Can you rely on live backups of Exchange and SQL VMs?
One of the engineers from our storage team asked me to join a discussion about whether or not restoring VMs from images made by any of the live VM backup utilities would be a reliable process for a client. I unknowingly joined what was really a battle about whether the client would be better off using SAN based snapshots, host based replication, or live VM imaging specifically for Exchange and SQL VMs. All are proven solutions, and depending on budget, recovery objectives, and service level agreements all solutions could be deployed with confidence. The customer, and this post, is focused on the live VM backup solutions and their reliability for Exchange and SQL. Based on cost of implementation and infrastructure required the VM backup tools are the most affordable and easiest to deploy, but they also leave you with the most uncertainty.
Before continuing I want to point out that normal backup agents still need to be used for Exchange and SQL VMs. Not one of the VM backup solutions can perform application maintenance or specialized backups, like the Exchange Information Store backup for example. Understand that the live VM backup tools only specialize in capturing a quiescent, working image of the VM operating system and application.
First let’s understand what we mean when we say quiescent data. In the latest VMware Virtual Machine Backup Guide quiescing is defined as:
