No way to exclude disks

[rickyketch]

An interesting project. I tried virtnbdbackup on a CentOS 7 VM on a Fedora 33 host. The VM has a small, QCOW2 system disk and a large, raw storage disk, and a CDROM drive that is unused, but it got created by default. I only wanted to back up the system disk, vda.

At first it couldn't get past the CDROM drive, sda:
ERROR:root:unsupported configuration: disk 'sda' has no media
I attached an iso file to the CDROM drive and then got:
ERROR:root:unsupported configuration: disk 'sda' is empty or readonly
So I deleted the CDROM drive and then it couldn't get past the raw storage drive, vdb
ERROR:root:unsupported configuration: checkpoint for disk vdb unsupported for storage type raw
So I deleted the vdb disk device, and only then it succeeded in creating a backup of the system disk, vda.

I found in the code the "--include" commandline switch:
parser.add_argument("-i", "--include", default=None, type=str, help="Backup only disk with target dev name specified")
That seems like just what I needed.
[root@oplx7010 2TBpart]# virtnbdbackup -d centos7.0 -i vda -l full -o centos7.0.virtnbdbackup

But I still failed the same way with the same messages. The "include" switch had no apparent effect. It did not result in the other disks being ignored as I would have expected.

Thank you.
Richard Ketcham

[abbbi]

its some time since ive used it as i currently have no test setup. The include swich should work as expeced, does "vda" match the virtual disks target name in the xml configuration? According to the source, im checking for the target name:

      for disk in disks:                                                                                                                                                     
      ┆   if args.include != None and disk.diskTarget != args.include:                                              
      ┆   ┆   logging.info("Skipping disk: %s" % disk.diskTarget)                              
      ┆   ┆   continue  

one would need the vm XML configuration to check why it doesnt skip the disks.

[rickyketch]

abbbi, I believe "vda" does match

<devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/home/virt/DRBL-C7.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
    </disk>
    <disk type='file' device='disk' snapshot='no'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/2TBpart/IMGSTOR-B.img'/>
      <target dev='vdb' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x0a' slot='0x00' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='sda' bus='sata'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>

DRBL-C7.xml.TXT

[abbbi]

can you post complete output of your command? Does the "Skipping disk:" logline appear at all?
disk.diskTarget should be "vda" in you case and it should match.

[rickyketch]

[root@oplx7010 virt]# virtnbdbackup -d DRBL-C7 -l full -o backup -i vda ERROR:root:Domain is missing required incremental-backup capability.

the domain configuration iss missing the required incremental flag like described in the README:

https://github.com/abbbi/virtnbdbackup#prerequisites

[abbbi]

Can you try the version in branch issue2,it should now automatically exclude cdrom and raw devices.
efc0cc3

[abbbi]

[root@oplx7010 virt]# virtnbdbackup -d DRBL-C7 -l full -o backup -i vda ERROR:root:Domain is missing required incremental-backup capability.

the domain configuration iss missing the required incremental flag like described in the README:

https://github.com/abbbi/virtnbdbackup#prerequisites

[rickyketch]

Ok, I just created a new, plain vanilla, centos7.0 VM to try to replicate the problem and I still got that last error message.

[root@oplx7010 virt]# virtnbdbackup -d centos7.0 -l full -o backup -i vda ERROR:root:Domain is missing required incremental-backup capability.

Then I remembered, I forgot to add "<qemu:add capability='incremental-backup'/>" like I did before.
Well, now I can't:

[root@oplx7010 virt]# virsh edit centos7.0 error: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng Element domain has extra content: qemu:capabilities

and I'm trying to figure out why I could before and now I can't. Something new I've noticed with Fedora 33 is that it automatically installs updates every time I reboot. And I see that schema file got updated just a few days ago:

[root@oplx7010 qemu]# rpm -q --last libvirt-libs-6.6.0-5.fc33.x86_64 libvirt-libs-6.6.0-5.fc33.x86_64 Thu 18 Mar 2021 04:38:08 PM PDT

[abbbi]

[root@oplx7010 virt]# virtnbdbackup -d centos7.0 -l full -o backup -i vda ERROR:root:Domain is missing required incremental-backup capability.

Then I remembered, I forgot to add "<qemu:add capability='incremental-backup'/>" like I did before.
Well, now I can't:
[root@oplx7010 qemu]# rpm -q --last libvirt-libs-6.6.0-5.fc33.x86_64 libvirt-libs-6.6.0-5.fc33.x86_64 Thu 18 Mar 2021 04:38:08 PM PDT

hm.. not sure, but maybe things have changed now with more recent libvirt versions, it seems to be enabled by
default now:

https://bugzilla.redhat.com/show_bug.cgi?id=1799015

[abbbi]

hi,

i tried on centos8 with the latest advanced virtualization stream and i still need to add the XML definition,
system comes with libvirt 6.6.0 aswell. (6.6.0-13). you need to be sure that the FIRST line of the virtual machine is:

<domain type='kvm' id='4' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>

so the schema applies!

[abbbi]

hi again,

i have a new test setup and was able to fix a few things in the current master branch:

1. cdrom and unsupported devices are now ignored during checkpoint creation,
   in case virtual disk does not support checkpointing, an warning is issued, see issue Ignore CDROM / Direct attached block devices #3

2. the include option works just right for me, using the following command:

./virtnbdbackup -d debian10 -l full -i vdb -o blax

i see only vdb is backed up:

INFO:root:Skipping disk: vda

Anyway, try the latest master version, it should fix your issues.

[rickyketch]

Yes indeed. All is working now. Thank you!