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Dell PowerEdge RAID Controller 11 User’s Guide PERC H755, H750, H355, and H350 Controller Series

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Virtual disk write cache policy

The write cache policy of a virtual disk determines how the controller handles writes to the virtual disk.

Table 1. Write cache policiesThe write cache policy of a virtual disk determines how the controller handles writes to the virtual disk.
Feature	Description
Write-back	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. NOTE:The default cache setting for virtual disks is Write-back caching. Write-back caching is also supported for single drive RAID 0 virtual disks.
Write-through	The controller sends a data transfer completion signal to the host system when the disk subsystem has received all the data in a transaction. NOTE:Certain data patterns and configurations perform better with a write-through cache policy.

NOTE:All RAID volumes are presented as write-through to the operating system (Windows and Linux) independent of the actual write cache policy of the virtual disk. PERC cards manage the data in cache independently of the operating system or any applications.

NOTE:Use the Dell OpenManage storage management application or the HII Configuration Utility to view and manage virtual disk cache settings.