提纲 Overview of Mass Storage Structure Disk Structure Disk Scheduling(磁盘调度) Disk Management Swap-Space Management RAID(磁盘阵列)Structure 小结和作业 4口”4814在，4色，主)QC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 提纲 Overview of Mass Storage Structure Disk Structure Disk Scheduling (磁盘调度) Disk Management Swap-Space Management RAID (磁盘阵列) Structure 小结和作业
Overview of Mass Storage Structure Magnetic disks(磁盘)provide bulk of secondary storage of modern computers Drives rotate at 60 to 200 times per second Transfer rate(传输速率)is rate at which data flow between drive and computer Positioning time(random-access time)is time to move disk arm to desired cylinder(seek time)and time for desired sector to rotate under the disk head (rotational latency) Head crash results from disk head making contact with the disk surface That's bad Disks can be removable 口”4814在年生”主)QC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of Mass Storage Structure ▶ Magnetic disks (磁盘) provide bulk of secondary storage of modern computers ▶ Drives rotate at 60 to 200 times per second ▶ Transfer rate (传输速率) is rate at which data flow between drive and computer ▶ Positioning time (random-access time) is time to move disk arm to desired cylinder (seek time) and time for desired sector to rotate under the disk head (rotational latency) ▶ Head crash results from disk head making contact with the disk surface ▶ That’s bad ▶ Disks can be removable
Overview of Mass Storage Structure Drive attached to computer via l/O bus Busses vary,including EIDE,ATA,SATA,USB,Fibre Channel,SCSI Host controller in computer uses bus to talk to disk controller built into drive or storage array track t ←-spindle arm assembly Bector s cylinder c- read-write head platter arm rotation 4口”484在4色，主月QC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of Mass Storage Structure ▶ Drive attached to computer via I/O bus ▶ Busses vary, including EIDE, ATA, SATA, USB, Fibre Channel, SCSI ▶ Host controller in computer uses bus to talk to disk controller built into drive or storage array
Overview of Mass Storage Structure sector、 cylinder 4口”484在4色，主月QC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of Mass Storage Structure
Overview of Mass Storage Structure Magnetic tape(磁带) An early secondary-storage medium Relatively permanent and holds large quantities of data Access time slow Random access ~1000 times slower than disk Mainly used for backup,storage of infrequently-used data,transfer medium between systems Kept in spool and wound or rewound past read-write head Once data under head,transfer rates comparable to disk 20-200GB typical storage Common technologies are 4mm,8mm,19mm,LTO-2 and SDLT Oper “口4814在1生主)QC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of Mass Storage Structure ▶ Magnetic tape (磁带) ▶ An early secondary-storage medium ▶ Relatively permanent and holds large quantities of data ▶ Access time slow ▶ Random access ∼1000 times slower than disk ▶ Mainly used for backup, storage of infrequently-used data, transfer medium between systems ▶ Kept in spool and wound or rewound past read-write head ▶ Once data under head, transfer rates comparable to disk ▶ 20-200GB typical storage ▶ Common technologies are 4mm, 8mm, 19mm, LTO-2 and SDLT Oper