Dell PowerVault ME4 Series Storage System Administrator’s Guide

Change auto-write-through cache triggers and behaviors

1. In the System topic, select Action > Advanced Settings > Cache.
2. In the Auto-Write Through Cache Trigger Conditions section, either select to enable or clear to disable the options:

   Auto-Write Through Cache Trigger Conditions options

   Controller Failure	Changes to write-through if a controller fails. In a dual-controller system this option is disabledby default. In Single Controller mode this option is grayed out.
   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.
   Over-temperature 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 to enable or clear to disable the options:

   Auto-Write Through Cache Behaviors options

   Revert when Trigger Condition Clears	When enabled, the cache policy changes back to write-back caching after the trigger condition is cleared. When disabled, the cache policy remains write-through 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 to continue using its current caching mode for better performance. In a dual-controller system this option is disabled by default. In Single Controller mode this option is grayed out.

4. Click Apply. If you disabled Cache Power or CompactFlash, a confirmation prompt appears. Choose Apply to accept the changes, or Cancel to discard the changes.