Server Administrator Storage Management 8.3 User’s Guide

Managing The Preserved Cache

The Managed Preserved Cache feature provides you the option to ignore or restore the controller cache data.

In the write-back policy, data is written to the cache before being written to the physical disk. If the virtual disk goes offline or is deleted for any reason, the data in the cache is lost.

Data in the cache may also be lost in case of unintended cable or power failure. If such a failure, Storage Management preserves the data written on the preserved or dirty cache until you recover the virtual disk or clear the cache.

This feature is available only on SAS controllers with firmware version 6.1 and later.

The status of the controller is affected by the preserved cache. The controller status is displayed as degraded if the controller has preserved cache.

CAUTION: You may not be able to use Storage Management to manage the preserved cache in some cases. As an example, consider you have a RAID 1 level with two disks — D1 and D2. If you now remove D2, the virtual disk is degraded and the data in the controller cache is written to D1. So, D1 has the latest data. Now, if you re-insert D2 and pull out D1, the virtual disk is still degraded and does not have the latest data.