操作系统原理12章节(946KB).ppt

RAID Levels Operating System Concepts RAID5 example Operating System Concepts /baike/zhujipeijian/yingpang/20100329212286.html RAID 01 vs RAID10 Operating System Concepts /storage/storage-fundamental/raid-10-vs-the-raid-01-raid-1-0-vs-raid-0-1/ Chapter 12: Mass Storage Structure 张竞慧 jhzhang@ Chapter 12: Mass-Storage Systems Disk Structure Disk Attachment Disk Scheduling Disk Management Swap-Space Management RAID Structure Stable-Storage Implementation Tertiary Storage Devices Operating System Issues Performance Issues Operating System Concepts Operating System Concepts Disk Hardware (Cont.) Disk parameters for the original IBM PC floppy disk and a Western Digital WD 18300 hard disk Operating System Concepts Disk Structure Disk drives are addressed as large 1-dimensional arrays of logical blocks, where the logical block is the smallest unit of transfer.  The 1-dimensional array of logical blocks is mapped into the sectors of the disk sequentially. Sector 0 is the first sector of the first track on the outermost cylinder. Mapping proceeds in order through that track, then the rest of the tracks in that cylinder, and then through the rest of the cylinders from outermost to innermost. Operating System Concepts Disk Attachment Disks may be attached one of two ways: Host attached via an I/O port Network attached via a network connection Operating System Concepts Network-Attached Storage Operating System Concepts Storage-Area Network Operating System Concepts Operating System Concepts Disk Scheduling The operating system is responsible for using hardware efficiently — for the disk drives, this means having a fast access time and disk bandwidth. Access time has two major components Seek time is the time for the disk are to move the heads to the cylinder containing the desired sector. Rotational latency is the additional time waiting for the disk to rotate the desired sector to the disk head. Operating System Concepts Disk Scheduling (Cont.) Minimize seek time Seek