Set Cache-Parameters - HP P2000 Reference Manual

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:
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.
• 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.
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
page 21.
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
124 Alphabetical list of commands
Only change the read-ahead cache settings if you fully understand how the host operating
Command syntax on