Clearing PERC Cache via OMSA

Sometimes the cache will need to cleared on a PERC in order to create a new Virtual Disk. This can happen for a number of reasons – VD going to an offline state improperly, system shutting down improperly, hard drives going bad, etc.

Here is the OpenMange Server Administrator(OMSA) error message you are likely to encounter when creating a new Virtual Disk:

“The create virtual disk wizard failed to launch. A new virtual disk cannot be created while preserved cache exists. If the failed array can be made healthy, preserved cache can be flushed. If not, discard preserved cache under controller actions and create a new virtual disk.”

Below is an example of the error and how to fix this issue:

NOTE: Clearing the cache can lead to data loss. This should be done if all other options for bringing the Virtual Disk back to an online/optimal state have been exhausted. The below example is of a RAID 0 disk failure. The disk had just been replaced and restoring the VD was not an option.

Clearing_PERC_PERC_Cache_OMSA_1

This picture shows the process to create a new Virtual Disk

Below is the error:

Clearing_PERC_PERC_Cache_OMSA_2

To delete the preserved cache on the PERC we need navigate to the PERC then choose Controller Tasks drop down: Manage Preserved Cache option. Then press the Execute button.

Clearing_PERC_PERC_Cache_OMSA_3

On the next page click Discard Preserved Cache

Clearing_PERC_PERC_Cache_OMSA_4

The cache is now deleted from the PERC and a new Virtual Disk can be created.

Please also note that the cache can be deleted through the PERC BIOS during POST. This will be the only option if your operating system does not boot; meaning OMSA is not accessible… unless the PERC is physically replaced or battery is pulled.

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