Release Notes

28 Dell Virtual Storage Manager: Installation Considerations and Local Data Protection | 2079-BP-V-VSM
Series VASA Provider to find out whether the migration of the VM and its workload would benefit the overall I/O
workload distribution of the PS Series array. If the migration will not result in an improvement in the distribution of the
I/O workload (for example, if the volumes involved reside on the same PS Series group members) the VASA Provider
informs Storage DRS not to perform the migration. Conversely, if the VASA Provider agrees that the migration will
result in an improvement in the distribution of I/O (for example, if the volumes involved reside on different PS Series
group members) the Provider approves the migration request. In this case, Storage DRS leverages Storage vMotion to
move the VM and its I/O workload to the selected datastore.
In another parallel to the VMware classic DRS feature, Storage DRS has the ability to operate in maintenance mode.
When a datastore in a cluster is placed in maintenance mode, the VMs and VMDKs residing on the datastore are
moved to other datastores within the datastore cluster by Storage vMotion. Storage DRS ensures that the I/O workload
and space utilization remains balanced across the remaining datastores that are not in maintenance mode.
Storage DRS also has a placement constraint rule that is enforced during migrations. The first option, enabled by
default, is the Intra-VM VMDK affinity rule which keeps all of a specific VM VMDKs together on the same datastore.
The inverse of that rule, the VMDK anti-affinity rule, keeps the VMDKs of a specific VM on separate datastores within
the datastore cluster. Finally, there is the VM anti-affinity rule which prevents certain VMs from sharing the same
datastore.