Dell PowerFlex 4.5.x Technical Overview

Rebalance

When PowerFlex detects that user data is not balanced across devices in the storage pool, it initiates a process to restore the balance in which data copies are moved from the most used devices to the least used.

Rebalance is the process of moving one of the data copies to a different server. It occurs when PowerFlex detects that the user data is not evenly balanced across the fault units in a storage pool. This can occur as a result of several conditions such as: SDS addition or removal, device addition/removal, or following a recovery from a failure. PowerFlex moves copies of the data from the most used devices to the least used ones.

Both rebuild and rebalance compete with the application I/O for the system resources, which include network, CPU and disks. PowerFlex provides a rich set of parameters that can control this resource consumption. While the system is factory-tuned for balancing between speedy rebuild or rebalance and minimization of the effect on the application I/O, the user has fine-grain control over the rebuild and rebalance behavior.