Avago Technologies MegaRAID Fast Path Software - Manual (Page 82)

Page 82 LSI Corporation Confidential | July 2011
MegaRAID SAS Software User Guide Chapter 4: WebBIOS Configuration Utility | Creating a Storage Configuration
4.5.2.4 Using Manual
Configuration: RAID 6
RAID 6 is similar to RAID 5 (drive striping and distributed parity), except that instead of
one parity block per stripe, there are two. With two independent parity blocks, RAID 6
can survive the loss of any two drives in a virtual drive without losing data. Use RAID 6
for data that requires a very high level of protection from loss.
RAID 6 is best suited for networks that perform a lot of small input/output (I/O)
transactions simultaneously. It provides data redundancy, high read rates, and good
performance in most environments.
In the case of a failure of one drive or two drives in a virtual drive, the RAID controller
uses the parity blocks to recreate all of the missing information. If two drives in a RAID 6
virtual drive fail, two drive rebuilds are required, one for each drive. These rebuilds do
not occur at the same time. The controller rebuilds one failed drive, and then the other
failed drive.
NOTE: Integrated MegaRAID displays new drives as Just a Bunch of Disks (JBOD). For
MegaRAID, unless the inserted drive contains valid DDF metadata, new drives display as
JBOD. Rebuilds start only on Unconfigured Good drives, so you have to change the new
drive state from JBOD to Unconfigured Good to start a rebuild.
When you select Manual Configuration, and click Next, the WebBIOS Drive Group
Definition dialog appears. You use this dialog to select drives to create drive groups.
1. Hold Ctrl while selecting at least three ready drives in the Drives panel on the left.
2. Click Add To Array to move the drives to a proposed drive group configuration in
the Drive Groups panel on the right, as shown in Figure 41 .
3. If you need to undo the changes, click Reclaim.
4. Choose weather to use power save mode.
5. Choose whether to use drive encryption.
The drop-down list in the Encryption field lists the options.