HP Z840 Workstation - Storage Caching Options; Windows Write-caching policy; Intel RSTe write-back cache; LSI SAS Disk Write Caching Policy

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Technical white paper | HP Z840 Workstation
Storage Caching Options
HP Workstations ship with default storage cache settings that balance performance with data protection. The balance of
performance and protection can be adjusted by changing one or more of these settings.
Create a backup of your data before attempting to change any storage related settings.
Windows Write-caching policy (Disk Properties in Disk Manager)
Write caching on the device:
DEFAULT: Enabled
Improves performance by enabling write caching on the disk; however, a loss of power may result in loss of data
that has not been committed to the storage media.
Windows write-cache buer ushing:
DEFAULT: Enabled
When enabled, Windows will periodically instruct the storage device to commit data in the devices cache to the
non-volatile storage media. These periodic commands result in decreased overall system performance.
Note: If Windows write-cache buer ushing is enabled, Intel® RSTe write-back cache is disabled. To enable write-
back cache on volumes, you must disable Windows write-cache buer ushing.
A user can choose to disable Windows write-cache buer ushing to restore system performance, allowing the Intel®
RSTe driver to handle all write-cache buer ushing.
Intel® RSTe write-back cache [for RAID volumes] (Intel RSTe GUI, Volume Properties)
DEFAULT: Disabled
When enabled the read and write performance of a RAID or recovery volume is improved. In write-back cache mode,
the RAID controller acknowledges write I/O requests immediately after the data loads into the controller cache. The
application can continue working without waiting for the data to be physically written to the hard drives.
Enabling Intel® RSTe write-back cache will enable Write caching on the device if not already enabled and will disable
Windows write-cache buer ushing.
LSI SAS Disk Write Caching Policy (Set by rmware and RAID level)
DEFAULT: Disabled for mirrored volumes; Enabled for striped volumes
By default, the Integrated RAID rmware disables disk write caching for mirrored volumes to make sure that the write
journal entry stored in nonvolatile memory is always valid. This setting is not cannot be changed by the user. When a
mirrored array is congured, Write caching on the device is disabled. When a striped array is congured, Write caching
on the device is enabled.
Deleting a mirrored array does not re-enable Write caching on the device.