6.4.2 Datastore Clusters
A datastore cluster is a collection of datastores with shared resources and a shared management interface. Datastore clusters are to datastores what vSphere clusters are to hosts. Datastore cluster is required to use VMware vSphere Storage DRS™ to load balance storage resources.
The following are datastore cluster design considerations:
• Ongoing space balancing on LUNs that are thinly provisioned by the storage array creates unusable white space. VMware vSphere Storage vMotion operation relocates VMs disk (VMDK) files at the vSphere layer. However, the storage array is not aware that the source LUN freed space can be reused. The deleted blocks must be reclaimed manually by running the vmkfstools command from the ESXi CLI prompt.
• A datastore cluster with Storage DRS can simplify datastore management and migrations with Storage DRS maintenance mode. It is, however, no longer possible to manage datastores at individual level (enable/disable, disk thresholds, or VMware vSphere Storage APIs – Array Integration for fast provisioning).
• All datastores in a datastore cluster must belong to the same storage policy.
• Limited NFS 4.1 support.