3Ware 9550SXU-12 User Guide - Page 130

Configuring Units Figure 55. Unit Policies on Controller Settings Page in 3DM Enabling and Disabling the Unit Write Cache Write cache is used to store data locally in memory on the controller before it is written to the disk drive media, allowing the computer to continue with its next task. This improves performance. However, there may be instances when you want the computer to wait for the drive to write all the data to disk before going on to its next task. In this case, you must disable the write cache. Note: If write cache is enabled, in the event of a power failure, the data in the controller cache will be lost if you do not have a Battery Backup Unit (BBU). To avoid a sudden power failure if you do not have a BBU, it is advisable to have an Uninterruptible Power Supply (UPS). Write cache can be turned on or off for individual units in 3DM, CLI, and 3BM without changing the configuration or losing data from the drives. 118 3ware SAS/SATA RAID Software User Guide, Version 9.5.1