HP StorageWorks P2000 HP StorageWorks P2000 G3 MSA System CLI Reference Guide - Page 114

set cache-parameters Description Sets a volume's cache options. Settings you can change include: • Cache write policy • Cache optimization mode • Cache read-ahead size NOTE: Only change the read-ahead cache settings if you fully understand how the host operating system, application, and adapter move data so that you can adjust the settings accordingly. Be prepared to monitor system performance and adjust read-ahead size until you find the optimal size for your application. Syntax set cache-parameters [write-policy write-back|write-through|wb|wt] [optimization standard|super-sequential] [read-ahead-size disabled|default|maximum|64KB|128KB|256KB|512KB|1MB|2MB|4MB |8MB|16MB|32MB] volume Parameters write-policy write-back|write-through|wb|wt Optional. Sets the cache write policy to either: • write-back (wb): Write-back caching does not wait for data to be completely written to disk before signaling the host that the write is complete. This is the preferred setting for a fault-tolerant environment because it improves the performance of write operations and throughput. • write-through (wt): Write-through caching significantly impacts performance by waiting for data to be completely written to disk before signaling the host that the write is complete. Use this setting only when operating in an environment with low or no fault tolerance. optimization standard|super-sequential Optional. Sets the cache optimization mode to either: • standard: Used for applications that read and write small files in random order, such as transaction-based and database update applications. Sets the cache block size to 32 KB. • super-sequential: Used for applications that read and write large files in sequential order, such as video playback and multimedia post-production video and audio editing applications. Sets the cache block size to 128 KB. read-ahead-size Optional. Controls the use and size of read-ahead cache: • disable: Turns off read-ahead cache. • default: Sets one chunk for the first access in a sequential read and one stripe for all subsequent accesses. • maximum: Allows the controller to dynamically calculate the maximum read-ahead cache size for the volume. • 64KB, 128KB, 256KB, 512KB, 1MB, 2MB, 4MB, 8MB, 16MB, 32MB: Sets a specific cache size. volume Name or serial number of the volume to change. For volume syntax, see Command syntax on page 22. Example Set the cache policy and cache optimization mode for volume V1: # set cache-parameters optimization super-sequential read-ahead-size maximum V1 Success: Command completed successfully. - Cache parameters were changed See also • show cache-parameters • show volumes 114