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2. RAID . . 2: . . (CPU registers) (cache memory , SRAM) (main memory, DRAM) - PowerPoint PPT Presentation

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  • 2

    RAID

  • 2: (CPU registers) (cache memory, SRAM) (main memory, DRAM) flash (EEPROM-USB) (magnetic disk, floppy-hard) (optical disk, CD-DVD) (magnetic tape)

  • 2:

  • 2: 1956 IBM RAMAC (random access method for accounting and control) 5 MBytes. RAMAC , bits - , - (storage density) . , , , RAMAC.

  • 2:

  • 2: CPU (controller). . , (bad sectors). CPU :

  • 2: (seek), Tseek: . (rotational latency), Trot: . (transfer) , Ttrans: .: Ttotal = Tseek + rot + trans

  • 2: - (buffer, cache) . : (MTBF), (MTTR)

  • 2:

  • 2: RAID: Redundant Array of Inexpensive/Independent Disks (1988) / . . RAID

  • 2: RAID level 0

  • 2: (mirroring) (shadowing) / R/WRAID level 1

  • 2: bit (data stripping) RAID level 2

  • 2: byte RAID level 3

  • 2: R/W ?RAID level 4

  • 2: RAID level 5

  • 2: RAID5. . .RAID level 6

  • 2: , , . , RAID 0 RAID 1 (RAID 01 RAID 10), . RAID 0 RAID 3 RAID 03 . RAID

  • 2: (optical disk) , , (, , , ). . on-line .

  • 2: :WORM: write-once read-manyRewritable: write-many read-many : CAV : constant angular velocity CLV : constant linear velocity

  • 2: , . , CAV (~100ms 52). : . : . CLV

  • 2: 12cm ( ) . . 1.2mm.

  • 2: .

  • 2: . laser . laser . , . . bits .

  • 2: . , .

  • 2: (zone), (multizone). - . (proximal window). , .

  • 2: . , 52, 52 . (jukebox) - . .

  • 2: 1950 (magnetic tape) - mainframes. 1960 , .

  • 2: , . . - .

  • 2: 9 . bits 6250 bits/ (bpi). / / (read/write speed). . .

  • 2: , ~25g. , . (interrecord gaps). / (start/stop time). - (0.6 ).

  • 2: , , (logical record) . (physical record) . , - . (storage utili-zation factor) .

  • 2: (blocking factor). , , . 8 byte. Hamming byte. bit (parity bit).

  • 2: (even parity) bit 0/1 Hamming . (odd parity) bit 0/1 . bit (vertical) bits. , . - . bytes (longitudinal) bytes.

  • 2: / (linear/longitudinal) (9 /) (serpentine recording) 2 (helical scan) 10-20 VCR (transverse recording) sensors

  • 2: () () ()

  • 2: Jukebox ( TB) ( - ). () . (. MTBF = 250.000 = ~ 29 , 2.000.000 ).

  • 2: : , , . (mass storage): . (magnetic bubble memories): ( 4 7 ms), ( 92.000 1310.720 bits) ( 50.000 5000.000 bps).

  • 2: (semiconductor disks) 1978 - , . ( 0,5 ms), ( 700 b), .

  • 2: (optical tape) - ( 80% 50% , >25 ). (holography) - . (electron trapping), . .

  • 2:

  • 2: Direct attached storage - DASH ( SCSI). - - ( NFS). - - .

  • 2: Network attached storage - NAS - , . . -.

  • 2: Storage area network - SAN - . / / , (switches). .