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Keyur Bhalerao

2015-Dec-07 20:52 UTC

[libvirt-users] Efficient live disk backup with active blockcommit : Failed 'block-commit': Could not reopen file: Permission denied

Hi ,

Working on the simple POC : Advanced snapshot using libvirt and qemu .
Following are the exact steps which are followed .

1. Created as base VM - Ubuntu 15.10 with following libvirt and qemu
versions
   Using library: libvirt 1.2.16
   Using API: QEMU 1.2.16
   Running hypervisor: QEMU 2.3.0

   QEMU emulator version 2.3.0 (Debian 1:2.3+dfsg-5ubuntu9.1), Copyright
(c) 2003-2008 Fabrice
   Bellard

2.Created nested VM (vm-01) using VirtManager on base VM.
3.Used following commands to take the multiple snapshots -

virsh # list
 Id    Name                           State
----------------------------------------------------
 7     vm-01                          running

virsh # domblklist vm-01
Target     Source
------------------------------------------------
vda        /home/ubuntu/vm-01.img
hda        /dev/sr0

snapshot-create-as --domain vm-01 snap1 --diskspec
vda,file=/var/lib/libvirt/sn1.qcow2 --disk-only --atomic
snapshot-create-as --domain vm-01 snap2 --diskspec
vda,file=/var/lib/libvirt/sn2.qcow2 --disk-only --atomic

virsh #snapshot-list vm-01

------------------------------------------------------------
 snap1                2015-12-07 11:51:51 -0800 disk-snapshot
 snap2                2015-12-07 11:52:28 -0800 disk-snapshot

virsh # snapshot-list vm-01 --tree
snap1
  |
  +- snap2

List the current block device in use, again. It can be noticed, the new
overlay 'sn2.qcow2' is the current disk in use:

virsh # domblklist vm-01

Target     Source
------------------------------------------------
vda        /var/lib/libvirt/sn2.qcow2
hda        /dev/sr0

Now that the backup is finished, perform active blockcommit by live
mergning contents of sn2 into base:

ubuntu@keyurubuntu:~$ virsh blockcommit vm-01 vda --active --verbose --pivot
error: internal error: unable to execute QEMU command 'block-commit':
Could
not reopen file: Permission denied

I am not sure why this is getting as permission denied. I have tried couple
of times reinstalling and creating new VMs . Every time when i have tried
to block-commit getting landed into  same error.

Is there any troubleshooting or solution to this issue. Stuck on this issue
for last 2 days.
Quick help much appreciated.

Thanks,
Keyur Bhalerao

Reference used -
http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
                        -
http://kashyapc.com/2012/09/14/externaland-live-snapshots-with-libvirt/

Dominique Ramaekers

2015-Dec-08 07:58 UTC

head link

Re: [libvirt-users] Efficient live disk backup with active blockcommit : Failed 'block-commit': Could not reopen file: Permission denied

I had similar issues on Ubuntu 15.10. I’ve downgraded Qemu to 2.1. Now it works
like a charm.


Van: libvirt-users-bounces@redhat.com [mailto:libvirt-users-bounces@redhat.com]
Namens Keyur Bhalerao
Verzonden: maandag 7 december 2015 21:53
Aan: libvirt-users@redhat.com
Onderwerp: [libvirt-users] Efficient live disk backup with active blockcommit :
Failed 'block-commit': Could not reopen file: Permission denied

Hi ,

Working on the simple POC : Advanced snapshot using libvirt and qemu . Following
are the exact steps which are followed .

1. Created as base VM - Ubuntu 15.10 with following libvirt and qemu versions
   Using library: libvirt 1.2.16
   Using API: QEMU 1.2.16
   Running hypervisor: QEMU 2.3.0

   QEMU emulator version 2.3.0 (Debian 1:2.3+dfsg-5ubuntu9.1), Copyright (c)
2003-2008 Fabrice
   Bellard

2.Created nested VM (vm-01) using VirtManager on base VM.
3.Used following commands to take the multiple snapshots -

virsh # list
 Id    Name                           State
----------------------------------------------------
 7     vm-01                          running

virsh # domblklist vm-01
Target     Source
------------------------------------------------
vda        /home/ubuntu/vm-01.img
hda        /dev/sr0

snapshot-create-as --domain vm-01 snap1 --diskspec
vda,file=/var/lib/libvirt/sn1.qcow2 --disk-only --atomic
snapshot-create-as --domain vm-01 snap2 --diskspec
vda,file=/var/lib/libvirt/sn2.qcow2 --disk-only --atomic

virsh #snapshot-list vm-01

------------------------------------------------------------
 snap1                2015-12-07 11:51:51 -0800 disk-snapshot
 snap2                2015-12-07 11:52:28 -0800 disk-snapshot

virsh # snapshot-list vm-01 --tree
snap1
  |
  +- snap2

List the current block device in use, again. It can be noticed, the new overlay
'sn2.qcow2' is the current disk in use:

virsh # domblklist vm-01

Target     Source
------------------------------------------------
vda        /var/lib/libvirt/sn2.qcow2
hda        /dev/sr0

Now that the backup is finished, perform active blockcommit by live mergning
contents of sn2 into base:

ubuntu@keyurubuntu:~$ virsh blockcommit vm-01 vda --active --verbose --pivot
error: internal error: unable to execute QEMU command 'block-commit':
Could not reopen file: Permission denied

I am not sure why this is getting as permission denied. I have tried couple of
times reinstalling and creating new VMs . Every time when i have tried to
block-commit getting landed into  same error.

Is there any troubleshooting or solution to this issue. Stuck on this issue for
last 2 days.
Quick help much appreciated.

Thanks,
Keyur Bhalerao

Reference used -
http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
                        -
http://kashyapc.com/2012/09/14/externaland-live-snapshots-with-libvirt/

Kashyap Chamarthy

2015-Dec-08 13:18 UTC

head link

Re: [libvirt-users] Efficient live disk backup with active blockcommit : Failed 'block-commit': Could not reopen file: Permission denied

On Mon, Dec 07, 2015 at 12:52:34PM -0800, Keyur Bhalerao wrote:

[. . .]

 ubuntu@keyurubuntu:~$ virsh blockcommit vm-01 vda --active --verbose
--pivot> error: internal error: unable to execute QEMU command
'block-commit': Could
> not reopen file: Permission denied
Fairly obvious suggestions, ensure permissions are set so that QEMU has
permissions to the dir that contains images.

Or it could be an AppArmor issue.

Also, check your logs:

    /var/log/libvirt/qemu/$VM.log
    /var/log/libvirt/libvirtd.log  (assuming you have debug logging
    enabled)
> I am not sure why this is getting as permission denied. I have tried
> couple of times reinstalling and creating new VMs . Every time when i
> have tried to block-commit getting landed into  same error.
> 
> Is there any troubleshooting or solution to this issue. Stuck on this
> issue for last 2 days.  Quick help much appreciated.
> 
> Thanks, Keyur Bhalerao
> 
> Reference used -
> http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
> -
> http://kashyapc.com/2012/09/14/externaland-live-snapshots-with-libvirt/
-- 
/kashyap

Keyur Bhalerao

2015-Dec-08 19:21 UTC

head link

Re: [libvirt-users] Efficient live disk backup with active blockcommit : Failed 'block-commit': Could not reopen file: Permission denied

Thanks Kashyap for replying.

QEMU has permissions to the directory which is having images. I will look
into the AppArmor issue and find out more about this.
Also as per suggestion from the link i have uncommented the user and group
from the qemu.conf file - https://github.com/jedi4ever/veewee/issues/996

By checking more on the AppArmor and sVirt issue  , i have modified the
qemu.conf for security_driver="none". The result for this is no
permission
error but another error which can be related to QEMU 2.3.0

virsh # blockcommit vm-01 vda --verbose --pivot --active
Block Commit: [100 %]error: failed to pivot job for disk vda
error: internal error: unable to execute QEMU command
'block-job-complete':
The active block job for device 'drive-virtio-disk0' cannot be completed

Searched more for this type of error and found -

https://bugs.launchpad.net/qemu/+bug/1455475

Looks like bug in QEMU 2.3.0 . Checking now with QEMU 2.1 for the same.

Let me know if anything to more look for.




Thanks,
Keyur Bhalerao


On Tue, Dec 8, 2015 at 5:18 AM, Kashyap Chamarthy <kchamart@redhat.com>
wrote:
> On Mon, Dec 07, 2015 at 12:52:34PM -0800, Keyur Bhalerao wrote:
>
> [. . .]
>
>  ubuntu@keyurubuntu:~$ virsh blockcommit vm-01 vda --active --verbose
> --pivot
> > error: internal error: unable to execute QEMU command
'block-commit':
> Could
> > not reopen file: Permission denied
>
> Fairly obvious suggestions, ensure permissions are set so that QEMU has
> permissions to the dir that contains images.
>
> Or it could be an AppArmor issue.
>
> Also, check your logs:
>
>     /var/log/libvirt/qemu/$VM.log
>     /var/log/libvirt/libvirtd.log  (assuming you have debug logging
>     enabled)
>
> > I am not sure why this is getting as permission denied. I have tried
> > couple of times reinstalling and creating new VMs . Every time when i
> > have tried to block-commit getting landed into  same error.
> >
> > Is there any troubleshooting or solution to this issue. Stuck on this
> > issue for last 2 days.  Quick help much appreciated.
> >
> > Thanks, Keyur Bhalerao
> >
> > Reference used -
> > http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
> > -
> >
http://kashyapc.com/2012/09/14/externaland-live-snapshots-with-libvirt/
>
> --
> /kashyap
>

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