How to live-resize guest (non-root) drive?

[nicorac]

Hello everyone,
I'm setting up a Linux File Server VM with ProxmoxVE.

Since Samba doesn't allow to set up quota for a share, my VM config is like the following.
Everything is (obviously) over LVM on the host.

root disk (will never change it)

virtio0: /dev/mapper/vm_root

and one (or more) additional drives, one for each share:

virtio1: /dev/mapper/vm_share1
virtio2: /dev/mapper/vm_share2
...

Well, it works well because users accessing \\srv\share1 are limited by the partition size itself.

Here comes the question: suppose vm_share1 was 10Gb and now I need it to grow to 20Gb.
I'll grow it with LVM and lvdisplay on the host confirms the new size.

Is there a way to tell the guest that now virtio1: is 20Gb without rebooting it?
I tried partprobe on the host with no success; I also tried to unbind the pci device (on the host) with

echo "0000:xx:xx.x" > /sys/bus/pci/drivers/virt_io/unbind

and bind it back again, no success.

I think that I should tell KVM to re-read this device properties, but I don't know how.

Can someone shed some light on it?
Thanks in advance.

 

[udo]

Hi,
i'm wonder that you don't use the normal disk-assigning with lvm-storage!

Have you tried "kpartx" inside the VM?

Udo

 

[nicorac]

You're right, I could define a single 100Gb disk on the host and attach it to the guest and manage it with LVM.
But I'd like to avoid the double LVM layer, one on the host and another one inside the guest.

That's why I defined my share disks in the host, then I attached all of them to the guest.

I'd like to resize them without rebooting; obviously I could accept a break on the single share I'm growing.