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Table 1-8 “RAID Level Summary for RAID Levels 0 through
5” and Table 1-9 “RAID Level Summary for RAID Levels 1+0 through
5+0” below summarize the features, advantages,
and disadvantages of the various RAID levels. This will assist you
in deciding which RAID level is best for your situation. Table 1-8 RAID Level Summary for RAID Levels 0 through
5 | RAID Level | RAID 0 | RAID 1 | RAID 3 | RAID 5 |
|---|
| Also Known As | striping | mirroring | striping with dedicated parity | striping with distributed parity | | Fault Tolerance | no | yes | yes | yes | | Redundancy Type | none | duplicate | parity | parity | | Hot Spare Option | no | yes | yes | yes | | Disks Required | one or more | two | three or more | three or more | | Usable Capacity | greatest | least | intermediate | intermediate | | Capacity Reduction | none | 50% | capacity of one disk | capacity of one disk | | Read Performance | fast (depends on number of disks) | intermediate | fast | fast | | Random Write Performance | fastest | intermediate | slowest | slow | | Sequential Write Performance | fastest | intermediate | slow | slowest | | Typical Use | Rapid reads and writes with
no need for fault tolerance | Mostly small random writes with fault tolerance | Mostly large, serial transfers with
fault tolerance | Mostly small, random transfers with
fault tolerance |
Table 1-9 RAID Level Summary for RAID Levels 1+0 through
5+0 | RAID Level | RAID 1+0 | RAID 3+0 | RAID 5+0 |
|---|
| Also
Known As | striping with mirrored arrays | striping with dedicated parity drives | striping with distributed parity | | Fault
Tolerance | yes | yes | yes | | Redundancy Type | duplicate | parity | parity | | Hot
Spare Option | yes | yes | yes | | Disks Required for basic RAID | 2 | 3 or more | 3 or more | | | Spans 2 arrays | 4 | 6, 8, 10, 12, 14, or
16 | 6, 8, 10, 12, 14, or
16 | | | Spans 3 Arrays | 6 | 9, 12, 15, 18,
21, or 24 | 9, 12, 15, 18,
21, or 24 | | | Spans 4 arrays | 8 | 12, 16, 20, 24, 28,
or 32 | 12, 16, 20, 24, 28,
or 32 | | | Spans 5 arrays | 10 | 15, 20, 25, 30, 35, or 40 | 15, 20, 25, 30, 35, or 40 | | Usable Capacity | least | intermediate | intermediate | | Capacity Reduction | 50% | capacity of one disk for each array
spanned | capacity of one disk for each array
spanned | | Read Performance | intermediate | fast | fast | | Random
Write Performance | intermediate | slowest | slow | | Sequential Write Performance | intermediate | slow | slowest | | Typical
Use | Mostly small random writes with
fault tolerance and enhanced speed | Mostly large, serial transfers with
fault tolerance and enhanced speed | Mostly small, random transfers
with fault tolerance and enhanced speed |
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