On Wed, Apr 22, 2020 at 07:51:09AM +0200, Anders Östling wrote: > I am fighting to understand the difference between backing up a VM by > using a regular copy vs using the virsh blockcopy command. > What I want to do is to suspend the vm, copy the XML and .QCOW2 files > and then resume the vm again. What are your thoughts? What are the > drawbacks compared to other methods?
Hi Anders, The k...@vger.kernel.org mailing list is mostly for the discussion and development of the KVM kernel module so you may not get replies. I have CCed libvir-list and developers who have been involved in libvirt backup features. A naive cp(1) command will be very slow because the entire disk image is copied to a new file. The fastest solution with cp(1) is the --reflink flag which basically takes a snapshot of the file and shares the disk blocks (only available when the host file system supports it and not available across mounts). Libvirt's backup commands are more powerful. They can do things like copy out a point-in-time snapshot of the disk while the guest is running. They also support incremental backup so you don't need to store a full copy of the disk image each time you take a backup. I hope others will join the discussion and give examples of some of the available features. Stefan
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