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Chapter 11. Performance considerations 239
Minimize the number of extent pools
The other extreme is to create just two extent pools when the DS6000 is configured as CKD
storage only. You would then subdivide the disk subsystem evenly between both processor
complexes or servers as Figure 11-13 shows.
Figure 11-13 Extent pool affinity to processor complex with pooled ranks in two extent pools
Again what is obvious here is the affinity between all volumes residing in extent pool 0 to the
left processor complex, server 0, including its HA, and the same for the volumes residing in
extent pool 1 and their affinity to the right processor complex or server 1.
When creating volumes there is no straightforward approach to place certain volumes into
certain ranks. For example, when you create the first 20 DB2 logging volumes, they would be
allocated in a consecutive fashion in the first rank. The concerned RAID site would then host
all these 20 logging volumes. You may have the desire to control the placement of the most
critical performance volumes and also configure for preferred paths. This might lead to a
compromise between both approaches, as Figure 11-14 on page 240 suggests.
Plan for a reasonable number of extent pools
Figure 11-14 presents a grouping of ranks into extent pools which follows a similar pattern
and discussion as for grouping volumes or volume pools into SMS storage groups.
Server 0
Server 1
red I/O
blue I/Ored I/O
blue I/O
preferred pathpreferred path
blue
red
8
6
12
10
4
2
Extent pool1
7
5
11
9
31
Extent pool0
Rank