On Mon, Apr 27, 2020 at 10:13:37 +0200, Paul van der Vlis wrote:
Op 27-04-2020 om 09:02 schreef Peter Krempa:
On Sat, Apr 25, 2020 at 16:40:35 +0200, Paul van der Vlis wrote:
Op 25-04-2020 om 16:00 schreef Paul van der Vlis:
Hello,
I have a qcow2 disk what needs to become increased.
I don't have space on the location where it is now to have it two time, so I want to live-migrate it to another host.
On the other host I have to create a qcow2 disk before I can migrate.
What would happen when I would create there a bigger qcow2 disk then the original one? Can I resize the filesystem after the migration?
Not sure why, but I thought it's not possible to encrease qcow2 disks without copying the disk. But now I find many manuals what say it's no problem. Sorry...
It definitely is possible. There are multiple options though and I didn't quite get which one is your case:
1) QCOW2 image is too small but theres unused space on the filesystem where the image is stored:
- live: The image can be resized live via 'virsh blockresize'. You then must modify the partitions and enlarge filesystem.
Interesting, that would be better then what I did now.
- offline: 'virt-resize' tool from the libguestfs package can be used to do it offline and it should be able to resize your partitions and filesystem as well.
What I did is this:
virsh shutdown kvm68 qemu-img resize /data/kvm68.qcow2 +800G virsh start kvm68 ssh root@kvm68.vandervlis.nl lsblk pvs apt install cloud-guest-utils growpart /dev/vda 1 pvresize /dev/vda1 lsblk lvextend -rL +100G /dev/vg0/root
2) QCOW2 is too small and there isn't enough space on the filesystem, but there's enough space on a different filesystem on the same host:
- live: 'virsh blockcopy' can be used to copy the existing image to the new filesystem while the VM is running and then switch to it. You can then use same steps as in 1) to resize the filesystem.
I did not know this command. Thanks. Could be usefull.
- offline copying the image and using the steps from 1) is the best bet here
3) QCOW2 is too small and there isn't enough storage on the same host, but there is a different host where I want to run it.
-live You can use VM live migration to migrate the VM to the other host and then enlarge the disk using steps in 1). Please refer to the docs of live migration.
I use normally something like this, because in my case every fysical server has it's own storage:
virsh migrate --live --p2p --copy-storage-inc --persistent \ --undefinesource --verbose $vm qemu+ssh://$other/system
A point is that I have to create disk(s) on the other side with qemu-img, I did not found a way to do that automatically. My question
We are able to pre-create the storage given that a full copy is requested (copy-storage-all, not copy-storage-inc) and the images reside in a location covered by a libvirt 'directory' storage pool at least on the destination of the migration. Unfortunately we can't do it for incremental at this point.
was what would happen when I would create a bigger disk there then the original one.
I'm not sure now whether the new size will be picked up, but nothing should break, so you can give it a try. Certainly a shutdown and start of the VM will fix it if it's not picked up or a blockresize.