Appendix A. Overview of IBM System Storage DS5000 RAID types 507
Figure A-1 RAID 0
RAID 1: For availability/good read response time
RAID 1 (Figure A-2) is also known as disk mirroring. It is most suited to applications that
require high data availability, good read response times, and where cost is a secondary issue.
The response time for writes can be somewhat slower than for a single disk, depending on
the write policy. The writes can either be executed in parallel for speed or serially for safety.
Select RAID level 1 for applications with a high percentage of read operations and where cost
is not the major concern.
Figure A-2 RAID 1
Because the data is mirrored, the capacity of the logical drive when assigned RAID level 1 is
50% of the array capacity.
etc.
Block 3
Block 0
Disk 1
etc.
Block 4
Block 1
Disk 2
etc.
Block 5
Block 2
Disk 3
etc.
Block 5
Block 4
Block 3
Block 2
Block 1
Block 0
Logical Drive
Actual
device
mappings
Stripeset
Host view
etc.
Block 2
Block 1
Block 0
Logical Drive
Actual
device
mappings
etc.
Block 2
Block 1
Block 0
Disk 1
etc.
Block 2
Block 1
Block 0
Disk 2
Mirrorset
Host view
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