CMPT 225 Lecture Notes - Quicksort, Sorting Algorithm, Recursive Partitioning
4 Sep 2013
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Document Summary
Hard drive: consists of number of disks, aligned with each other, sit on spindle. Disk head array - series of heads which sit on top of the disks. Disk head reads from one side of one disk at a time. Raid: composed of multiple disk drives, can be read in parallel, depending on raid type. Data in blocks - possible example, 2048 bytes. To read this block, must move disk head to appropriate track. Seek time: in region of 2 to 20 milliseconds - time to move to track you want to read. Reading 1 block from a disk: order of 10ms. Suggests that how you organize things on the disk is very important! Can also call blocks pages, pages are abstractions of blocks, can refer to pages on disk and pages in main memory - same size. Reading one page in ram is in region of 50ns ms = 10^-3s ns = 10^-9s.
