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Chapter 9. Configuration planning 179
Figure 9-11 Sparing example 3: RAID-5 - Different capacity, same RPM
Figure 9-11 illustrates an intermix configuration in a DA pair.
1. At first, four RAID-5 arrays with 146 GB DDMs are installed in a DA pair. Each array needs
a spare disk drive (6+P+S). Two spare disks are in one loop and other two spare disks are
in the other loop in the DA pairs.
2. Next, two RAID-5 arrays with 300 GB DDMs are added in the DA pair. According to the
rule of
Minimum 4 spare disks of the largest capacity array site on the DA pair, an
additional 2 arrays need a spare disk (6+P+S).
3. If you add other arrays with 300 GB DDMs, you need spare disks in additional arrays. You
need a total of four 300 GB spare disks in the DA pair; then, two 6+P+S arrays are needed
for RAID-5, and one 3x2+2S array is needed for RAID-10.
Note: Intermix of DDM size and RPM configuration is planned for the future.
Sparing Example 3 – RAID-5:
1
st
4 arrays 146GB & next 2 arrays 300GB (same RPM)
• Assumes all devices same RPM
• Minimum of 4 spares per DA pair
– 2 spares per loop & 2 spares in each array group
– Additional 146GB RAID arrays will be 7 + P (RAID-5) or 4x2 (RAID-10)
• Minimum 4 spares of the largest capacity array site on the DA pair
– Next 2 300GB arrays will also be 6 + P (if RAID-5)
• If next 300GB array configured is RAID-10, then that array will be 3x2 and
any additional 300GB arrays on this DA pair will not have spares
• All spares available to all arrays on the DA pair
1
2
3
4
DA
DA
…
…
6 + P
Array
6 + P
Array
6 + P
Array
6 + P
Array
6
5
6 + P
Array
6 + P
Array
300GB
300GB146GB
146GB
146GB
146GB