User's Manual

44 Understanding RAID Concepts
• When a disk fails, the virtual disk still works, but it is operating in a
degraded state. The data is reconstructed from the surviving disks.
• Better read performance, but slower write performance.
• Redundancy for protection of data.
Related Information:
• Organizing Data Storage for Availability and Performance
• Comparing RAID Level and Concatenation Performance
• Controller-supported RAID Levels
• Number of Physical Disks per Virtual Disk
• Maximum Number of Virtual Disks per Controller
RAID Level 6 (Striping with additional distributed parity)
RAID 6 provides data redundancy by using data striping in combination with
parity information. Similar to RAID 5, the parity is distributed within each
stripe. RAID 6, however, uses an additional physical disk to maintain parity,
such that each stripe in the disk group maintains two disk blocks with parity
information. The additional parity provides data protection in the event of
two disk failures. In Figure 3-5, the two sets of parity information are
identified as P and Q.