Continuous storage vMotion on the cluster

Products

• VMware vCenter Server

Issue/Introduction

Very frequent or excessive tasks being generated on vCenter for storage vMotion to migrate virtual machines across the datastores of the storage cluster.

Environment

vSphere all versions

Cause

Low disk space on the cluster causing Storage DRS (SDRS) to trigger the migrations on trying to balance the datastore utilization.

SDRS will decide the migrations accordingly to the free space and the settings defined on the cluster specially for "I/O latency threshold" and "Space threshold", to allow free space, SDRS can migrate files temporally to a datastore then migrate it again to another datastore until the cluster utilization is balanced.

Resolution

Increase the available space on the cluster by adding more disks or deleting unnecessary files such as unused VMs or old snapshots.

Adjust the Runtime Settings of the Storage DRS to prevent unnecessary balance of the cluster considering the amount of free space available on the datastores and the general size of the virtual machines on it.