HP StorageWorks P2000 HP StorageWorks P2000 G3 MSA System SMU Reference Guide - Page 50

Controlling host access to the system's write-back cache setting - shutdown

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• Illegal Request. Sends a reply that there is a LUN but that the request is "illegal." Sense data returned is a Sense Key of 5h and an ASC/ASCQ of 25/00. 3. Click Apply. Controlling host access to the system's write-back cache setting You can prevent hosts from using SCSI MODE SELECT commands to change the system's write-back cache setting. Some operating systems disable write cache. If host control of write-back cache is disabled, the host cannot modify the cache setting. The default is Disabled. This option is useful in some environments where the host disables the system's write-back cache, resulting in degraded performance. To change host access to the write-back cache setting 1. In the Configuration View panel, right-click the system and select Configuration > Advanced Settings > Cache. 2. Either select (enable) or clear (disable) the Host Control of Write-Back Cache option. 3. Click Apply. Changing auto-write-through cache triggers and behaviors You can set conditions that cause ("trigger") a controller to change the cache mode from write-back to write-through, as described in About volume cache options on page 25. You can also specify actions for the system to take when write-through caching is triggered. To change auto-write-through cache triggers and behaviors 1. In the Configuration View panel, right-click the system and select Configuration > Advanced Settings > Cache. 2. In the Auto-Write Through Cache Trigger Conditions section, either select (enable) or clear (disable) the options: • Controller Failure. Changes to write-through if a controller fails. Disabled by default. • Cache Power. Changes to write-through if cache backup power is not fully charged or fails. Enabled by default. • CompactFlash. Changes to write-through if CompactFlash memory is not detected during POST, fails during POST, or fails while the controller is under operation. Enabled by default. • Power Supply Failure. Changes to write-through if a power supply unit fails. Disabled by default. • Fan Failure. Changes to write-through if a cooling fan fails. Disabled by default. • Overtemperature Failure. Forces a controller shutdown if a temperature is detected that exceeds system threshold limits. Disabled by default. 3. In the Auto-Write Through Cache Behaviors section, either select (enable) or clear (disable) the options: • Revert when Trigger Condition Clears. Changes back to write-back caching after the trigger condition is cleared. Enabled by default. • Notify Other Controller. Notifies the partner controller that a trigger condition occurred. Enable this option to have the partner also change to write-through mode for better data protection. Disable this option to allow the partner continue using its current caching mode for better performance. Disabled by default. 4. Click Apply. 50 Configuring the system

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50
Configuring the system
•
Illegal Request
. Sends a reply that there is a LUN but that the request is “illegal.” Sense data
returned is a Sense Key of
5h
and an ASC/ASCQ of
25/00
.
3.
Click
Apply
.
Controlling host access to the system's write-back cache setting
You can prevent hosts from using
SCSI MODE SELECT
commands to change the system's write-back cache
setting. Some operating systems disable write cache. If host control of write-back cache is disabled, the
host cannot modify the cache setting. The default is Disabled.
This option is useful in some environments where the host disables the system's write-back cache, resulting
in degraded performance.
To change host access to the write-back cache setting
1.
In the Configuration View panel, right-click the system and select
Configuration > Advanced Settings >
Cache
.
2.
Either select (enable) or clear (disable) the
Host Control of Write-Back Cache
option.
3.
Click
Apply
.
Changing auto-write-through cache triggers and behaviors
You can set conditions that cause (“trigger”) a controller to change the cache mode from write-back to
write-through, as described in
About volume cache options
on page 25. You can also specify actions for
the system to take when write-through caching is triggered.
To change auto-write-through cache triggers and behaviors
1.
In the Configuration View panel, right-click the system and select
Configuration > Advanced Settings >
Cache
.
2.
In the Auto-Write Through Cache Trigger Conditions section, either select (enable) or clear (disable) the
options:
•
Controller Failure
. Changes to write-through if a controller fails. Disabled by default.
•
Cache Power
. Changes to write-through if cache backup power is not fully charged or fails. Enabled
by default.
•
CompactFlash
. Changes to write-through if CompactFlash memory is not detected during POST, fails
during POST, or fails while the controller is under operation. Enabled by default.
•
Power Supply Failure
. Changes to write-through if a power supply unit fails. Disabled by default.
•
Fan Failure
. Changes to write-through if a cooling fan fails. Disabled by default.
•
Overtemperature Failure
. Forces a controller shutdown if a temperature is detected that exceeds
system threshold limits. Disabled by default.
3.
In the Auto-Write Through Cache Behaviors section, either select (enable) or clear (disable) the options:
•
Revert when Trigger Condition Clears
. Changes back to write-back caching after the trigger
condition is cleared. Enabled by default.
•
Notify Other Controller
. Notifies the partner controller that a trigger condition occurred. Enable this
option to have the partner also change to write-through mode for better data protection. Disable
this option to allow the partner continue using its current caching mode for better performance.
Disabled by default.
4.
Click
Apply
.