virtualbox.org

I understand from this post viewtopic.php?p=29277#p29277 that I want to backup the entire virtualbox directory (which contains multiple virtual machines), of course while all the guests are closed. As the size of the base disks are very large and I want to make backups over time, what are recommended linux options?
Ideally it would be able to make differential backups based on changed sectors and not changed, files, but I do not know of any software that does this. Eg, rsync looks at changed files. So presumably if I was doing mirroring, it would re-backup every 40+ GB virtual machine every time, instead of just the changes.
What do other ppl use?

To backup VM images efficiently, create snapshots and then do an incremental backup. When you create a snapshot it baselines the original image and any previous snapshots. The image files before the snapshot no longer change and remain static. All new changes are only made on the new snapshot files. On a periodic bases (weekly) delete/roll-up all the snapshots and repeat. My book goes through the specifics in more detail. But you are free to just look at the backup scripts on my website (link in signature) and you don't have to buy the book! The backup scripts are numbered in the 400-series. An added advantage is to be able to restore back to the snapshot if something goes wrong (without even having to restore from backup). Also, you don't have to shutdown the VMs when doing snapshot. I have a supplementary check in the scripts to make sure the VM is not too busy before taking a live snapshot just to be safe.

Why so much about snapshots today? I thought people were finally getting the idea that they're evil. The last thing you need is to involve snapshots in your backup regime.

Nor is it necessary IME to back up the entire VirtualBoxVMs folder. Just back up selected VMs that are important to you. In general, choose a backup frequency that suits each VM. But, if you find it simpler to (say) copy the entire VirtualBoxVMs folder to a NAS then yes, I can see the argument for that.

mpack wrote:Why so much about snapshots today? I thought people were finally getting the idea that they're evil. The last thing you need is to involve snapshots in your backup regime.

Nor is it necessary IME to back up the entire VirtualBoxVMs folder. Just back up selected VMs that are important to you. In general, choose a backup frequency that suits each VM. But, if you find it simpler to (say) copy the entire VirtualBoxVMs folder to a NAS then yes, I can see the argument for that.

But if I don't use snapshots for backup purposes, isn't the backup incredibly wasteful because of all of the duplicated effort for a changed base disk file? I guess the alternative would be to infrequently backup the base disk and do a separate backup of the important files in the virtual machine.

I have been using the snapshot / backup regiment for over 5 years now over different versions of VirtualBox and it works like a charm. I have done extensive testing before using them by doing live snapshots while stressing out the VM and it has never failed. If you are not taking advantage of snapshots you are missing out in my opinion. Not to mention the times when it has saved me and I was able to go back to my 3 am snapshot a few times. I run 15 Virtual Machines and they all get snapshotted daily and backuped up daily. No issues whatsoever.

wvvls wrote:But if I don't use snapshots for backup purposes, isn't the backup incredibly wasteful

"Wasteful" is wonderful in a backup. That means it contains lots of redundancy and you can recover from almost anything. Well worth the cost of a big backup drive and a little extra time. I'm assuming that the backup is kept on another drive at least.