEG-2, MicrosoftVideo Codec 1, H.264 / MPEG-4 AVC.For security, HD-DVD supports mandatory HDCP encrypted output, volumeidentifiers and Advanced Access Content System (AACS).

What is Blu-Ray?

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Blu-Ray is an optical storage format developed by Sony and Phillips. Blu-Raywas created to store large amounts ofhigh definition video and sound. Blu-ray gets its name from the type of laser it uses to read and write data fromand to the disc, the color of the laser is a hue of blue-violet. Due to theextreme density of these optical discs the data needs to be smaller to fitonto the disc, a blue-violet laser has a shorter wavelength than the normalred lasers used today.How does Blu-ray stack up against other types of discs? Well a normal CDholds about 700 to 800 megabytes of data. A standard DVD holds about 4.7gigabytes. You can also purchase dual layer DVD's that holds about 9.4 totalgigabytes of data. A HD DVD, which is a new DVD technology that also usesblue lasers, holds about 25 gigabytes of data and there are reports that testmedia can hold up to 200 gigabytes of data. The Blu-ray DVD can usuallyhold about 50 gigabytes of data and there are also claims that test mediacan hold up to 200 gigabytes of data.There is currently a market war taking place against both HD DVD's andBlu-ray DVD's. These two types of DVD's are fighting to see who will be the

new form of media for the years to come. As of yet, neither media type hasmade enough inroads to garner a champion.Obviously the major benefit of Blu-ray DVD's is that it is able to hold moredata on one disc, therefore allowing high definition audio and video. Themore data you have, the more data can be read to give a clearer picturewith more color and vividness.One of the benefits of Blu-ray technology is that because data is so closetogether, early types of Blu-ray discs would be contaminated by slightscratches. However, a new coating has been developed that makes Blu-raydiscs extremely difficult to scratch.Blu-ray is looking to make inroads into the consumer electronics market

with the Blu-ray DVD player with its Sony PlayStation. The Sony PlayStationwill include a basic Blu-ray DVD player which might spur sales of media andmake it the de facto standard.The disadvantages to Blu-ray discs are that they are quite expensive. Forinstance, players are selling at about the $1,000 mark and DVD discs will bemore expensive than their standard DVD counterparts. Anotherdisadvantage is that since there are two standards, both Blu-ray and HD,most people are sitting on the sidelines to see who the winner is. BecauseBlu-ray has been developed in part with Sony, Sony has included DRM ordigital rights management that will make it more difficult for people to placeshift and time shift their content.

Blu-Ray Technology

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Blu-Ray uses a 405nm wavelength blue-violet laser and an 0.85nm pickupaperture. Blu-Ray disks are coated with a 0.1mm protective surface layer.Single-layer Blu-Ray disks currently store 23.3GB of data, which dual-layerBlu-Ray disks are able to store 46.6GB of data.The Blu-Ray standard supports the following codec's: MPEG-2, MicrosoftVideo Codec 1, H.264 / MPEG-4 AVC.For security, Blu-Ray supports mandatory HDCP encrypted output, ROM-Mark watermarking, BD+ dynamic cryptology, and the Advanced AccessContent System (AACS).

What is HVD?

HVD (Holographic Versatile Disc) is the next generation in optical disktechnology. HVD is still in a research phase that would phenomenallyincrease the disk storage capacities over the currently existing HD DVD and

Blu-Ray optical disk systems. According to published statistics, whenproduced in full scale, HVDs will have a storage capacity of 3.9 terabytes(39,000 GB) and a data transfer rate of 1 GB/s, which is at least six timesmore than the speed of DVD players. This would, without a doubt, become agiant step in revolutionizing the disk storage industry.Some industry experts call HVDs a next-next generation technology. Thisinference is a direct reference to the enormous storage capacity HVDs offercompared to HD DVD and Blu-Ray optical disk systems, both of which areyet to replace DVDs for mass optical storage. HD DVD and Blu-Ray opticaldisk systems offer a storage capacity of 75 and 90 GB respectively, butneither comes anywhere near the massive storage capacity of HVD.

HVD Technology

HVD uses a technology called 'collinear holography,' in which two laser rays,one blue-green and one red, are collimated into a single beam. The role ofthe blue-green laser is to read the data encoded in the form of laserinterference fringes from the holographic layer on the top, while the redlaser serves the purpose of a reference beam and also to read the servo infofrom the aluminum layer - like in normal CDs - near the bottom of the disk.The servo info is meant to monitor the coordinates of the read head abovethe disk (this is similar to the track, head and sector information on anormal hard disk drive).

How do the laser beams selectively pass through the layers? A layer ofdichroic mirrors that exists between the holographic and servo data layerreflects back the blue-green laser beam, letting only the red laser passthrough it to reach the servo information. By doing so, it actually eliminatesthe possible chances of the interference that can happen due to therefraction of blue-green laser off the servo data pits, a problem that hadaffected the efficiency of many holographic storage media in the past.

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Optical Storage

Most optical storage devices, such as a standard CD (Compact Disc), saveone bit per pulse. HVDs manage to store 60,000 bits per pulse in the sameplace, in a truncated cone shape, that has a diameter of 500 micrometers at

the top and 200 micrometers at the bottom. The HVD Alliance is trying toimprove the storage capacity further to touch its dream 3.9 TB mark byinserting a larger number of cones on each track.

Competing Technologies

In addition to HDV, other proprietary standards are making advances opticaldisk technology. Other players exist, such as those made by Hitachi MaxellLtd and InPhase Technologies. Tapestry Media - a holographic formatpatented by InPhase Technologies - having a storage capacity of 1.6TB anda data transfer rate of 120 MB/s is one such device, while similar a 300 GBdisks with a data transfer rate of 20 Mbit/s is in the pipeline for HitachiMaxell Ltd.

HVD Capacity

The entire US Library of Congress can be stored on six HVDs,assuming that every book has been scanned in the text format. TheLibrary of Congress is the largest in the world and contains over 130million items. The pictures of every landmass on Earth - like the ones shownin Google Earth - can be stored on two HVDs. With MPEG4 ASP encoding, a 3.9 TB HVD can hold anywhere

between 4,600-11,900 hours of video, which is enough for non-stopplaying for a year.

HVD Adoption

The biggest challenge for HVD will be in establishing itself in the commercialmarket, which as of now seems to be a distant dream, given its higher costmargins. It is anticipated that a single HVD, when commercially available,may cost anywhere between $100-120 (by 2006 year's end), and the readerwill be priced anywhere in the range of $10,000 to $15,000. However, likeanything else associated with technology, the price will soon fall as R&DD

costs are recouped and competitions lowers profit margins.

How do I Install a Hard Drive?

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If you would like to replace your old hard drive with an upgraded drive, thisis a simple process that can be done at home. Most new hard drives willcome with installation instructions to make the task easier for you.

Steps To install A Hard Drive

Shut down the computer, and unplug all accessories attached toit. Continue by unplugging the computer completely from its powersource, wait fifteen seconds, and "ground" yourself to preventelectrical shock. Remove the screws holding the computer's cover in place. Remove the computers cover and place it gently to the side. Locate the computer's old hard drive in the drive bay, andremove any cables or wires attached to it. The main cables will be adata cable and a power cable. While removing them, be sure todocument where they attach in order to reattach them. Locate the screws used to anchor the hard drive to the frame ofthe computer case. After the old hard drive has been unscrewed, remove it from theframe, and screw the new hard drive into place. If another hard drive is present, set your jumpers bydetermining which drive is the "master" and "slave" for an older drive.The setting can remain as "single" or "master" when one drive isinstalled. Reattach the data cable and power cable which were attached tothe originalhard drive. Replace the computers cover.

Plug all cables back into the computer. Power on the computer. If it is installed correctly, the computer should auto-recognizethe new hard drive.

What is a hard disk partition?

A hard disk partition is a defined storage space on a hard drive.Most operating systems allow users to divide a hard disk into multiplepartitions, in effect maaking one physical hard disk into several smallerlogical hard disks.

Reasons to Use Hard Disk Partitions

A user may decide to split a hard disk into multiple partitions in order toorganize his data more effectively. On Microsoft Windows machines, it iscommon to store the OS and applications on one hard disk partition anduser data on another hard disk partition. When a problem occurs with

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Microsoft Windows, the OS partition can be completely formatted andreinstalled without affecting the data partition.A user may decide to split a hard disk into multiple partitions becausesmaller partitions often have smaller cluster sizes. A cluster size is thesmallest chunk of data which a partition can store. A large partition mighthave a cluster size of 16KB. This mens that a file with one character in it willoccupy 16KB of space on the disk. In a smaller partition, that file might onlyrequire 4KB to store. This is a useful strategy if you are storing a largenumber of small files.A user may have to split a large hard disk into multiple partitions if the harddisk is larger than the partition size supported by the operating system.

Creating Hard Disk Partitions

Most operating system use the `fdisk` command to create hard diskpartitions. Many ooperating systems also have graphical tools whichaccomplish the same task.

Hard Disk Partitions and File Systems

You don't actually store data in hard disk partitions.You store file systems in hard disk partitions and then you store data inthese file systems.Some operating systems blur the lines between partitions and filesystems.

The Partition Table

Partition information is stored in the partition table, a reserved area at the

beginning of a hard disk.

Extended Partitions

A standard partition table is only able to store information about fourpartitions. At one time this meant that a hard disk could have a maximum offour partitions.To work around this limitation, extended partitions were created.An extended partition stores information about other partitions. By using anextended partition, you can create many more than four partitions on yourhard disk.

The four standard partitions are often called the primary partitions.Partitions configured into an extended partition are often referred to aslogical partitions.

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Partition Types

When a partition is created, a special byte of data is written to record whattype of partition it is.Because one hard disk may be shared by multiple operating systems,

operating systems tendto agree on the meaning of these values.The table below lists some of the partition types in use.

Partition Number Partition Type

00 Empty

01 DOS 12-bit FAT

02 XENIX root

03 XENIX usr

04 DOS 16-bit FAT =3207 OS/2 HPFS, WinNT NTFS

08 AIX

09 AIX bootable

0a OS/2 Boot Manager

0b Win95 FAT32

0c Win95 FAT32 (LBA)

0e Win95 FAT16 (LBA)

0f Win95 Extended (LBA)

35 OS/2 JFS39 Plan 9

40 Venix 80286

51 Novell

52 Microport

63 Unix System V, Mach, GNU HURD

64 Novell Netware 286

65 Novell Netware 386

75 PIC/IX

80 MINIX until 1.4a

81 MINUX, Linux

82 Solaris X86, Linux swap

83 Linux native

85 Linux extended

93 Amoeba

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94 Amoeba BBT

a5 FreeBSD, NetBSD, BSD/386, 386BSD

a6 OpenBSD

a7 NEXTSTEP

b7 BSDI BSD/386 filesystemb8 BSDI BSD/386 swap

be Solaris 8 bootable

bf Solaris x86

c7 Syrinx

db CP/M

e1 DOS access

e3 DOS R/O

eb BeOS BFS

fb VMWare filesystem

fc VMWare swap

f2 DOS secondary

ff Xenix Bad Block Table

What is free partition software?

A wide range of free partition software is available. Be very careful whenusing any software application which writes to the partition table, the MBR(Master Boot Record), or the boot sector.Always backup your hard drive completely before using any free partitionsoftware. If you lose data, you have no one to blame but yourself.

Free Partition Software

Partition Saving

Partition Saving is an MS-DOS based partition backup and recoveryprogram. Partition Saving can copy a partition to a file.Partition Saving is intelligent enough to copy only occupied sectors to thefile, if the partition is FAT12, FAT16, FAT32, NTFS or ext2.Partition Saving is also able to compress data in the partition and split it into

several files. This is especially useful when saving hard drive partitions toCD's or DVD's.

Partition Image

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Partition Image is a Linux/Unix utility which saves partitions to an imagefile. The image file can be compressed to save disk space, and split intomultiple files to be copied on removable media.Partition Image will only copy data from the used portions of the partition.For speed and efficiency, free blocks are not written to the image file.Partition Image supports ext2fs/ext3fs, ReiserFS, FAT16/32, HPFS, JFS andXFS.

SystemRescueCd

SystemRescueCd is a Linux system on a bootable CD-ROM for repairing yoursystem and your data after a crash.SystemRescueCd also aims to provide an easy way to carry outadministrative tasks on your computer, such as creating and editing thepartitions of the hard disk.SystemRescueCd contains a lot of system utilities (parted, partimage,fstools, ...) and basic ones (editors, midnight commander, network tools). Itaims to be very easy to use: just boot from the CD-ROM, and you can do

everything.The kernel of the system supports ext2/ext3, ReiserFS, XFS, JFS, VFAT,NTFS, ISO9660, Samba and NFS.

Ranish Partition Manager

Ranish Partition Manager is a powerful hard disk partitioning tool. It givesusers high level of control for running multiple operating systems, such asFreeBSD, Linux, Windows 98/XP, and FreeDOS on a single disk.Partition Manager can create, copy, and resize primary and extendedpartitions. It includes a command line interface and a simulation mode thatworks with large files so that you can safely experiment before working onthe real hard drive partition tables.

eXtended FDisk

eXtended FDisk, or short XFDisk, is a free DOS FDISK replacement thatoffers more comfort and comes with a boot manager that allows you to havemore than one operating system installed on your hard disk.With XFDisk you can partition your hard disk or install and configure theboot manager, which will be located in the first 17 sectors of your first harddisk. The boot manager will not occupy a partition, so you can fully use thefour available primary partitions per hard disk. If you choose to have anextended partition with logical drives on your hard disk, XFDisktransparently manages the extended partition for you.XFDisk and the boot manager support more than one hard disk and evenbooting from logical drives.

TestDisk

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TestDisk is a tool to check and undelete partitions.TestDisk works with the following partition types:

BeFS ( BeOS ) BSD disklabel ( FreeBSD/OpenBSD/NetBSD ) CramFS (Compressed File System) DOS/Windows FAT12, FAT16 and FAT32 HFS, Hierarchical File System JFS, IBM's Journaled File System Linux Ext2 and Ext3 Linux Raid Linux Swap (versions 1 and 2) LVM and LVM2, Linux Logical Volume Manager Netware NSS NTFS ( Windows NT/2K/XP/2003 ) ReiserFS 3.5 and 3.6 UFS (Sun/BSD/...) XFS, SGI's Journaled File System

TestDisk runs under DOS/Win9x, Windows NT 4/2000/XP/2003, Linux ,FreeBSD, NetBSD, OpenBSD, and Sun Solaris.

GNU Parted

GNU Parted is a program for creating, destroying, resizing, checking andcopying partitions, and the file systems on them. This is useful for creatingspace for new operating systems, reorganizing disk usage, copying databetween hard drives and drive imaging.GNU Parted supports operations on ext2, ext3, FAT16, FAT32, Linux Swap,HFS and HFS+, JFS, NTFS, ReiserFS, UFS, and XFS. All operations are notsupported across all file systems.

The Partition Resizer

Partition Resizer is a small DOS executable which can re-arrange yourpartitions safely, quickly and fuss-free.

Free FDISK

Free FDISK is the replacement FDISK which is available in FreeDOS.Free FDISK features include:

Supports hard disks up to 128GB in size.

Has the "standard" fdisk user interface. Command-line support is compatible with Microsoft'sundocumented FDISK commands. Has extended command-line support to give you completecontrol over hard disk configuration from batch files. Is designed for both occasional use as well as large scaleautomated operating system roll-outs and cloning projects.. Comes with BootEasy, a compact multi-boot loader. Can be customized with an easy to use configuration file.

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Allows the use of boot loaders from other operating systems. Free FDISK is Open Source and licensed under the GNU GPL.

MBRWork

MBRWork is a utility to perform some common and uncommon tasks to theMBR/EMBR/Sectors of a hard drive.MBRWork is a tool for power users who understand how computers work.

What is a bad sector?

What is a Sector?

A sector is a small area on the surface of a hard drive or a floppy disk.Hard drives usually have several platters. The platters are the discs whichare covered with magnetic material which is used to hold data. Floppy disk

drives contain only one platter.Platters are divided into a set of concentric rings called tracks. A 1.44MBfloppy disk has 160 tracks. Hard drives have thousands of tracks.Each of these tracks is divided into smaller storage areas called sectors. Asector is the smallest storage area on a disk.

What is a Bad Sector?

Hard drives are contain millions of sectors. It is very normal for some ofthese sectors to be bad sectors, even when the drive is first manufactured.In addition, a small number of sectors will normally go bad during thelifespan of a drive.When this happens, the data in those sectors may be lost, but the data onthe rest of the disk will be unaffected and the disk is still completely usable.A bad sector cannot be repaired, but it can be marked as unusable. Oncemarked as unusable, the Operating System will know not to attempt to storedata in that bad sector. The storage capacity of the disk will be decreasedby the amount ofstorage space in the bad sector.If your hard drive develops a bad sector, back the hard drive upimmediately. If the bad sector was caused by a faulty drive head, theproblem can quickly spread to other sectors on the disk.

How do I repair a bad sector?

Occasionally one or more sectors on an otherwise good hard drive will gobad.When this happens, the data in those sectors may be lost, but the data onthe rest of the disk will be unaffected and the disk is still completely usable.Those bad sectors can not be repaired, but they can be marked as unusable.Once marked as unusable, the Operating System will know not to attempt to

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store data in those bad sectors. The total disk capacity will be decreased bythe amount of storage space in those bad sectors.If your hard drive is experiencing a bad sector, back it up immediately. Ifthe bad sector was caused by a faulty drive head, the problem can spread tomany other sectors across the disk.

How to "Repair" a Bad Sector in Windows XP

Press the button. Select . Under Hard Disk Drives highlight the disk which you want toscan. Open the menu and choose Open the tab. Click the button.

In earlier version of Microsoft Windows and DOS, this functionality was built

into the `scandisk` and `chkdsk` utilities.Once the bad sector or sectors have been "repaired", continue to back upyour hard drive on a regular basis. Hard drives are mechanical devices andall mechanical devices will eventuallyfail.

Where is Scan Disk in Win XP?

Scan Disk has been removed from Windows 2000 and Win XP. Thefunctionality previously found in Scan Disk has been built into Explorer.

How to Scan Disk in Win XP

Press the button. Select . Under Hard Disk Drives highlight the disk which you want toscan. Open the menu and choose Open the tab. Click the button

How does hard drive recovery work?

Hard drives, like all mechanical devices, eventually break down.Common hard drive problems include:

User errors Software errors Hard drive electronics failures Hard drive arm failures

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Hard drive platter failures

User Errors

User errors include accidentally deleting or overwriting files and accidentally

formatting a or deleting a partition.User errors can sometimes be resolved through the use of off-the-shelf datarecovery software.

Software Errors

Software errors usually result from software writing data to the wrong partof the disk.Errors cause by software are generally much more difficult for off-the-shelfdata recovery software to correct. This task may require the services of adata recovery specialist.

Hard Drive Electronics Failures

When a hard drive physically fails, sometimes the mechanical parts of thehard drive remain undamaged. This can happen, for example, if the harddrive is subject to a power surge or a discharge of static electricity.In these cases, it is usually possible to take the mechanical parts out of thehard drive assembly and place them into another identical hard drive unit.This should be done in a clean-room environment, to prevent dust fromdamaging the hard drive.

Hard Drive Arm Failures

Hard drive arm failures are very common. When the hard drive arm fails,there is a very good chance that it will damage the hard drive platters.When you hear the clicking noises from your hard drive which signal a harddrive arm failure, back up all necessary data immediately and power thesystem down as soon as possible.If the hard drive platters have not been damaged, a data recovery specialistmay still be able to recover data from a hard drive with a damaged harddrive arm.

Hard Drive Platter Failures

No drive platter is manufactured perfectly. There will always be some badspots on the platter surface. Modern hard drives automatically mark thosebad spots as unusable and do not store data there.Sometimes bad spots will develop during the life of the hard drive. The harddrive will mark that spot bad and attempt to move the data to a good spoton the hard drive. This may, or may not, result in the loss of some data.

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Serious hard drive platter failures can occur as a result of hard drive armfailures. In these cases, the hard drive platters are being scratched. Yourdata is being scratched right off the surface of the platters! You can oftenhear this damage occuring. These failures are very expensive or impossibleto recover.

The Solution to Hard Drive Recovery: Backup

The best method of hard drive recovery is to throw away the failed harddrive and restore your data from backup to a brand new drive.Backing up your data is a critically important preventative maintenancetask. Don't put yourself at risk by not properly backing up your data.

What is free data recovery software?

Never install free data recovery software on the drive that you are

attempting to recover data from.Always install and run free data recovery software from a separate drive,such as an external hard disk or flash drive.

Free Data Recovery Software

PC Inspector File Recovery

PC Inspector File Recovery is a data recovery program that supports the FAT12/16/32 and NTFS file systems.

Finds partitions automatically, even if the boot sector or FAT hasbeen erased or damaged Recovers files with the original time and date stamp Supports the saving of recovered files on network drives Recovers file contents, even when the file header is no longeravailable.

PC Inspector Smart Recovery

PC Inspector Smart Recovery is a data recovery program for Flash Card,Smart Media, Sony Memory Stick, IBM Micro Drive, Multimedia Card, SecureDigital Card or any other data carrier for digital cameras.If you have unintentionally deleted or formatted pictures, videos or soundfiles on your data carrier or have pulled it out during a write operation, no

matter - PC Inspector Smart Recovery can easily, quickly and absolutelyreliably reconstruct the lost data.PC Inspector Smart Recovery runs on Windows 95/98, ME, NT 4.0, XP andWindows 2000 systems.

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there is a good chance the data can be recovered by using a variety of harddrive data recovering techniques.

Reasons for Hard Drive Crashes

Hard drive crashes occur for a variety of reasons. One of the main causesfor a full blown hard drive crash is generally attributed to a hardware issues.The hard drive is a magnetic disc which spins and has an extended arm thatcollected data from any area of the hard drive. If the arm fails to function orthe motor overheats or stops spinning, then there is a chance your harddrive will crash rendering data seemingly inaccessible from all hard driveareas. Hard drive crashes can also be caused by corrupted registry files orsystem files. Viruses, Spyware, adware, and Trojan horses can also causesystem file corruption resulting in a hard drive crash.

Determining the Actual Cause of a Hard Drive Crash

To determine whether your hard drive has crashed due to mechanical failureor a software related problem is relatively simple. Check whether theflashing light in front of your computer case is blinking or not. If the light isflashing but the computer is not booting up, then the problem may besoftware related; and in most cases the cause is either virus related or dueto a corrupted system file. These types of hard drive crashes can generallybe recovered by reinstalling the operating system.If the flashing light in the front of the computer case is not blinking, itindicates that there is no hard drive activity and is generally attributed to amechanical problem. In this scenario a qualified computer technician may beneeded to fix problematic hard drive issues.

Physical Damage

Most physical damage to a hard drive, such as failed motors or headcrashes, cannot be repaired by typical computer users. Physical damage of ahard drive often results in some data loss and in most cases you may not beable to recover all the lost data. However, the physical damage can alsoresult in the damage of the logical structures of the file system whichprevents file system structures from being completely written to the harddrive.If the hard drive has any physical damage, you need to seek a technical

expert to assist in recovery or choose a data recovery company to recoveras much data as possible. Most hard drive data recovery firms utilize thelatest tools like magnetometers to retrieve the lost bits from the magneticmedia. The recovered raw bits from the damaged hard drive are used toconstruct a new disk image, and the logical damage can be repaired.

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The Role of Hard Drive Data Recovery Software Programs

Hard drive data recovery software programs play a major role in recoveringhard drive data. You will find several companies that offer these types ofprograms. Most will automatically create backup copies of all your files and

folders reducing the worry of potential data loss. A good hard drive datarecovery program can recover all the important files or folders which vanishafter partition loss, accidental format, file or directory deletion, softwaremalfunction or even a virus attack. Whether you accidentally delete the filesor your computer crashes, data recovery software can locate the lost filesand recover them from your hard drive.The main contexts where hard drive data recovery software is found usefulinclude:

1. Missing file or directory2. Formatted hard drive3. Deleted file or directory

4. Unbootable hard drive5. Inaccessible hard drive6. Recovery of deleted files and folders on FAT and NTFS harddrive or partitions7. Data recovery on damaged FAT and NTFS partitions8. Damaged or corrupted partition table

The majority of hard drive data recovery software programs currentlyavailable is easy to install, user friendly, and is virtually self maintaining.However, it's a good idea to purchase these programs from a trustedsoftware supplier.

Most software companies understand the consumer's need to be assured ofvalue and ease of use, so if the data recovery software you selected has atrail offer, it may be a good idea to give it a test drive before you make apurchase.

What is a full backup?

A full backup is a backup of every file on a file system, whether that file haschanged or not.The alternatives to a full backup are incremental backup and differentialbackup.

A full backup takes longer to accomplish and requires the most storagespace on the backup media, but it also provides the quickest restore times.A full backup should be performed weekly or monthly on productionsystems, along with daily differential backups.A full backup should also be performed before any major planned changesto a system.

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What is an incremental backup?

A incremental backup is a backup of every file on a filesystem which haschanged since the last backup.The alternatives to an incremental backup are differential backup and full

backup.An incremental backup is the fastest backup and requires the least storagespace on the backup media. However, incremental backups also require thelongest time and the most tapes to restore.Incremental backups should be used only in environments where backuptime or backup storage media are extremely constrained. For mostenvironments, a weekly full backup and a daily differential backip representa better plan.If you perform a full backup on Sunday along with incremental backupsevery night and the system crashes on Thursday, you will need to restorethe full backup from Sunday along with the incremental backups fromMonday, Tuesday, and Wednesday.In contrast, if you perform a full backup on Sunday and a differential everynight, when the system crashes on Thursday you will only need to restorethe full backup from Sunday and the differential backup from Wednesday.

What is a differential backup?

A differential backup is a backup of every file on a file system which haschanged since the last full backup.The alternatives to a differential backup are incremental backup and fullbackup.A differential backup can be an optimal middle-ground between a fullbackup and an incremental backup.A differential backup is not as fast as an incremental backup, but it is fasterthan a full backup. A differential backup requires more storage space thanan incremental backup, but less than a full backup.A differential backup requires more time to restore than a full backup, butnot as much time to restore as an incremental backup.If you perform a full backup on Sunday and a differential every night, andthe system crashes on Thursday, you will only need to restore the fullbackup from Sunday and the differential backup from Wednesday.In contrast, if you perform a full backup on Sunday and incremental backupsevery night, when the system crashes on Thursday, you will need to restore

the full backup from Sunday along with the incremental backups fromMonday, Tuesday, and Wednesday.A differential backup should be performed daily on production systems.

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What is network backup?

Network backup is any backup system where the data to be backed uptraverses the network to reach the backup media.Network backup typically requires a client-server software architecture. The

backup server resides on a centralized server and the backup clients resideon every system to be backed up.Advanced network backup systems can manage backup media which arealso connected to the backup server via a network.Network backup systems are much more scalable and manageable thanlocal backup systems where tape drives are attached to each comouterystem.Because network backup systems can backup so many computers, theynormally utilize tape autochangers to give them greater storage capacity.

Network Backup Software

Free network backup software includes Amanda, Bacula, and BackupPC.Commercial network backup software includes HP OpenView Storage DataProtector, Veritas NetBackup, and EMC Legato Networker.

What are common computer backup methods?

It is a well-known fact that most computers are susceptible to hard drivecrashes or virus attacks. Backing up information is a practical and necessaryprecaution to protect one's data from being lost forever.

There are several realistic methods for backing up data. The best backupmethod for your data depends opon many factors, including: the importanceof the data, the amount of data to be backed up, and the funds available forbackup. Here are some of the most commonly used data backup solutions.

Flash Memory

Flash memory, also known as memory sticks, flash drives, or thumb drives,are a suitable solution for data backup when the backup amount issomewhat small. Flash memory drives are easy to plug into any PC with aUSB port. These drives offer unlimited rewrite capabilities and are availablein capacities ranging anywhere from 64 MB to 4 GB. Flash memory datadurability is estimated to be roughly 10 years. Another advantage of flashmemory is that data stored on flash drives is not susceptible to damagecaused by magnets.

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DVD Backup

DVD backup is a practical alternative for home users and small businesses.DVD technologies include DVD-RW, DVD+RW, DVD-R, DVD+R, DVD-RAM,

as well as dual layer DVD technologies. Single-layer DVDs can hold up to 4.7GB of data and dual-layer DVDs can hold up to 8.5 GB. DVD technology is asuitable option for storing backup data medium amounts of backup data.

Hard Drives

As the prices of hard drives are dropping each year, individuals andbusinesses are turning to hard drives as a backup option. Copying andretrieving data from separate hard drives is very easy. The primarydisadvantages are cost and the worry that a malware attack which affectsthe primary hard drives could also effect the backup hard drives.

Tape Backup

Combined with their decreased accessibility and the advances made in theavailability of such storage devices as the CD-R, the CD-RW, and the DVD-R, tape backups have become less popular and practically obsolete for homecomputer users. However, tape backup is still the primary backup methodused in business environments. Tape backups are available in numerous

capacities such as 4mm helical for low-end systems, 8mm helical scantechnology for mid-range systems, and AIT, DLT and LTO for high-endsystems. Compared to several other media solutions, tape drives typicallyprovide the highest storage capacities at the lowest cost. One drawback tokeep in mind, however, is the write speed of these drives, which iscomparatively low.

Online Storage

Online storage is one of the newest methods of storing your files, of coursebackup data also. Onlien storage solutions enable people to upload theirdata to a reliable server located in a secure environment. Anotheradvantage of storing files online is that users can access these files from anylocation as long as they have a computer with Internet access.

What is DLT?

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DLT (Digital Linear Tape) is a magnetic tape format developed by DEC (nowHewlett-Packard).DLT tapes are 1/2 inch wide and are packaged in study plastic containers.DLT tapes store between 10GB and 40GB of uncompressed data.A SuperDLT II tape can store up to 300GB of uncompressed data and cantransfer as much as 36MB per second.

DLT Alternatives

Alternative tape storage standards to DLT include LTO and AIT.

What is LTO tape?

LTO (Linear Tape-Open) is a tape standard developed by HP, IBM, andSeagate as a competitor to DLT.

LTO tape stores data in 384 data tracks which are divided into four databands of 96 tracks each.The four data bands are bordered by bands of servo information which arewritten during tape manufacture.Data bands are filled one-at-a-time, in a linearfashion.LTO tapes contain 4KB of non-volatile memory which can be read through anon-contacting passive RF interface. This storage space contains data aboutthe tape and can be read without the time required to read the magnetictape itself.

LTO Tape Generations

The LTO tape standard is designed to last for four generations of magnetictape technology.

LTO Tape Generation Uncompressed Capacity

Generation 1 100GB

Generation 2 200GB

Generation 3 400GB

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Generation 4 800GB

LTO Tape Physical Specifications

An LTO tape is approximately 4.1" x 4.0" x 0.8".

LTO Alternatives

Alternative tape storage standards to LTO include DLT and AIT.

Find a Great Deal on LTO Equipment on eBay

What is AIT?

AIT (Advanced Intelligent Tape) is a magnetic tape format developed bySony.AIT tapes contain non-volatile memory called Memory-in-Cassette (MIC).This storage space contains data about the tape which can be read quickly

by a tape drive, without having to read data from the slower magneticmedia.

AIT Magnetic Media

AIT uses Advanced Metal Evaporated (AME) tape. To create AME tape,cobalt is vaporized and deposited directly on the base film.AME technology gives AIT tape both high-capacity and exceptionaldurability. An AIT tape should support 30,000 media uses with an MTBF of400,000 hours.

AIT Tape Capacities

AIT Tape Specification Storage Capacity

SDX125C 25GB

SDX135C 35GB

TAITE-20N 20GB

TAIT1-40N/40C 40GB

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SDX236C 36GB

SDX2-50C 50GB

SDX2-50W 50GB

SDX3-100C 100GB

SDX3-100W 100GBSDX4-200C 200GB

SDX4-200W 200GB

AIT Physical Specifications

AIT tapes are 95mm x 62.5mm x 15.0mm. This compact format is veryconvenient for use in 3.5" drive bays.

AIT Alternatives

Alternative tape storage standards to AIT include DLT and LTO.

What is Online Data Storage?

Online data storage, also known as Internet data storage, is a technologywhich allows people to store their data in the Internet. With broadbandspeeds becoming faster and bandwidth pricing dropping every year, morepeople are interested in purchasing online data storage. Online data storagenot only provides an additional flexible source for storing data but also actsas a backup mechanism and provides an effective method of sharing datawith others.This is the reason why Internet data storage is increasingly popular even asthe costs of physical local storage devices - such as hard drives, CD-R, and

tape backups - are coming down by the day. Another advantage of onlinedata storage is that it is easy to expand. Whenever you reach the maximumcapacity limit, you can simply purchase additional space for storage. Thereis no need for you to purchase and install additional storage hardware.With online data storage, the user can access data from any location with acomputer and Internet connection. This s convenient for businesses andhome computer users alike. Businesses that use online data storage canpassword protect access to business files, while home computer users can

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use it for something as simple as sharing photos, music, or videos with theirfamily members.Another noted advantage of online data storage is data backup. Computersare susceptible to hard drive crashes or virus attacks. Hence taking databackups frequently would be a safe way to protect your data from gettinglost forever. However, it should be kept in mind that backup data must bestored in some other place other than the same computer or the samephysical location. To do so, there is no better an option than online datastorage.There are several types of online data storage. If the user is looking forstorage space for some non-sensitive data, then the basic online storage isan ideal one. On the other hand, for sensitive data, additional security maybe required - such as data encryption or two-factor authentication. In suchcases, online vendors typically use strong encryption technologies to keepuser's data safe and secure during transmission over the Internet.Nowadays there are several vendors offering online data storage facilities.Users typically pay fees based upon the amount of space they need.

Generally online data storage vendors feature a fully managed and securesolution with 24x7 technical support and monitoring. Further almost allInternet data storage services are secure and password protected. Somevendors provide an additional measure of security by providing users with apassword token, which automatically generates passwords using two factorauthentication.

What is Fibre Channel?

Fibre Channel is a set of standards for connecting storage devices in a fabricnetwork.

Fibre Channel supports data transmission rates of 100MBps. Fibre Channelsupports the connection of 126 devices on a single network.

Fibre Channel Topologies

Fibre Channel supports three fabric topologies:

Fabric Loop Point-to-Point

Fiber Channel Physical Connectivity

Fiber Channel supports connectivity over fiber optic cabling or copper wiring.Fibre Channel devices using fiber optic cabling use two unidirectional fiberoptic cables for each connection. One fiber optic cable is used fortransmitting, the other for receiving. Fibre channel over fiber optic cablesupports cable distances of up to 10Km.

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Fibre Channel devices which communicate over copper cabling are limited todistances of 30m.

Fibre Channel Devices

Fibre Channel Devices include:

Host Bust Adapters (HBA's) Fibre Channel Hubs Fibre Channel Switches

Fibre Channel Ports

Fibre Channel uses a shorthand terminology to describe different types ofconnections to the fibre channel network.Fibre Channel uses the term "ports" and defines seven different types ofports:

Short

Name

Descriptive

Name

Device

TypePort Function

N-port Network Port NodesNode port used to connect a node to aFibre Channel switch

F-port Fabric Port SwitchesSwitch port used to connect the FibreChannel fabric to a node

L-port Loop Port NodesNode port used to connect a node to aFibre Channel loop

NL-portNetwork + LoopPort

NodesNode port which connects to bothloops and switches

FL-portFabric + LoopPort

SwitchesSwitch port which connects to bothloops and switches

E-port Extender Port SwitchesUsed to cascade fibre channel switchestogether

G-port General Port SwitchesGeneral purpose port which can beconfigured to emulate other port types

What is Network Attached Storage?

Network Attached Storage (NAS) is a term used to describe a completestorage system which is designed to be attached to a traditional datanetwork.This differentiates Network Attached Storage devices from SAN's (StorageArea Networks). A SAN is a separate network to which storage devices areattached.

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In most cases, Network Attached Storage is less expensive to purchase andless complex to operate than a Storage Area Network. However, a SAN canprovide better performance and a larger range of configuration options.

Network Attached Storage Protocols

NAS servers commonly support NFS (Network File System) and CIFS(Common Internet File System). They may also support other storageprotocols, such as FTP (File Transfer Protocol) or SCP (Secure CoPy).

Network Atttached Storage Connections

NAS server are typically attached to the network via Ethernet. However,NAS devices are also available which connect to Fibre Channel networks.Wireless 802.11 Network Attached Storage devices are now appearing onthe market.

Network Attached Storage Drives

NAS devices have traditionally utilized SCSI (Small Computer SystemsInterface) internally, but NAS devices can be built using any disktechnology. NAS devices based on ATA disks are now available.In addition to disk storage, NAS devices can also support magnetic tape andoptical media such as CD and DVD.

What is a HBA?

A HBA, or Host Bus Adapter, is the interface card which connects a host to aSAN (Storage Area Network).A HBA could be more accurately referred to as a "Host I/O controller".

What is LUN masking?

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LUN (Logical Unit Number) Masking is an authorization process that makes aLUN available to some hosts and unavailable to other hosts.LUN Masking is implemented primarily at the HBA (Host Bus Adapater) level.LUN Masking implemented at this level is vulnerable to any attack thatcompromises the HBA.Some storage controllers also support LUN Masking.LUN Masking is important because Wi

raid and its associate

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