22 Intel
®
RAID Software User’s Guide
Table 11. RAID Levels and Capacity
RAID
Level
Capacity
0 RAID 0 (disk striping) involves partitioning each drive storage space into stripes that can
vary in size. The combined storage space is composed of stripes from each drive. RAID
0 provides maximum storage capacity for a given set of physical disks.
1 or
IME
With RAID 1 (mirroring), data written to one disk drive is simultaneously written to
another disk drive, which doubles the required data storage capacity. This is expensive
because each drive in the system must be duplicated.
5 RAID 5 provides redundancy for one drive failure without duplicating the contents of
entire disk drives. RAID 5 breaks up data into smaller blocks, calculates parity by
performing an exclusive-or on the blocks, then writes the blocks of data and parity to
each drive in the array. The size of each block is determined by the stripe size parameter,
which is set during the creation of the RAID set.
6 RAID 6 provides redundancy for two drive failures without duplicating the contents of
entire disk drives. However, it requires extra capacity because it uses two parity blocks
per stripe. This makes RAID 60 more expensive to implement.
10 RAID 10 requires twice as many drives as all other RAID levels except RAID 1. RAID 10
works well for medium-sized databases or any environment that requires a higher
degree of fault tolerance and moderate to medium capacity. Disk spanning allows
multiple disk drives to function like one big drive. Spanning overcomes lack of disk space
and simplifies storage management by combining existing resources or adding relatively
inexpensive resources.
50 RAID 50 requires two to four times as many parity drives as RAID 5. This RAID level
works best when used with data that requires medium to large capacity.
60 RAID 60 provides redundancy for two drive failures in each RAID set without duplicating
the contents of entire disk drives. However, it requires extra capacity because a RAID 60
virtual disk has to generate two sets of parity data for each write operation. This makes
RAID 60 more expensive to implement.
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