clariion blogs_ january 2008 lun's

8/3/2019 Clariion Blogs_ January 2008 LUN's

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Clariion Disk Format

Disk Format

The Clariion Formats the disks in Blocks. Each Block written out

to the disk is 520 bytes in size. Of the 520 bytes, 512 bytes is

used to store the actual DATA written to the block. The remaining

8 bytes per block is used by the Clariion to store System

Information, such as a Timestamp, Parity Information, Checksum

Data.

Element Size – The Element Size of a disk is determined when a

LUN is bound to the RAID Group. In previous versions of

Navisphere, a user could configure the Element Size from 4

blocks per disk 256 blocks per disk. Now, the default Element

Size in Navisphere is 128. This means that the Clariion will write

128 blocks of data to one physical disk in the RAID Group before

moving to the next disk in the RAID Group and write another 128

blocks to that disk, so on and so on.

Chunk Size – The Chunk Size is the amount of Data the Clariion

writes to a physical disk at a time. The Chunk Size is calculated

by multiplying the Element Size by the amount of Data per block

written by the Clariion.

128 blocks x 512 bytes of Data per block = 65,536 bytes of Data

per Disk. That is equal to 64 KB. So, the Chunk Size, the amount

of Data the Clariion writes to a single disk, before writing to the

next disk in the RAID Group is 64 KB.Posted by san guy at 11:42 AM 5 comments

LUNs

on blogs: January 2008 http://clariionblogs.blogspot.com/2008_01_01_arc

12/8/2011



LUNs

As stated in the Host Configuration Slide, a LUN is the disk space

that is created on the Clariion. The LUN is the space that is

presented to the host. The host will see the LUN as a “Local Disk.”

In Windows, the Clariion LUN wil l show up in Disk Manager is

Drive #, which the Windows Administrator can now format,

partition, assign a Drive Letter, etc…

In UNIX, the Clariion LUN will show up as a c_t_d_ address,

which the UNIX Administrator can now mount.

A LUN is owned by a single Storage Processor at a time. When

creating a LUN, you assign the LUN to a Storage Processor, SPA,

SPB or let the Clariion choose by selecting AUTO. The Auto option

lets the Clariion assign the next LUN to the Storage Processor

with the fewest number of LUNs.

The Properties/Settings of LUN during creation/binding are:

1. Selecting which RAID Group the LUN will be bound to.

2. If it is the first LUN created on a RAID Group, the first LUN will

set the RAID Type for the entire RAID Group. Therefore, when

creating/binding the first LUN on a RAID Group, you can selectthe RAID Type.

3. Select a LUN Id or number for the LUN.

4. Specify a REBUILD PRIORITY for the LUN in the event of a Hot

Spare replacing a failed disk.

5. Specify a VERIFY PRIORITY for the LUN to determine the speed

in which the Clariion runs a “SNIFFER” in the background to

scrub the disks.

6. Enable or Disable Read and Write Cache at the LUN level. An

example might be to disable Read/Write Cache for a LUN that is

given to a Development Server. This ensures that the

Development LUNs will not use the Cache that is needed for

Production Data.

7. Enable Auto Assign. By default this box is unchecked in

Navisphere. That is because you will have some sort of Host

Based Software that will manage the trespassing and failing back

of a LUN.

8. Number of LUNs to Bind. You can bind up to 128 LUNs on a

single RAID Group.

9. SP Ownership. You can select if you want your LUN(s) to

belong to SP A, SP B, or the AUTO option in which the Clariion

decides LUN ownership based on the Storage Processor with the

fewest number of LUNs.

10. LUN Size. You specify the size of a LUN by entering the

numbers and selectin MB Me aB tes GB Gi aB tes TB


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(TeraBytes), or Block Count to specify the number of blocks a

LUN will be. This is critical for SnapView Clones, and MirrorView

Secondary LUNs.

The amount of LUNs a Clariion can support is going to be Clariion

specific.

CX 300 – 512 LUNs

CX3-20 – 1024 LUNs

CX3-80 – 2048 LUNs

Posted by san guy at 11:33 AM 2 comments

Tuesday, January 29, 2008

RAID 1_0

Order of Disks in RAID Group for RAID 1_0.

When creating a RAID 1_0 Raid Group, it is important to know

and understand the order of the drives as they are put into the

RAID Group will absolutely make a difference in the Performance

and Protection of that RAID Group. If left to the Clariion, it will

simply choose the next disks in the order in which is sees the

disks to create the RAID Group. However, this may not be the

best way to configure a RAID 1_0 RAID Group. Navisphere will

take the next disks available, which are usually right next to one

another in the same enclosure.

In a RAID 1_0 Group, we want the RAID Group to span multipleenclosures as illustrated above. The reason for this is as we can

see, the Data Disks will be on Bus 1_Enclosure 0, and the

Mirrored Data Disks will be on Bus 2_Enclosure 0. The advantage

of creating the RAID Group this way is that we place the Data and

Mirrors on two separate enclosures. In the event of an enclosure

failure, the other enclosure could still be alive and maintaining

access to the data or the mirrored data. The second advantage is

Performance. Performance could be gained through this

configuration because you are spreading the workload of the

application across two different buses on the back of the Clariion.


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_

Group. In order to for the disks to be entered into the RAID

Group in this order, they must be manually entered into the RAID

Group this way via Navisphere or the Command Line.

The first disk into the RAID Group receives Data Block 1.

The second disk into the RAID Group receives the Mirror of Data

Block 1.

The third disk into the RAID Group receives Data Block 2.

The fourth disk into the RAID Group receives the Mirror of DataBlock 2.

The fifth disk into the RAID Group received Data Block 3.

The sixth disk into the RAID Group receives the Mirror of Data

Block 3.

If we let the Clariion choose these disks in its particular order, it

would select them:

First disk – 1_0_0 (Data Block 1)

Second disk – 1_0_1 (Mirror of Data Block 1)

Third disk – 1_0_2 (Data Block 2)

Fourth disk – 2_0_0 (Mirror of Data Block 2)

Fifth disk – 2_0_1 (Data Block 3)

Sixth disk – 2_0_2 (Mirror of Data Block 3)

This defeats the purpose of having the Mirrored Data on a

different enclosure than the Data Disks.

Posted by san guy at 1:49 PM 11 comments

RAID Groups and Types

RAID GROUPS and RAID Types

The above slide illustrates the concept of creating a RAID Group

and the supported RAID types of the Clariions.

RAID Groups

The concept of a RAID Group on a Clariion is to group together a

number of disks on the Clariion into one big group. Let’s say that

we need a 1 TB LUN. The disks we have a 200 GB in size. We


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would have to group together five (5) disks to get to the 1 TB

size needed for the LUN. I know we haven’t taken into account

for parity and what the RAW capacity of a drive is, but that is just

a very basic idea of what we mean by a RAID Group. RAID

Groups also allow you to configure the Clariion in a way so that

you will know what LUNs, Applications, etc…live on what set of

disks in the back of the Clariion. For instance, you wouldn’t want

an Oracle Database LUN on the same RAID Group (Disks) as a

SQL Database running on the same Clariion. This allows you to

create a RAID Group of a # of disks for the Oracle Database, and

another RAID Group of a different set of disks for the SQL

Database.

RAID Types

Above are the supported RAID types of the Clariion.

RAID 0 – Striping Data with NO Data Protection. The

Clariions Cache will write the data out to disk in blocks (chunks)

that we will discuss later. For RAID 0, the Clari ion writes/stripes

the data across all of the disks in the RAID Group. This is

fantastic for performance, but if one of the disks fail in the RAID

0 Group, then the data will be lost because there is no protectionof that data (i.e. mirroring, parity).

RAID 1 – Mirroring. The Clariion will write the Data out to the

first disk in the RAID Group, and write the exact data to another

disk in that RAID 1 Group. This is great in terms of data

protection because if you were to lose the data disk, the mirror

would have the exact copy of the data disk, allowing the user to

access the disk.

RAID 1_0 – Mirroring and Striping Data. This is the best of

both worlds if set up properly. This type of RAID Group will allow

the Clariion to stripe data and mirror the data onto other disks.However, the illustration above of RAID 1_0, is not the best way

of configuring that type of RAID Group. The next slide will go into

detail as to why this isn’t the best method of configuring RAID

1_0.

RAID 3 – Striping Data with a Dedicated Parity Drive. This

type of RAID Group allows the Clariion to stripe data the first X

number of disks in the RAID Group, and dedicate the last disk in

the RAID Group for Parity of the data stripe. In the event of a

single drive failure in this RAID Group, the failed disk can be

rebuilt from the remaining disks in the RAID Group.

RAID 5 – Striping Data with Distributed Parity . RAID type 5

allows the Clariion to distribute the Parity information to rebuild

a failed disk across the disks that make up the RAID Group. As in

RAID 3, in the event of a single drive failure in this RAID Group,

the failed disk can be rebuilt from the remaining disks in the

RAID Group.

RAID 6 – Striping Data with Double Parity . This is new to

Clariion world starting in Flare Code 26 of Navisphere. The

simplest explanation of RAID 6 we can use for RAID 6 is the RAID

Group uses striping, such as RAID 5, with double the parity. This


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allows a RAID 6 RAID Group to be able to have two drive failures

in the RAID Group, while maintaining access to the LUNs.

HOT SPARE – A Dedicated Single Disk that Acts as a Failed

Disk . A Hot Spare is created as a single disk RAID Group, and is

bound/created as a HOT SPARE in Navisphere. The purpose of

this disk is to act as the failed disk in the event of a drive failure.

Once a disk is set as a HOT SPARE, it is always a HOT SPARE,

even after the failed disk is replaced. In the slide above, we list

the steps of a HOT SPARE taking over in the event of a disk

failure in the Clariion.

1. A disk fails – a disk fails in a RAID Group somewhere in the

back of the Clariion.

2. Hot Spare is Invoked – a Clariion dedicated HOT SPARE acts as

the failed disk in Navisphere. It will assume the identity of the

failed disk’s Bus_Enclosure_Disk Address.

3. Data is REBUILT Completely onto the Hot Spare from the other

disks in the RAID Group – The Clariion begins to recalculate and

rebuild the failed disk onto the Hot Spare from the other disks in

the RAID Group, whether it be copying from the MIRRORed copyof the disk, or through parity and data calculations of a RAID 3 or

RAID 5 Group.

4. Disk is replaced – Somewhere throughout the process, the

failed drive is replaced.

5. Data is Copied back to new disk – The data is then copied back

to the new disk that was replaced. This will take place

automatically, and will not begin until the failed disk is

completely rebuilt onto the Hot Spare.

6. Hot Spare is back to a Hot Spare – Once the data is written

from the Hot Spare back to the failed disk, the Hot Spare goes

back to being a Hot Spare waiting for another disk failure.

Hot Spares are going to be size and drive type specific.

Size. The Hot Spare must be at least the same size as the largest

size disk in the Clariion. A Hot Spare will replace a drive that is

the same size or a smaller size drive. The Clariion does not allow

multiple smaller Hot Spares replace a failed disk.

Drive Type Specific . If your Clariion has a mixture of Drive

Types, such as Fibre and S.ATA disks, you will need Hot Spares of

those particular Drive Types. A Fibre Hot Spare will not replace afailed S.ATA disk and vice versa.

Hot Spares are not assigned to any particular RAID Group. They

are used by the Clariion in the event of any failure of that Drive

Type. The recommendation for Hot Spares is one (1) Hot Spare

for every thirty (30) disks.

There are multiple ways to create a RAID Group. One is via the

Navisphere GUI, and the other is through the Command Line

Interface. In later slides we will l ist the commands to create a

RAID Group.


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Posted by san guy at 1:42 PM 3 comments

The VAULT Drives

Vault Drives

All Clariions have Vault Drives. They are the first five (5) disks in

all Clariions. Disks 0_0_0 through 0_0_4. The Vault drives on the

Clariion are going to contain some internal information that is

pre-configured before you start putting data on the Clariion. The

diagram will show what information is stored on the Vault Disks.

The Vault.

The vault is a ‘save area’ across the first five disks to store write

cache from the Storage Processors in the event of a Power

Failure to the Clariion, or a Storage Processor Failure. The goal

here is to place write cache on disk before the Clari ion powers

off, therefore ensuring that you don’t lose the data that was

committed to the Clariion and acknowledged to the host. The

Clariions have the Standby Power Supplies that will keep the

Storage Processors running as well as the first enclosure of disks

in the event of a power failure. If there is a Storage Processor

Failure, the Clariion will go into a ‘panic’ mode and fear that it

may lose the other Storage Processor. To ensure that it does not

lose write cache data, the Clariion will also dump write cache to

the Vault Drives.

The PSM Lun.

The Persistent Storage Manager Lun stores the configuration of the Clari ion. Such as Disks, Raid Groups, Luns, Access Logix

information, SnapView configuration, MirrorView and SanCopy

configuration as well. When this LUN was first introduced on the

Clariions back on the FC4700s, it used to appear in Navisphere

under the Unowned Luns container as Lun 223-PSM Lun. Users

have not been able to see it in Navisphere for awhile. However,

you can grab the information of the Array’s Configuration by

executing the following command.

naviseccli -h 10.127.35.42 arrayconfig -capture -output

c:\arrayconfig.xml -format XML -schema clariion


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Example of Information retrieved from the File:

For a Disk:

/CLAR:Disk

CLAR:Disk type="Category"

CLAR:Bus type="Property"1/CLAR:Bus

CLAR:Enclosure type="Property"0/CLAR:Enclosure

CLAR:Slot type="Property"12/CLAR:Slot CLAR:State type="Property"3/CLAR:State

CLAR:UserCapacityInBlocks

type="Property"274845/CLAR:UserCapacityInBlocks

For a LUN:

/CLAR:LUN

CLAR:LUN type="Category"

CLAR:Name type="Property"LUN 23/CLAR:Name

CLAR:WWN

type="Property"60:06:01:60:06:C4:1F:00:B1:51:C4:1B:B3:A2:

DC:11/CLAR:WWN

CLAR:Number type="Property"6142/CLAR:Number

CLAR:RAIDType type="Property"1/CLAR:RAIDType

CLAR:RAIDGroupID type="Property"13/CLAR:RAIDGroupID

CLAR:State type="Property"Bound/CLAR:State

CLAR:CurrentOwner type="Property"1/CLAR:CurrentOwner

CLAR:DefaultOwner type="Property”2/CLAR:DefaultOwner

CLAR:Capacity type="Property"2097152/CLAR:Capacity

Flare Database LUN.

The Flare Database LUN will contain the Flare Code that is

running on the Clariion. I like to say that it is the application thatruns on the Storage Processors that allows the SPs to create the

Raid Groups, Bind the LUNs, setup Access Logix, SnapView,

MirrorView, SanCopy, etc…

Operating System.

The Operating System of the Storage Processors is stored to the

first five drives of the Clariion.

Now, please understand that this information is NOT in any way

shape or form laid out this way across these disks. We are only

seeing that this information is built onto these first five drives of

the Clariion. This information does take up disk space as well.

The amount of disk space that it takes up per drive is going to

depend on what Flare Code the Clariion is running. Clariions

running Flare Code 19 and lower, will lose approximately 6 GB of

space per disk. Clariions running Flare Code 24 and up, will lose

approximately 33 GB of space per disk. So, on a 300 GB fibre

drive, the actual raw capacity of the drive is 268.4 GB. Also, you

would subtract another 33 GB per disk for this Vault/PSM

LUN/Flare Database LUN/Operating System Information. That

would leave you with about 235 GB per disk on the first five

disks.


clariion blogs_ january 2008 lun's

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