HP StorageWorks 2300 Modular Smart Array reference guide (500911-001, January 2009)

HP StorageWorks 2300 Modular Smart Array reference guide 49
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.
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. The default is Disabled.
• Cache Power. Changes to write-through if cache backup power is not fully charged or fails. The
default is Enabled.
• CompactFlash. Changes to write-through if CompactFlash memory is not detected during POST, fails
during POST, or fails while the controller is under operation. The default is Enabled.
• Power Supply Failure. Changes to write-through if a power supply unit fails. The default is Disabled.
• Fan Failure. Changes to write-through if a cooling fan fails. The default is Disabled.
• Overtemperature Failure. Forces a controller shutdown if a temperature is detected that exceeds
system threshold limits. The default is Disabled.
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. The default is Enabled.
• 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. The
default is Disabled.
4. Click Apply.
Configuring partner firmware update
In a dual-controller system, when you update firmware on one controller, the system also updates the
partner controller. Disable partner firmware update only if requested by a service technician.
To change the partner firmware update setting
1. In the Configuration View panel, right-click the system and select Configuration > Advanced Settings >
Firmware.
2. Either select (enable) or clear (disable) the Partner Firmware Update option.
3. Click Apply.
Configuring system utilities
Configuring background scrub
You can enable or disable whether the system continuously analyzes disks in vdisks to detect, report, and
store information about disk defects. Vdisk-level errors reported include: hard errors, medium errors, and
bad block replacements (BBRs). Disk-level errors reported include: metadata read errors, SMART events
during scrub, bad blocks during scrub, and new disk defects during scrub. For RAID 3, 5, 6, and 50, the
utility checks all parity blocks to find data-parity mismatches. For RAID 1 and 10, the utility compares the
primary and secondary disks to find data inconsistencies. For NRAID and RAID 0, the utility checks for
media errors.
You can use a vdisk while it is being scrubbed. Background scrub always runs at background utility
priority, which reduces to no activity if CPU usage is above a certain percentage or if I/O is occurring on
the vdisk being scrubbed. A background scrub may be in process on multiple vdisks at once. A new vdisk
will first be scrubbed 20 minutes after creation. After a vdisk has been scrubbed, it will not be scrubbed
again for 20 minutes. When a scrub is complete, the number of errors found is reported with event code
207 in the event log.