User's Manual

RAID 1 characteristics:
• Groups n + n disks as one virtual disk with the capacity of n disks. The controllers currently supported
by Storage Management allow the selection of two disks when creating a RAID 1. Because these disks
are mirrored, the total storage capacity is equal to one disk.
• Data is replicated on both the disks.
• When a disk fails, the virtual disk still works. The data is read from the mirror of the failed disk.
• Better read performance, but slightly slower write performance.
• Redundancy for protection of data.
• RAID 1 is more expensive in terms of disk space since twice the number of disks are used than
required to store the data without redundancy.
RAID Level 5 (Striping With Distributed Parity)
RAID 5 provides data redundancy by using data striping in combination with parity information. Rather
than dedicating a physical disk to parity, the parity information is striped across all physical disks in the
disk group.
RAID 5 characteristics:
• Groups n disks as one large virtual disk with a capacity of (n-1) disks.
• Redundant information (parity) is alternately stored on all disks.
• 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.
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.
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