IBM System Storage DS3000, Programming Manual

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Table 4-9. Values for the cacheFlushModifier Parameter (continued)
Value Meaning
2
Data is flushed after 2 s.
5
Data is flushed after 5 s.
10
Data is flushed after 10 s.
20
Data is flushed after 20 s.
60
Data is flushed after 60 s (1 min.).
120
Data is flushed after 120 s (2 min.).
300
Data is flushed after 300 s (5 min.).
1200
Data is flushed after 1200 s (20 min.).
3600
Data is flushed after 3600 s (1 hr.).
Infinite
Data in cache is not subject to any age or time constraints.
The data is flushed based on other criteria managed by the
controller.
This example shows how to set this parameter value for all of the logical drives in the storage subsystem:
c:\...\...\client>smcli 123.45.67.89 -c “set alllogicalDrives
cacheFlushModifier=10;”
Important: Do not set the value of the
cacheFlushModifier
parameter above 10 seconds. An exception is
for testing purposes. After running any tests in which you have set the values of the
cacheFlushModifier
parameter above 10 seconds, return the value of the
cacheFlushModifier
parameter to 10 or less seconds.
The
cacheWithoutBatteryEnabled
parameter turns on or turns off the ability of a host to perform write
caching without backup batteries in a controller. To enable write caching without batteries, set this
parameter to
TRUE
. To disable write caching without batteries, set this parameter to
FALSE
. If you set this
parameter to
TRUE
, write caching continues, even when the controller batteries are completely discharged,
not fully charged, or not present. If you do not have an uninterruptible power supply (UPS) and you
enable this parameter, you can lose data if power to the storage subsystem fails.
Note: Attention: Possible loss of data – Because you can lose data when the
cacheWithoutBatteryEnabled
parameter is enabled, IBM recommends that you do not enable this
parameter in a production environment.
This example shows how to set this parameter value:
c:\...\...\client>smcli 123.45.67.89 -c “set logicalDrive
[\”Engineering\”] cacheWithoutBatteryEnabled=FALSE;”
The
mirrorCacheEnabled
parameter turns on or turns off write caching with mirroring. Write caching with
mirroring permits cached data to be mirrored across redundant controllers that have the same cache size.
Data written to the cache memory of one controller is also written to the cache memory of the second
controller. If one controller fails, the second controller can complete all outstanding write operations.
Attention: Possible loss of data – If the
mirrorCacheEnabled
parameter is disabled and one of the
controllers fails, you might lose data that was cached in the failed controller memory but not yet written
to disk. Therefore, IBM recommends that you do not disable this parameter in a production environment.
To use this option, these conditions must exist:
v The controller pair must be an active/active pair.
v
The controllers must have the same size cache.
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IBM System Storage DS3000, DS4000, and DS5000: Command Line Interface and Script Commands Programming Guide