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146 IBM System Storage DS6000 Series: Copy Services with IBM System z
13.7 Distance
The distance between your primary and secondary DS6000 subsystems will have an effect
on the response time overhead of the Metro Mirror implementation. The maximum supported
distance for Metro Mirror is 300 km.
13.8 Symmetrical configuration
When planning your Metro Mirror configuration, consider the possibility of a symmetrical
configuration, in terms of both physical and logical elements. This will have the following
benefits:
Simplifying management. It is easier to see where volumes will be mirrored, and
processes can be easily automated.
Reducing administrator overhead. Due to automation, and the simpler nature of the
solution, overhead can be reduced.
Simplifying the addition of new capacity into the environment. New arrays can be added in
a modular fashion.
Easing problem diagnosis. The simple structure of the solution will aid in identifying where
any problems may exist.
Figure 13-8 shows this idea in a graphical form.
Figure 13-8 Symmetrical Metro Mirror configuration
As shown in Figure 13-8, DS6000 #1 has Metro Mirror paths defined to DS6000 # 2, which is
in a remote location. On DS6000 #1, volumes defined in LSS 00 are mirrored to volumes in
LSS 00 on DS6000 #2 (volume P1 is paired with volume S1, P2 with S2, P3 with S3, and so
on). Volumes in LSS 01 on DS6000 #1 are mirrored to volumes in LSS 01 on DS6000 #2, and
so on.
Requirements for additional capacity can be added in a symmetrical way also: by the addition
of volumes into existing LSSs, and by the addition of new LSSs when needed (for example,
addition of two volumes in LSS 03 and 05, and one volume to LSS 04 will bring them to the
same number of volumes as the other LSS). Additional volumes could then be distributed
evenly across all LSSs, or additional LSSs could be added.
LSS
00
LSS
02
LSS
04
LSS
01
LSS
03
LSS
05
LSS
00
LSS
02
LSS
04
LSS
05
LSS
03
LSS
01
DS6000 #1 DS6000 #2
P1
P2 P3
P7 P8
P4
P9
P5
P6
P10
P11
P12
P13
S1
S2 S3 S4 S5 S6
S7 S8 S9
S10
S11 S12
S13