Using array-based snapshots is an effective way to protect virtual machine data and establish an RPO. In the PowerStore architecture, you can create the snapshot schedule using protection policies. Each protection policy can define snapshot rules to establish a schedule and retention, and replication rules to specify a destination array and RPO.
Figure 27. Protection policies screen in PowerStore Manager
PowerStore has data-recovery mechanisms that behave differently depending on the usage scenario (see the following figure).
- Snapshot: These represent a specific point in time for data stored on a volume that can be used for recoveries to refresh, restore, or create thin clones.
- Thin clone: This takes an existing snapshot from a parent volume and creates a child volume from that point in time.
- Refresh: This allows snapshot data to replace existing data in the volume. The existing data is removed, and snapshot data from the new source is copied to it in-place. A parent volume can refresh a child, and a child can refresh a parent.
- Restore: The restore operation replaces the contents of a parent storage resource with data from an associated snapshot. Restoring resets the data in the parent storage resource to the point in time the snapshot was taken.
Caution: Using the refresh and restore operations on active virtual machine volumes may cause unexpected results and behaviors. All host access to the volume must cease before attempting these operations.
Figure 28. PowerStore snapshot and recovery
If a virtual machine residing on a VMFS datastore requires recovery, the best practice is to create a thin clone from a snapshot. The high-level steps are as follows:
- In PowerStore Manager, create a thin clone from a snapshot, and present it to the vSphere cluster.
- In the vSphere client, rescan the storage, add a datastore, select the newly created volume, and assign a new signature (see the following figure).
- Register the VM from the snap-xxxxxxxx-originaldatastorename datastore.
- Use Storage vMotion to migrate the virtual machine back to the original datastore, if applicable.
Figure 29. New datastore wizard > Assign a new signature