Silicon Graphics Rackable C2110G-RP5 System User's Manual page 50

5: System and Serverboard Information
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• RAID 1
Disk "mirroring", supports exactly two drives. The two drives represent one RAID 1 logical
drive. The operating system will be installed on the drives located in Drive positions 0 and 1.
Note that both drives 0 and 1 must be of the same type, speed and capacity.
• RAID 5
Disk striping with distributed parity - each RAID 5 drive has its own parity resource. Up to
20% of disk space on each drive must be devoted to parity information. A minimum of three
drives are required for a functional RAID 5 array. A single drive failure will result in
decreased performance until the damaged drive is replaced and the parity rebuild is
complete. RAID 5 is generally favored in a "read-heavy" data environment as write
operations will execute at a slower rate. Optional hardware is required to support RAID 5.
Note that all drives must be the same type, speed and capacity.
• RAID 6
RAID 6 enhances RAID 5 style disk striping parity distribution by creating enough parity
data to handle two disk failures. You can lose a disk and have an unrecoverable error (URE)
during reconstruction and still reconstruct your system data. Calculations for the RAID 6
parity stripes are more complicated than those for RAID 5; virtually doubling the workload
for the processor on the RAID controller and exacting a performance penalty on write
operations. Up to 40% of data space on each disk must be devoted to RAID 6 parity
information. Optional hardware is required to support RAID 6 functionality.
Note that all drives must be the same type, speed and capacity.
• RAID 10
Mirrored disk striping, the data is striped across one set of drives and then mirrored on
another set of drives. A minimum of four drives of the same type are required. The total
number of drives must be an even number (4, 6, or 8). A total of four drives is a 2+2 and six
drives is a 3+3, with eight drives being a 4+4 configuration. The operating system will be
striped across all drives in the primary set and then mirrored on the secondary set of drives.
Note that all drives must be the same type, speed and capacity.
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