Dell Shared PowerEdge RAID Controller 8 Cards For Dell PowerEdge VRTX Systems User’s Guide

In Write-back caching, the controller sends a data transfer completion signal to the host when the controller cache has received all the data in a transaction. The controller then writes the cached data to the storage device in the background.

The risk of using write-back cache is that the cached data can be lost if there is a power failure during or when the data is written to the storage device. This risk is mitigated by using a battery-backed non-volatile cache on the Shared PERC 8 card. See Shared PERC 8 card cache preservation for further information.