User`s guide

Appendix B: Understanding RAID ● 86

RAID 50 Arrays

A RAID 50 array is built from six to forty-eight disk drives configured as

two or more RAID 5 arrays, and stripes stored data and parity data

across all disk drives in both RAID 5 arrays. (For more information, see

RAID 5 Arrays on page 84.)

Note: Because the Adaptec 2420SA RAID controller can’t support more

than four disk drives, it can’t support RAID 50 arrays.

The parity data provides data protection, and striping improves

performance. RAID 50 arrays also provide high data transfer speeds.

Drive segment size is limited to the size of the smallest disk drive in the

array. For example, three 250 GB disk drives and three 400 GB disk

drives comprise two equal-sized RAID 5 arrays with 500 GB of stored

data and 250 GB of parity data. The RAID 50 array 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 G

1, 5, P 3, P, 9 2, 6, P 4, P, 10P, 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