Department of Electronics Advanced Information Storage 05 Atsufumi Hirohata 15:00 21/October/2013...

transcript

Department of Electronics

Advanced Information Storage

Atsufumi Hirohata

15:00 21/October/2013 Monday (P/L 005)

Quick Review over the Last Lecture

Logical conjunctions :

• AND

• OR

• NOT

• NAND

• NOR

• XOR

Venn diagrams :

Notations :

• ¬A (Ā)

• AB

• A↑B

• A∧B

• A⊕B

• A∨B

Logic circuits :

05 Magnetic Tape Storage 1

• Advantages

• Development

• Linear recording

• Helical recording

• 1 / 2 reel

• Linear tape open

Access Patterns to a Hard Disk Drive

Research on access patterns on network attached storages (NAS) : *

* http://www.oracle.com/

Origins of Data Loss

Information storage is required : *

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 !

Data Transfer Speed

Magnetic tape media : *

Without compression, 160 MB / sec. (576 GB / h).

Almost comparable with a HDD

Optical disks

Where are Magnetic Storages Used ?

World-wide enterprise disk storage consumption : *

Energy Consumption

Energy costs : *

Tape media : LTO-5 without compression

Initial 3 PB data + 45 % annual increase for 12 years

Total cost of ownership (TCO) : 1/15 of HDD

Energy cost : 1/238 of HDD

Economics of Modern Storage

Multi-tiered storage can be economical : *

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.)

IBM 7 Tracks

In 1952, IBM also introduced a magnetic tape storage : *

• 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 : *

• 2,400 feet long

• 9 channels (8 for data and 1 for parity)

• 200 inch / sec. (320 kB / sec.)

• 8-bit characters

Linear Recording Method

Linear recording :

• Data in long parallel tracks up to the tape length

• Multiple heads simultaneously write / read

• Very simple configuration

• Very low data density

Linear Serpentine Recording

In 1984, DEC introduced Digital Linear Tape (DLT) : *

• Compac Tape I cartridge

• 45 kB / sec.

Helical Scan Recording

In 1956, Toshiba developed the first helical scan recording for a video tape recorder : *

• Tilt read / write head (drum)

• High-density recording

* http://www.labguysworld.com/Cat_Toshiba.htm

Advanced Intelligent Tape

In 1996, Sony introduced Advanced Intelligent Tape (AIT) : *

• 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

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 cleanerMode motor

Head cleaner(under the plate)

Capstan roller

Guiding roller

Cassette cartridge

Minimisation of Bit Errors

2 read / write heads : *

Two adjacent tracks with their azimuth angle at ± 20°

Head Configuration

2 pairs of read / write heads : *

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

Development of a DDS

Capacity doubles every 3 year : *

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.

Exposed to a head

Linear Tape Open

In 2000, IBM, HP and Seagate introduced Linear Tape Open (LTO) : *

• 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 :

• 1 reels and linear scan

• Large storage capacity

• Resembles Quantum DLT

• 100 GB capacity (without compression)

• 20 MB / sec.

LTO Ultrium Roadmap

* http://www.ultrium.com/

High Fidelity Operation

Read-while-write : *

Written data is checked by reading out the data immediately after writing.

Head moduleTape motion direction

Written data

Tracks

Read headWrite head

Rewrite Operation

In case the read-while-write operation found an error : *

Data is rewritten until the error disappears.

Rewritten data

Tape motion direction

Written data with an error

Tracks

Rewrite until the error disappears.Write head

Read head

Data Distribution Operation

Data subsets are repeatedly stored in various tracks : *

Minimises a risk of data loss.

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

Precise Positioning

Data subsets are repeatedly stored in various tracks : *

Tape width~ 1.27 cm

Kagoshima

Distribution in left / right

Data track1280

Tape length ~ 800 m

Sapporo

Surface smoothness

20 μm

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

Track width : 8.1 m

Department of Electronics Advanced Information Storage 05 Atsufumi Hirohata 15:00 21/October/2013...

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