Chapter 12. Performance considerations 275
Figure 12-13 Extent pool affinity to processor complex with one extent pool for each rank
Figure 12-12 also indicates that there is no affinity nor a certain preference between HA and
processor complexes or servers in the DS8000. In this example either one of the two HAs can
address any volume in any of the ranks, which range here from rank number 1 to 12. Note
there is an affinity of DAs to the processor complex. As Figure 12-3 on page 259 depicts, a
DA pair connects to two switches respectively to two pairs of switches. The first DA of this DA
pair connects to the left processor complex or server 0. The second DA of this DA pair
connects to the other processor complex or server 1.
Minimize the number of extent pools
The other extreme is to create just two extent pools when the DS8000 is configured as CKD
storage only. You would then subdivide the disk subsystem evenly between both processor
complexes or servers as Figure 12-13 shows.
RIO-G ModuleRIO-G Module
HA
Extent pool11
Rank
DAs
Extent pool9Extent pool7
Extent pool5Extent pool3
Extent pool1
11
9
7
53
1
8 1210
2
64
Extent pool10Extent pool8Extent pool6
Extent pool4
Extent pool2Extent pool0
RIO-G Module
POWER5 2-way SMP
Server0
Memory
L3
Memory
Processor
Processor
L1,2
Memory
L1,2
Memory
RIO-G Module
POWER5 2-way SMP
Server1
Memory
L3
Memory
Processor
Processor
L1,2
Memory
L1,2
Memory
