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Department of Electronics
Advanced Information Storage
05
Atsufumi Hirohata
15:00 21/October/2013 Monday (P/L 005)
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Quick Review over the Last Lecture
Logical conjunctions :
• AND
• OR
• NOT
• NAND
• NOR
• XOR
Venn diagrams :
A B
Notations :
• ¬A (Ā)
• AB
• A↑B
• A∧B
• A⊕B
• A∨B
Logic circuits :
A B
A Ā
A B
A B
A B
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05 Magnetic Tape Storage 1
• Advantages
• Development
• Linear recording
• Helical recording
• 1 / 2 reel
• Linear tape open
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Access Patterns to a Hard Disk Drive
Research on access patterns on network attached storages (NAS) : *
* http://www.oracle.com/
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Origins of Data Loss
Information storage is required : *
* http://www.oracle.com/
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Why Tape Storage ?
Magnetic tape media : *
3-times-more data are stored as compared with a hard disk drives (HDD).
Almost 20 EB data are stored in tape media
* http://home.jeita.or.jp/
Almost 25M tapes !
Tapes
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Data Transfer Speed
Magnetic tape media : *
Without compression, 160 MB / sec. (576 GB / h).
Almost comparable with a HDD
* http://home.jeita.or.jp/
HDD
Tapes
Optical disks
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Where are Magnetic Storages Used ?
World-wide enterprise disk storage consumption : *
* http://home.jeita.or.jp/
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Energy Consumption
Energy costs : *
Tape media : LTO-5 without compression
Initial 3 PB data + 45 % annual increase for 12 years
* http://home.jeita.or.jp/
Total cost of ownership (TCO) : 1/15 of HDD
Energy cost : 1/238 of HDD
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Economics of Modern Storage
Multi-tiered storage can be economical : *
* http://www.oracle.com/
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First Magnetic Tape Drive
In 1951, Remington Rand introduced the first tape drive for a computer : *
* http://www.wikipedia.org/
UNIVAC (Universal automatic computer) I uses a tape drive, UNISERVO.
•½-inch wide tape
•Nickel-plated phosphor bronze (Vicalloy)
•1,200 feet long
•8 channels (6 for data, 1 for parity and 1 for timing)
•100 inch / sec. (= 12,800 characters / sec.)
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IBM 7 Tracks
In 1952, IBM also introduced a magnetic tape storage : *
* http://www.wikipedia.org/
• ½-inch wide tape
• 1,400 feet long
• 7 channels (6 for data and 1 for parity)
• 75 inch / sec. (= 7,500 characters / sec.)
• 6-bit characters
In 1964, IBM introduced a 9 tracks : *
• ½-inch wide tape
• 2,400 feet long
• 9 channels (8 for data and 1 for parity)
• 200 inch / sec. (320 kB / sec.)
• 8-bit characters
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Linear Recording Method
* http://www.wikipedia.org/
Linear recording :
• Data in long parallel tracks up to the tape length
• Multiple heads simultaneously write / read
• Very simple configuration
• Very low data density
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Linear Serpentine Recording
In 1984, DEC introduced Digital Linear Tape (DLT) : *
* http://www.wikipedia.org/
• ½-inch wide tape
• Compac Tape I cartridge
• 45 kB / sec.
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Helical Scan Recording
In 1956, Toshiba developed the first helical scan recording for a video tape recorder : *
* http://www.wikipedia.org/
• Tilt read / write head (drum)
• High-density recording
* http://www.labguysworld.com/Cat_Toshiba.htm
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Advanced Intelligent Tape
In 1996, Sony introduced Advanced Intelligent Tape (AIT) : *
* http://www.wikipedia.org/
• 8-mm wide tape
• 25 ~ 800 GB (without compression)
• 3 ~ 45 MB / sec. (without compression)
• Memory in cassette (MIC) : 64-kbit Electrically erasable programmable read-only memory (EEPROM) stores usage history and data address.
Fast operation
• Adaptive lossless data compression (ALDC) : Data compression ~ 1/2.6.
High recording density
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Digital Data Storage
* http://www.itmedia.co.jp/enterprise/articles/0607/13/news034.html
In 1987, Sony introduced Digital Audio Tape (DAT) : *
Digital Data Storage (DDS) was then developed in 1989.
•0.15-inch (3.81-mm) or 8-mm wide tape
•60 ~ 170 m long
•2 write heads at 6° angle with 9,000 rpm
•~ 15 mm / sec. (0.18 ~ 12 MB / sec.)• > 17M units shipped
• ~ 50 % in magnetic tape storage
Head
Head cleanerMode motor
Head cleaner(under the plate)
Head
Capstan roller
Guiding roller
Cassette cartridge
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Minimisation of Bit Errors
2 read / write heads : *
Two adjacent tracks with their azimuth angle at ± 20°
* http://www.itmedia.co.jp/enterprise/articles/0607/13/news034.html
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Head Configuration
2 pairs of read / write heads : *
* http://www.itmedia.co.jp/enterprise/articles/0607/13/news034.html
Magnetic ferrite core
Metal-in-gap layer Glass
Non-magnetic ceramics
Gap length
Data track width (DAT 72 = 5.4 m)
Magnetic lamination
Write head Read head
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Development of a DDS
Capacity doubles every 3 year : *
* http://www.itmedia.co.jp/enterprise/articles/0607/13/news034.html
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Tape Cartridges
One reel : *
* http://itpro.nikkeibp.co.jp/article/lecture/20061220/257427/
• Tape is loaded into the system.
Two reels : *
• Tape is loaded into the system.
• Tape is not loaded into the system.
Head
Exposed to a head
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Linear Tape Open
In 2000, IBM, HP and Seagate introduced Linear Tape Open (LTO) : *
* http://www.wikipedia.org/
• Based on research at IBM Tucson Laboratory
• DLT and AIT have dominated the market.
• Accelis :
• 8-mm wide tape
• 2 reels
• High access speed
• Resembles Sony AIT
• Ultrium :
• ½-inch wide tape
• 1 reels and linear scan
• Large storage capacity
• Resembles Quantum DLT
• 100 GB capacity (without compression)
• 20 MB / sec.
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LTO Ultrium Roadmap
* http://www.ultrium.com/
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High Fidelity Operation
Read-while-write : *
Written data is checked by reading out the data immediately after writing.
* http://home.jeita.or.jp/
Head moduleTape motion direction
Tape
Written data
Tracks
Read headWrite head
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Rewrite Operation
In case the read-while-write operation found an error : *
Data is rewritten until the error disappears.
* http://home.jeita.or.jp/
Rewritten data
Tape motion direction
Tape
Written data with an error
Tracks
Rewrite until the error disappears.Write head
Read head
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Data Distribution Operation
Data subsets are repeatedly stored in various tracks : *
Minimises a risk of data loss.
* http://home.jeita.or.jp/
Data subset “0”
Track 1
Error along a track
Error across tracks
Track 2
Track 3
Track 4
Track 5
Track 6
Track 7
Track 8
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Precise Positioning
Data subsets are repeatedly stored in various tracks : *
* http://home.jeita.or.jp/
Tape width~ 1.27 cm
Kagoshima
Distribution in left / right
Data track1280
Tape length ~ 800 m
Sapporo
Surface smoothness
20 μm
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LTO Tape Media
Track width of LTO tape media : *
• 12.65 mm wide tape / 1280 tracks
• Track width : 8.1 m
Smooth base film(PET, PEN or PA)
70 ~ 80 % thickness
Back coating
Bottom non-magnetic layer
Top ferromagnetic layer
Servo-bandServo-signal
320
320
320
320
1280
Track width : 8.1 m
* http://home.jeita.or.jp/