3Ware 9550SX-4LP - Setting the Storsave Profile for a Unit

Setting Unit Policies
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Setting the StorSave Profile for a Unit
You can set the desired level of data protection versus performance for a unit
by selecting the StorSave Profile. Three profiles are provided: Protection
(maximum data protection), Performance (maximum performance, less data
protection), and Balanced (a middle ground).The default is Protection.
Note: If the write cache setting is disabled for a unit, the StorSave
Profile capability does not apply and is automatically disabled.
About StorSave Profile Levels
The three profiles automatically adjust several different factors that affect
protection and performance on a per unit basis. These are summarized in the
table below and further explained after the table.
•
FUA (Force Unit Access). FUA commands are a way that the RAID
controller or a program (such as a database program) can ensure that data
is actually written to the disk drive media, and is not stored in cache.
When a write command is followed with a FUA command, then the disk
drive will only issue “command complete” to the controller once the data
is written to media. When performance is considered more important than
protection, it may be desirable to ignore FUA commands.
Table 8: StorSave Profile Definitions
Protection (Default) Balanced Performance
Definition
Maximum data
protection, but slower
performance.
More data protection
than Performance but
less data protection
than Protection.
Maximum
performance for the
unit, but less data
protection.
FUA (Force Unit
Access)
Honor FUA (If no BBU
is present)
Ignore FUA (If BBU is
present)
Honor FUA (If no BBU
is present)
Ignore FUA (If BBU is
present)
Ignore FUA
Write Journaling
Enabled Disabled, if no BBU
present. (Enabled, if
BBU is present.)
Disabled. (If BBU is
present, this
essentially disables
the BBU for this unit.)
Disable Cache on
Degrade
Enabled Disabled Disabled