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MegaRAID SAS Software User Guide Chapter 4: WebBIOS Configuration Utility
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Creating a Storage Configuration
Figure 36: WebBIOS Virtual Drive Definition Screen
7. 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 1.
— 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. This is the default.
Read Only : Allow read-only access.
Blocked : Do not allow access.
— Read Policy: Specify the read policy for this virtual drive:
Normal : This option disables the read ahead capability. This is the default.
Ahead: This option 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.