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M5281/M5283
6. Terminology
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RAID: Redundant Array of Independents Disks.
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RAID 0: Striped Disk Array without Fault Tolerance.
The data is broken down into stripes and each stripe is written to a separate disk drive. This improves the I/O
performance through different drive at different channel. However, it is not fault tolerant. The failure of one disk will
result in data loss in disk array.
The maximum capacity is the number of drives multiply by the minimum size of the drives.
For example, when using 10GB and 14GB drivers to form RAID 0, the RAID 0 capacity is 20GB.
•
RAID 1: Mirroring Disk Array with Fault Tolerance.
The data is written to all drives and read parallel from different drives. This enhances the data protection, but cost
some overhead at performance. Once one drive fails, data can be recovered from other drive.
The maximum capacity is the minimum size of the drives.
For example, when using 10GB and 14GB drivers to form RAID 1, the RAID 1 capacity is 10GB.
•
RAID 0+1: Striping and Mirroring
RAID 0+1 is implemented as a mirrored array whose segments are RAID 0 arrays. RAID 0+1 has same fault
tolerance as mirroring and reduces overhead by striping. It needs at least four drives to form a RAID 0+1.
•
JBOD: Just a Bunch of Drives
JBOD is to expand the capacity of drive through creating a virtual drive which combines more than one disk. The
total capacity is the sum of all drives. The failure of one drive will result in data lost in array.
Revision 0.96
Document Number: M5281-83_RAID096
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