Ever since Hyper-V replication technology introduced in Windows 2012, many customers showed interest in leveraging DPM for backing up replica VMs instead of primary VMs. By backing up replica VMs, production servers are not burdened with the backup IO impact. Considering the customer request, DPM and Hyper-V replication worked together to enable backup of Replica VMs. The technology to make this happen and its nuances are further discussed in this Hyper-V Replica blog article. On the whole, it includes the changes to the platform that ensure crash-consistency of backups, and the appropriate retry mechanism in DPM to ensure a high success rate.
Testing and Results
The backup of Replica VMs by DPM has been validated with internal tests involving 2 servers with different VM mixes that are backed up by a DPM server(below).
We measured the actual number of backup points created per VM in DPM, and matched that with our expectation of 16 recovery points per VM for the 48 hour test duration. The results of the test were extremely positive, with close to 100% success rate of the backup jobs.
DPM Support Matrix
Here is the DPM VM protection support matrix with Hyper-V replication enabled deployments.
- DPM can backup replica VMs.
- DPM protection of a replica VM can guarantee only crash-consistency.