Re: Read-only iscsi disk? Or hot-plug?
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.