Compaq HSZ80 manual Increasing the Request Rate, 52Creating Storagesets

3–52Creating Storagesets

Increasing the Request Rate

A large chunk size (relative to the average request size) increases the request rate by allowing multiple disk drives to respond to multiple requests. If one disk drive contains all of the data for one request, then the other disk drives in the storageset are available to handle other requests. Thus, in principle, separate I/O requests can be handled in parallel, thereby increasing the request rate. This concept is shown in Figure 3–15.

Request A Chunk size = 128k (256 blocks)

Request B

Request C

Request D

CXO-5135A-MC

Figure 3–15. Chunk Size Larger than the Request Size

Applications such as interactive transaction processing, office automation, and file services for general timesharing tend to require high I/O request rates.