Read-only iscsi disk? Or hot-plug?
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? 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. With regards, Paul -- Paul van der Vlis Linux systeembeheer Groningen https://www.vandervlis.nl/
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.
Op 07-09-2020 om 10:35 schreef Peter Krempa:
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.
Thanks, this did work! With regards, Paul
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.
-- Paul van der Vlis Linux systeembeheer Groningen https://www.vandervlis.nl/
participants (2)
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Paul van der Vlis -
Peter Krempa