virtualbox.org

Hi,

I'm trying to provide advice to someone I know that is looking to get started with VirtualBox, but I'm having difficulty finding a backup solution that I feel is adequate. I'm wondering if anyone knows of existing backup software, open source or commercial, that can be used to backup virtual machines using the following strategy:

• Perform an ACPI shutdown of the guest.
• Take a snapshot of the current state...
• -- VirtualBox's built in snapshots are preferable.
• -- Windows VSS or Linux LVM may be an option if there are major advantages.
• Start the guest.
• Copy or sync the non-changing VDI / snapshots to a backup destination.
• -- USB disk if the backup sets are very large.
• -- Offsite over the network if possible.

It's a relatively small organization. They'll only be running about half a dozen VMs and can tolerate several minutes of downtime per VM per night for backups. They're working with a relatively small budget, but commercial software is an option if that's what's necessary to get a decent backup strategy in place.

The reason VirtualBox's built in snapshots are preferable to VSS or LVM is due to the resources that would be available for fail over. They don't have the resources to set up a dedicated fail over system and would likely use one or two re-purposed Windows 7 PCs if their main machine failed. AFAIK it isn't possible to script snapshot creation via VSS using Windows 7 and having a backup system that would keep working on a re-purposed Windows 7 machine would be preferable. They are more comfortable dealing with Windows than Linux.

I have two questions:

1. When I shut down a guest OS and take a (VirtualBox) snapshot, are the VDI and all previous snapshot files read only after I restart the VM? I've tested this and it seems to be the case, but I'd like to make sure I'm not overlooking anything.

2. Ignoring the complexities of discarding the most recent snapshot file when restoring, are there any challenges created by using VirtualBox's built in snapshots instead of VSS or LVM?

I'd welcome any other thoughts / tips.

You dont need special software to back up the VM, just use the host to copy the VM folder to external storage.

And don't make the noob mistake of thinking that snapshots are in any way useful as backups. They certainly are not.

mpack wrote:And don't make the noob mistake of thinking that snapshots are in any way useful as backups. They certainly are not.

I thought they could be useful for getting things into a consistent state with minimal downtime. Consider doing the following on a VM with no snapshots:

• Cleanly shut down the guest OS and wait for the VM to power off.
• Take a snapshot of the VM.
• Start the VM.

At that point, shouldn't the VDI (disk) be in read-only mode? I assume backing up the VDI at that point and ignoring the snapshot file would give me a consistent backup for the point in time where the VM was powered off. Is that wrong? I know the .vbox configuration file would need to be modified manually to discard the snapshot. That wouldn't be the type of task you'd want to deal with when recovering from backup which is why I was thinking someone may have written software for the task.

Even if the above is correct, maybe it's a bad complexity vs downtime trade-off. It adds a lot of complexity and only saves a few minutes of downtime compared to leaving the VM powered off while (locally) copying the entire VM directory to a staging area. If those few extra minutes of downtime aren't tolerable, would VSS or LVM snapshots be preferable to VirtualBox's built in snapshots if the goal is to create a backup for the point in time where the VM was powered down?

That procedure would allow you to back up the base VDI, which is not the same as a backup of the VM.