SAN Volume Controller: Best Practices and Performance Guidelines

Chapter 9.3.4. Understanding FlashCopy dependencies

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154 SAN Volume Controller: Best Practices and Performance Guidelines 9.3.4 Understanding FlashCopy dependencies With FlashCopy mappings, where each mapping uses the same source VDisk, each mapping has a dependency on other mappings and not on the source VDisk directly. In fact, each target depends on the next target that was started after it, and the last target started is at the top of the dependency tree. With this implementation, the SVC does not need to copy a changed block on the source to up to 16 target VDisks immediately; instead, it copies the change block to the next VDisk in the dependency chain. Figure 9- 4 explains further how the dependency chain works. It is important ...