Lenovo ThinkServer RD330 MegaRAID SAS Software User Guide - Page 98

Chapter 4: WebBIOS Configuration Utility | Creating a Storage Configuration MegaRAID SAS Software User Guide Page 98 Figure 54: WebBIOS Virtual Drive Definition Screen 16. Change the virtual drive options from the defaults listed on the screen as needed. Here are brief explanations of the virtual drive options: - RAID Level: The drop-down menu lists the possible RAID levels for the virtual drive. Select RAID 50. - Strip Size: The strip size is the portion of a stripe that resides on a single drive in the drive group. The stripe consists of the data segments that the RAID controller writes across multiple drives, not including parity drives. For example, consider a stripe that contains 64 KB of drive space and has 16 KB of data residing on each drive in the stripe. In this case, the stripe size is 64 KB and the strip size is 16 KB. You can set the strip size to 8, 16, 32, 64, 128, 256, 512, and 1024 KB. A larger strip size produces higher read performance. If your computer regularly performs random read requests, choose a smaller strip size. The default is 64 KB. - Access Policy: Select the type of data access that is allowed for this virtual drive: RW: Allow read/write access. Read Only: Allow read-only access. This is the default. Blocked: Do not allow access. - Read Policy: Specify the read policy for this virtual drive: Normal: This disables the read ahead capability. This is the default. Ahead: This enables read ahead capability, which allows the controller to read sequentially ahead of requested data and to store the additional data in cache memory, anticipating that the data will be needed soon. This speeds up reads for sequential data, but there is little improvement when accessing random data.