Dell 3 - Manual (Page 168)

166 PERC 3 BIOS Configuration Utility
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Stripe Size specifies the size of the segments written to each disk in a
RAID 1 or 5 logical drive. You can set the stripe size to 2 KB, 4 KB,
8 KB, 16 KB, 32 KB, 64 KB, or 128 KB. A larger stripe size produces
better read performance, especially if your computer does mostly
sequential reads. If you are sure that your computer does random read
requests more often, choose a small stripe size. The default is 64 KB.
12 Set the Write Policy from the Advanced Menu.
Write Policy sets the caching method to write-back or write-through.
NOTE: In Cluster mode,
PERC 3/DC allows write-
through cache policy only.
– In Write-back caching, the controller sends a data transfer
completion signal to the host when the controller cache has
received all the data in a transaction. This setting is recommended
in standard mode.
– In Write-through caching, the controller sends a data transfer
completion signal to the host when the disk subsystem has
received all the data in a transaction. This is the default setting if
cluster mode is enabled.
Write-through caching has a data security advantage over write-back
caching. Write-back caching has a performance advantage over write-
through caching.
13 Set the Read Policy from the Advanced Menu.
The Read-ahead option enables the SCSI read-ahead feature for the
logical drive. You can set this parameter to No-Read-Ahead, Read-
ahead, or Adaptive. Adaptive is the default setting.
– No-Read-Ahead specifies that the controller does not use read-
ahead for the current logical drive.
– Read-ahead specifies that the controller uses read-ahead for the
current logical drive.
– Adaptive specifies that the controller begins using read-ahead if
the two most recent disk accesses occurred in sequential sectors. If
all read requests are random, the algorithm reverts to No-Read-
Ahead, however, all requests are still evaluated for possible
sequential operation.
14 Set the Read Policy from the Advanced Menu.
Cache Policy applies to reads on a specific logical drive. It does not
affect the Read-ahead cache.
– Cached I/O specifies that all reads are buffered in cache memory.