User`s guide

Disk Topologies
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Configuring for Maximum Performance
Table 4-5 presents the relative performance advantages of each RAID level.
Disk Topologies
After you have determined the RAID level to use, determine the loop configuration. Note
the following:
• The largest RAID group that can be created is 15+1 (16 drives).
• For a tower, the maximum SGI supported configuration is 16 drives total, those in
the system itself; no expansion to another enclosure or tower is possible.
• For a RAID enclosure and two expansion enclosures, the maximum release 5
configuration is 32 drives. A maximum of 16 system drives can be created (see
“System Drives” on page 68 for more information).
0+1 Mirrored and striped Data is striped across multiple disk drives, and written to a mirrored set of disk drives.
JBOD None This configuration offers no redundancy and is not recommended for applications
requiring fault tolerance.
Table 4-5 RAID Levels and Performance
RAID Level Access Profile Characteristics
0 Excellent for all types of I/O activity
1 Excellent for write-intensive applications
3 Excellent for sequential or random reads and sequential writes
5 Excellent for sequential or random reads and sequential writes
0+1 Excellent for write-intensive applications
JBOD Mimics normal, individual disk drive performance characteristics
Table 4-4 RAID Levels and Availability (continued)
RAID Level Fault Tolerance Type Availability