Chapter 9. Configuration planning 177
9.4.3 Sparing examples
This section provides some examples for configuring each rank according to the rule of
sparing disks.
Figure 9-9 Sparing example 1: RAID-5 - All same capacity, same RPM
In Figure 9-9, four RAID-5 arrays are installed in a DA pair. Each array needs a spare disk
drive (6+P+S). Two spare disks are in one loop and the other two spare disks are in the other
loop in the DA pairs.
If you add other arrays configured with the same capacity and RPM as in this DA pair,
additional arrays will not need spare disks (the arrays will be configured as RAID-5:7+P,
RAID-10:4x2).
Sparing Example 1 – RAID-5:
All same capacity, same RPM
• Assumes all devices same capacity & same RPM
• Minimum of 4 spares per DA pair
– 2 spares per loop & 2 spares in each array group
– Additional RAID-5 arrays will be 7 + P
– Any additional RAID-10 arrays will 4x2
• All spares available to all arrays on DA pair
1
23
4
DA
DA
…
…
6 + P
Array
6 + P
Array
6 + P
Array
6 + P
Array
