Confusion on method of backing up live/in use virtual machines
Hello,
There is some confusion here over how we should backup our virtual machines. Let me provide the environment first.
1. Physical host machines are Dell Servers.
2. Virtual Product: VMWare Workstation 8 - So visualization on top of windows.
3. We have several Virtual Machines that startup when the host machines boot. Since we have two physical servers, we have two virtual Windows 2008 Domain Controllers (One on each physical server) and Antivirus Manager VM and OpsView virtual machines.
4. The confusion is this: Should we install the Acronis Backup Agent within each virtual machine and setup their backup schedules to backup to the physical hosts machine folder repository
5. OR should the Physical Host use its Acronis program to backup the older which contains the LIVE virtual machines in use?
Concerns:
We are afraid that live, running virtual machines, will get corrupted if they are restored back into the folder. We fully understand that you cannot restore a LIVE running VM but if restored the VM would think that it merely had a non graceful shutdown, as say in a power failure situation or abrupt shutdown due to an environment issue.
Why would we want to backup live running VM's?
Our VM hard drives are configured in a way that uses smaller files. This is due to the problem we faced a long time ago when a very large VM had a 85gig drive single file. Moving that took 6 hours. We later created a 90gig partition but used the smaller (2 gig) files, a feature that is stated within VMWare Workstation. While this created about 50, two gig files, moving them took about 1 hour, a huge savings in time.
Restoring a live VM at the host level would retain the correct file structure of the VM within the folder.
Restoring a VM that used an Agent inside the VM would restore one very large .vmdk file which we would assume would take a very long time and defeat our preferred smaller file VM method.
Hope this makes sense and thanks for any guidance ahead of time.
I'd install agents inside VM. With file backup of of VM's files on host it may happen that all files of VM that are held open while VM is running will be included in the incremental copy, no matter whether they were modified or not, and will have the same size as full one. Also, it will back up 'dirty' sectors that were once used but now are not, however are still stored in .vmdk file. You can overcome the problem with recreating of 2 gig files if you create virtual machine manually with desired configuration and restore onto it from bootable media, instead of 'converting' the backup to virtual machine. However installing agents inside VMs may require more licenses.
I just tested this on a running VM that was backed up and not critical. So I basically backed up the running VM's folder.
Restoration was a snap, no issues, it backed up even the locked files (As I enabled VSS on the Acronis Backup).
The VM was an XP machine too which doesn't always jive with visualization.
So I am not sure if I was lucky or this is a legit method. I hope someone from Acronis will chime in and state whether either method is valid or not.
Thanks.
As I enabled VSS on the Acronis Backup
If this is true, http://communities.vmware.com/message/1876632 , vmware Workstation has no VSS writer, so doesn't matter. It's just like a regular snapshot. Another thing that probably matters is that while crash-consistent state from within VM NTFS journaling ensures all this NTFS metadata integrity, the same from ( yes it does - on windows - http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cm… - On Windows hosts, VMware hosted products use unbuffered IO by default. ) . To be sure, you can probably use steps 1 and 7 from the first link as pre-post commands.
Great find and very interesting. So looks like, to be safe, that I should use the Acronis Backup Agent from within the VM even though my test worked. it worked due to the Windows unbuffering, but I do have Linux VM Appliances as well, which could be damaged due to the buffering.
Well that answers that, thanks again for the post and help!
but I do have Linux VM Appliances as well, which could be damaged due to the buffering.
No, it's the host OS that matters. So you will be ok.
I see, I misread and thought it was the VM OS that mattered, not the Host hosting the VM's.
Great, this will make my recovery far easier. I will continue testing the backups and recovery. Appreciate all the help folks.