User`s guide

60 007-4522-003
4: Using the RAID Controller
RAID Levels
RAID stands for “redundant array of inexpensive disks.” In a RAID storage system,
multiple disk drives are grouped into arrays. Each array is configured as a single system
drive consisting of one or more disk drives.
Correct installation of the disk array and the controller requires a proper understanding
of RAID technology and concepts. The controllers implement several versions of the
Berkeley RAID technology, as summarized in Table 4-1.
Note: Although JBOD (“just a bunch of disks”) is not strictly a RAID level, it is included
at various points in this discussion for comparison to RAID levels. It is sometimes
referred to as RAID 7.
You must select an appropriate RAID level when you define or create system drives. This
decision is based on how you prioritize the following:
Table 4-1 Supported RAID Levels
RAID Level Description
Minimum
Drives
Maximum
Drives Fault-tolerant?
0 Block striping is provided, which yields higher performance than is
possible with individual disk drives. No redundancy is provided.
216No
1 Disk drives are paired and mirrored. All data is duplicated 100% on an
equivalent disk drive.
22Yes
3 Data is striped across several physical disk drives. Parity protection is
used for data redundancy. This level provides a larger bandwidth for
applications that process large files.
316Yes
5 Data and parity information is striped across all physical disk drives.
Parity protection is used for data redundancy.
316Yes
0+1 (6) Combination of RAID levels 0 and 1. Data is striped across several
physical disk drives. This level provides redundancy through mirroring.
416Yes
JBOD (7) Each disk drive is operated independently like a normal disk drive, or
multiple disk drives can be spanned and seen as a single large drive. This
level does not provide data redundancy.
11No