Department of Electronics Advanced Information Storage 05 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 : A B Notations : ¬A (Ā) AB A ↑ B A ∧ B A ⊕ B A ∨ B Logic circuits : A B A Ā A B A B A B

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) : * *

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 *  Almost 25M tapes ! Tapes

Data Transfer Speed Magnetic tape media : * Without compression, 160 MB / sec. (576 GB / h). Almost comparable with a HDD * HDD Tapes 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 : * * 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 : * 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

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) : * * ½-inch wide tape 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 *

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 * In 1987, Sony introduced Digital Audio Tape (DAT) : * Digital Data Storage (DDS) was then developed in 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 cleaner Mode motor Head cleaner (under the plate) Head 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 : * * 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

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 : ½-inch wide tape 1 reels and linear scan Large storage capacity Resembles Quantum DLT 100 GB capacity (without compression) 20 MB / sec.

LTO Ultrium Roadmap *

High Fidelity Operation Read-while-write : * Written data is checked by reading out the data immediately after writing. * Head module Tape motion direction Tape 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 Tape 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 track 1280 Tape length ~ 800 m Sapporo Surface smoothness 20 μ m

LTO Tape Media Track width of LTO tape media : * 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-band Servo-signal Track width : 8.1 m *