Protecting a Virtual Machine and also inside a guest
Working on the Microsoft System Center Data Protection Manager booth the last few days got myself quite some insight in what customers want from DPM. It also brought up a few “issues” that actually are non-issues but where you need to do a few steps to get the issue out of the way.
This is the scenario. People want to protect the entire virtual machine once a day, a week, a … depending on their needs. At the same time, they want to add a DPM agent inside the guest to enjoy the “every 15 minutes backup” for SQL or Exchange or so.
This scenario provides two great things:
1. You have a Disaster Recovery plan
You can recover your entire virtual machine, from x-days old. Start the box, and then recover the latest data in the guest
2. You have a restore test scenario
Recover the virtual machine to an alternate hyper-v host. And then do the recovery inside the guest again.
So you get real value for this scenario. But here’s the catch. When you are protecting the hyper-v machine, it will also go inside the guest to get a consistent state and truncate logs. But you have also a guest backup that also will truncate logs… Houston, we have a problem here…
Luckily there is an answer to this problem.
The issue is described in this KB article:
http://support.microsoft.com/kb/975354
Issue 3
The application backup operation in the virtual machine (VM) is incorrectly affected by the VM backup operation on the server that is running Hyper-V.
However, in some cases, this doesn’t solve the problem. Don’t panic… Here is what you need to do:
You can apply the following registry entry in a virtual machine to fix "Issue 3" for that virtual machine:
Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Virtualization\VssRequestor
Name: BackupType
Type: REG_DWORD
Value: 0 or 1
If this registry entry is created and its value is set to 1 , application backup will not be affected by the virtual machine backup operation on the server that is running Hyper-V. If this registry entry does not exist, or if its value is 0 , the "Issue 3" occurs.
Enjoy
Mike