Adaptec 5405 User Guide - Page 159

RAID 50 Logical Drives, example

Page 159 highlights

Appendix B: Selecting the Best RAID Level ● 159 RAID 50 Logical Drives A RAID 50 logical drive is built from at least six disk drives configured as two or 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 157.) 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. RAID 50 Logical Drive = 1000 GB plus Parity RAID 5 A Each RAID 5 Logical Drive has 500 GB Data Storage 250 GB Parity Data RAID 5 B 1, 5, P 3, P, 9 P, 7, 11 Drive 1 250 GB Drive 2 250 GB Drive 3 250 GB 2, 6, P 4, P, 10 P, 8, 12 Total Unused Space = 150 GB Drive 4 400 GB Drive 5 400 GB Drive 6 400 GB In this example, P represents the distributed parity data.

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Appendix B: Selecting the Best RAID Level
159
RAID 50 Logical Drives
A RAID 50 logical drive is built from at least six disk drives configured as two or 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 157
.)
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 this example, P represents the distributed parity data.
RAID 5
B
RAID 50 Logical
Drive
=
1000 GB
plus Parity
RAID 5
A
Each RAID 5 Logical Drive has
500 GB Data Storage
250 GB Parity Data
Drive 1
250 GB
Drive 2
250 GB
Drive 3
250 GB
Drive 4
400 GB
Drive 5
400 GB
Drive 6
400 GB
1, 5, P
3, P, 9
P, 7, 11
2, 6, P
4, P, 10
P, 8, 12
Total Unused
Space = 150 GB