lec02.468

lec02.468 - Spring 2008 CSC 468 DBMS Implementation...

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. . Spring 2008 CSC 468: DBMS Implementation Alexander Dekhtyar . . Overview of Data Storage Physical Characteristics of Disks A disk drive consists of disk assembly: part of the disk drive that contains the physical data storage. head assembly: part of the disk drive that contains heads for accessing data. Disk assembly consists of disk platters. Each platter has two surfaces. Disk surfaces are partitioned into circular track , each consisting of a number of sectors . A collection of tracks equidistant from the center on all surfaces is called a cylinder . (in other words: the tracks that are under the disk head at the same time). Disk Access A disk block or page is a logical unit of data storage which can be read from disk in a single disk access command . Often a disk block is equal in size to a disk sector, or a small number of disk sectors (2,3,4). Disk latency : time between a disk access command is issued and the data is de- livered from disk to main memory. Disk latency consists of the following compo-
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This note was uploaded on 05/19/2008 for the course CSC 468 taught by Professor Dehktyar during the Spring '08 term at Cal Poly.

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lec02.468 - Spring 2008 CSC 468 DBMS Implementation...

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