Compaq HSZ80 manual Using Stripesets to Increase I/O Performance

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Using Stripesets to Increase I/O Performance

Stripesets enhance I/O performance by spreading the data across multiple disk drives. Large I/O requests are broken into small segments called “chunks.” These chunks are then “striped” across the disk drives in the storageset, thereby allowing several disk drives to participate in one large I/O request or handle several I/O requests simultaneously.

For example, in a three-member stripeset that contains disk drives 10000, 20000, and 30000, the first chunk of an I/O request is written to 10000, the second to 20000, the third to 30000, the fourth to 10000, and so forth until all of the data has been written to the drives.

		6
1		5
2	3	4

	k
is
D

10000

Disk

20000

Disk

30000

Chunk 1 4 2 5 3 6

CXO5507A

Figure 3–3. Striping Lets Several Disk Drives Participate in Each I/O Request

The relationship between the chunk size and the average request size determines if striping maximizes the request rate or the data-transfer rate. You can set the chunk size or let the controller set it automatically. See “Chunk Size,” page 3–51,for information about setting the chunk size.

Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide