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Best way to copy VM while it is live?

Posted: 2018/06/13 17:07:32
by valkaben
Hello, I'd like to backup my CentOS6 KVM at work which is our DNS and DHCP server. If it turns off, we'll have a bit of chaos at work so I don't want to turn it off. I would like to back up the virtual machine image though. I was considering snapshotting it but I did notice snapshot freezes the virtual machines and temporarily makes it inactive. I can't have that happen.

I know of LVM snapshots but the previous sysadmin did not leave any room in the volume group so I am unable to do that. Any other tips to back up a live running VM?

Re: Best way to copy VM while it is live?

Posted: 2018/06/14 03:26:02
by Whoever
Some ideas:
1. Add a hard drive and extend the volume group so that there is room for an LVM snapshot. LVM snapshots don't require much space.
2. If the image is a qemu image, then you can snapshot it directly.
3. I haven't tried this, but, assuming you have disk space in a filesystem, you might be able to create a large file, set up a loopback device that points to the points to the file, then add the loopback device to your volume group, to extend it sufficiently to hold a snapshot for a short time.