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In the first part of this 3-part series, you learnt about Test Failover. In this part, I will talk about the Planned Failover (PFO).
PFO is an operation initiated on the primary VM which allows you to do an e2e validation of your recovery plan. PFO requires the VM to be shut down to ensure consistency.
PFO is *NOT* a substitute for High Availability which is achieved through clustering. PFO allows you to keep your business running with minimal downtime even during planned downtimes and guarantees zero data loss.
Planned Failover is used in the following cases
After turning off the primary virtual machine, PFO is performed on the primary virtual machine by right-clicking on the VM and choosing the Failover operation (either from the Hyper-V Manager or from the Failover Clustering Manager).
Please note – for the PFO to work from UI, remote WMI has to be enabled on the replica site and the user running the PFO should have the necessary privileges. More on remote WMI in a later blog.
PFO does the following
The above procedure can be achieved using Powershell using the following cmdlets.
Run these cmdlets on the primary side.
1: Stop-VM VirtualMachine_Workload
3: Start-VMFailover -VMName VirtualMachine_Workload –prepare
Run these cmdlets on the replica side.
1: Start-VMFailover -VMName VirtualMachine_Workload
3: Set-VMReplication -reverse -VMName VirtualMachine_Workload
5: Start-VM VirtualMachine_Workload
On a cluster, these cmdlets should be run against the node which is currently owning the virtual machine.
In the last part of this series, I will talk about Unplanned Failover and summarize the differences between these 3 failovers. Stay tuned!
Would love to see this integrated with Live Migration. I don't quite understand why the VM has to be shut down for a planned failover...
The primary VM needs to be shutdown to ensure that there is zero data loss when the replica VM comes up.
The scenario and requirements for Live Migration (LM) and Planned Failover (PFO) are different - while LM promises high-availability, PFO has been specifically built keeping disaster recovery & replication in mind.
To add to Praveen, Hyper-V Replica is primarily targeted for protection to a remote site over WAN. Given that the product has to work for all environments starting from low to high bandwidth - all over WAN - getting a failover to work in a "live" manner without downtime requires a lot of work to get it right. We prioritized that lower over other problems we were solving for this release.