SAN Volume Controller: Best Practices and Performance Guidelines

Chapter 5.8.6. Determining the number of controller ports for DS4000

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74 SAN Volume Controller: Best Practices and Performance Guidelines 5.8.4 Mixing array sizes within an MDG Mixing array sizes within an MDG in general is not of concern. Testing has shown no measurable performance differences between selecting all 6+ p arrays and all 7+ p arrays as opposed to mixing 6+ p and 7+ p arrays. In fact mixing array sizes can actually help balance workload, because it places more data on the ranks that have the extra performance capability provided by the eighth disk. There is one small exposure here in the case where an insufficient number of the larger arrays are available to handle access to the higher capacity. In order to avoid this situation, ...