Lenovo ThinkServer RD240 MegaRAID SAS Software User Guide - Page 119

Caution: Lenovo allows Writeback mode to be used with or without a battery. It is recommended that you use either a battery to protect the controller cache, or an uninterruptible power supply (UPS) to protect the entire system. If you do not use a battery or a UPS, and there is a power failure, you risk losing the data in the controller cache. • IO Policy: The IO Policy applies to reads on a specific virtual drive. It does not affect the read ahead cache. ◊ Direct: In Direct I/O mode, reads are not buffered in cache memory. Data is transferred to the cache and the host concurrently. If the same data block is read again, it comes from cache memory. This is the default. ◊ Cached: In Cached I/O mode, all reads are buffered in cache memory. • Drive Policy: Specify the drive cache policy: ◊ Enable: Enable the drive cache. ◊ Disable: Disable the drive cache. ◊ NoChange: Leave the current drive cache policy as is. This drive policy is the default. • Disable BGI: Specify the background initialization status: ◊ No: Leave background initialization enabled. This means that a new configuration can be initialized in the background while you use WebBIOS to do other configuration tasks. This is the default. ◊ Yes: Select Yes if you do not want to allow background initializations for configurations on this controller. • Select Size: Specify the size of the virtual drive in megabytes. Normally, this would be the full size for RAID 10 shown in the configuration panel on the right. You may specify a smaller size if you want to create other virtual drives on the same drive group. 16. Click Accept to accept the changes to the virtual drive definition, or click Reclaim to return to the previous settings. 17. When you are finished defining virtual drives, click Next . The Configuration Preview screen appears, as shown in Figure 4.23. Creating a Storage Configuration 4-43