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Raid 50 logical drives – Adaptec Storage Manager User Manual

Page 171

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Appendix D: Understanding RAID

170

RAID 50 Logical Drives

A RAID 50 logical drive is built from six to forty-eight disk drives
configured as two ore more RAID 5 logical drives, and stripes stored
data and parity data across all disk drives in both RAID 5 logical drives.
(For more information, see

RAID 5 Logical Drives on page 168

.)

The parity data provides data protection, and striping improves
performance. RAID 50 logical drives also provide high data transfer
speeds.

Drive segment size is limited to the size of the smallest disk drive in the
logical drive. For example, three 250 GB disk drives and three 400 GB
disk drives comprise two equal-sized RAID 5 logical drives with 500 GB
of stored data and 250 GB of parity data. The RAID 50 logical drive can
therefore contain 1000 GB (2 x 500 GB) of stored data and 500 GB of
parity data.

In the example above, P represents the distributed parity data.

RAID 50 Logical Drive = 1000 GB plus Parity

Drive 1

Drive 2

Drive 3

Drive 4

Drive 5

Drive 6

Total Unused

Space = 450 GB

1, 5, P

3, P, 9

2, 6, P

4, P, 10

P, 7, 11

P, 8, 12

250 GB

250 GB

250 GB

400 GB

400 GB

400 GB

500 GB Data Storage each

250 GB Parity Data each

RAID 5

A

RAID 5

B