On Mon, Sep 07, 2020 at 10:07:29 +0200, Paul van der Vlis wrote: > Hello, > > I have an iSCSI disk with a backup. I want to use that backup on another > machine to test putting back data. > > What I use now is this: > ---- > <disk type='block' device='disk'> > <driver name='qemu' type='raw' cache='directsync' io='native'/> > <source dev='/dev/disk/by-id/scsi-36e843b6afdddf65dc4e9d4dc2dab66de'/> > <target dev='vdh' bus='virtio'/> > <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' > function='0x0'/> > </disk> > ---- > > Is it possible to do this read-only? Yes, you can add a <readonly/> element under disk to make it read only. You'll also need to use <shareable/> on the VM where it's read-write so that both VMs can access it.

Note that, if the VM in read-mode is actively writing to the device, the read-only VM may not know about that and may have the data changed while reading. > What I also could do is to hot-unplug the disk at the production > machine, and then hot-plug it at the test-machine. But the machines are > Windows, and I don't know Windows well. Windows should support unplug of the virtio device, so this should work as well.