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

Keyur Bhalerao <keyurbhalerao@xxxxxxxxx> · Tue, 5 Jan 2016 12:53:01 -0800

Hi ,
Based on the discussion and links referred as mentioned in earlier thread , I could able to perform the block commit and other operations successfully.  Here are the changes required to perform block commit 

1. Used Ubuntu 15.04 which has following versions of Libvirt and Qemu 

Compiled against library: libvirt 1.2.12
Using library: libvirt 1.2.12
Using API: QEMU 1.2.12
Running hypervisor: QEMU 2.2.0 

-- Need to mention here : The Qemu version 2.3 certainly has some issues regarding the block commit as lowering the version to 2.2 resolved "active block job" issue.

2. Modified the configuration /etc/libvirt/qemu.conf 
   - Had to modify the qemu.conf file which is under /etc/libvirt to resolve the permission denied error. 
   - Added  security_driver="none" 
Supportive reference  : https://libvirt.org/drvqemu.html 

I have two question regarding this.- 

1. Is there any way we can avoid modifying /etc/libvirt/qemu.conf  for security driver changes and perform block commit . ?
2. Has anyone tried with Qemu 2.4 for blockcommit and related operations ? Does it work ?  (I know this might not be relevant to libvirt users for sure it will help if someone trying block commit and related operations)

Thanks,
Keyur Bhalerao

On Tue, Dec 8, 2015 at 11:32 PM, Dominique Ramaekers <dominique.ramaekers@xxxxxxxxxx> wrote:

This is not a libvirt/redhat question…

With your method you can only revert to versions which are available in the standard repositories. You’ll have to download the packages manually
 to force a different version. Use with caution. There is a reason why the version isn’t in the standard repositories.

Van: libvirt-users-bounces@xxxxxxxxxx [mailto:libvirt-users-bounces@xxxxxxxxxx]
Namens Keyur Bhalerao

Verzonden: woensdag 9 december 2015 0:05

Aan: Kashyap Chamarthy

CC: libvirt-users@xxxxxxxxxx

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

Hi

Was trying to get specific qemu-kvm version. Do you know any way to get the 2.1.2 installed. Was trying sudo apt-get install qemu-kvm=1.2.1 but its not working. 

Tried with sudo apt-get install qemu-kvm tree=1.2.1

But both have failed for Version not found.

Thanks

Keyur

On Tue, Dec 8, 2015 at 11:21 AM, Keyur Bhalerao <keyurbhalerao@xxxxxxxxx> wrote:

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@xxxxxxxxxx> 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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