Protecting a Virtual Machine and also inside a guest

1:18 pm in Uncategorized by mikeresseler

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.

The DPM BoothMe and Hypervbear courtesy by @hypervbear


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:

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
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.