How VAO Orchestrates Storage Failover
Storage failover is a process of switching your virtual infrastructure from the source storage system in the production site to the destination storage system in the DR site. During storage failover, fully functional VMs are recovered to the required snapshots on the target storage system — as a result, you can access services and applications you need with minimum disruption.
VAO orchestrates storage failover in the following way when running a storage plan:
- Before VAO starts processing VM groups included in the plan, it performs a number of pre-plan steps to prepare the failover environment:
- VAO runs the VM Power Actions step to shut down source VMs running in the production vCenter Server. To answer VM questions that appear while shutting the VMs down, VAO applies default answers specified in the vCenter Server settings.
The VM Power Actions step has a preconfigured timeout parameter that defines the exact amount of time for the step to execute. If step execution time exceeds the defined parameter value, VAO powers the source VMs off.
- VAO runs the Storage Failover step. It breaks the SnapMirror relationship between the source and destination storage volumes, mounts the destination volumes to the target vCenter Server, and then mounts the recovered datastores to all hosts in the required storage recovery location.
For more information on the way VAO identifies storage recovery locations required to recover datastores, see How VAO Processes Resources.
- When processing VM groups, VAO registers target VMs on hosts in the DR site, and then powers the VMs on.
For more information on the way VAO defines hosts where recovered VMs must be registered, see How VAO Processes Resources.
- After VAO finishes processing VM groups, it performs a number of post-plan steps to finalize the storage failover process:
- VAO runs the Unregister VMs step to unregister source VMs from hosts in the production site.
- VAO runs the Unmount Datastore step to unmount the source volumes from the source vCenter Server.
- [This step applies only if you have selected the Reprotect storage volumes after failover check box at the Protect Volumes step of the Run Plan wizard]
VAO runs the Protect Storage Volumes step to reprotect volumes included in the plan by resynchronizing the data protection relationship in the reverse direction.
When VAO orchestrates storage failover, it handles specific internal elements under the hood — protection groups and storage items:
Protection groups and storage items were introduced into VAO to exclusively support the storage failover process. That is why the VAO UI does not show these elements, but you may come across them in some reports and log entries.