Q: How often is vSphere Storage DRS's imbalance calculation invoked?

A:By default, the I/O load-balancing algorithm used by Storage DRS is invoked every eight hours. You might think this is a relatively long period oftime; however, recall that Storage DRS's load balancing requires quite a bit more activity than does virtual machine (VM) load balancing withtraditional DRS. Entire disk files must be migrated between volumes for a Storage vMotion to complete, a process that takes far longer than relocatingVM memory for a traditional vMotion.

VMware recommends against changing the invocation period from its default. A longer period reduces the impact of Storage DRS's activities, but couldlead to greater imbalance. On the other hand, the increased activities associated with a shorter period could have an impact on VM performance.