[Qemu-devel] "File too large" error from "qemu-img snapshot" (was Re: AW: Bug Repoting Directions Request)

[Paolo Bonzini]

On 19/11/2014 12:39, Prof. Dr. Michael Schefczyk wrote:
> Dear Paolo,
> 
> thank you very much for your prompt reply.

Hi,

please keep the replies on the mailing list.  I've added the qemu-devel
mailing list, where more people should be able to see the message and
hopefully reply with something helpful.

Also, how do you do the backups?

Paolo

> For example, I have a guest named "gatewayb72.img" where the backup failed. 
> If I thereafter try to create or delete a snapshot, the following reply 
> occurs on the command line:
> 
> 
> address@hidden kvm02]# qemu-img snapshot -d gatewayb72 /kvm02/gatewayb72.img
> qemu-img: Could not open '/kvm02/gatewayb72.img': Could not read snapshots: 
> File too large
> 
> 
> If I want to reboot that machine, I get the following error:
> 
> 
> Fehler beim Starten der Domain: Interner Fehler: Prozess wurde während der 
> Verbindungsaufnahme zum Monitor beendet : qemu-kvm: -drive 
> file=/kvm02/gatewayb72.img,if=none,id=drive-virtio-disk0,format=qcow2,cache=none:
>  could not open disk image /kvm02/gatewayb72.img: Could not read snapshots: 
> File too large
> 
> 
> Traceback (most recent call last):
>   File "/usr/share/virt-manager/virtManager/asyncjob.py", line 100, in 
> cb_wrapper
>     callback(asyncjob, *args, **kwargs)
>   File "/usr/share/virt-manager/virtManager/asyncjob.py", line 122, in tmpcb
>     callback(*args, **kwargs)
>   File "/usr/share/virt-manager/virtManager/domain.py", line 1220, in startup
>     self._backend.create()
>   File "/usr/lib64/python2.7/site-packages/libvirt.py", line 698, in create
>     if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
> libvirtError: Interner Fehler: Prozess wurde während der Verbindungsaufnahme 
> zum Monitor beendet : qemu-kvm: -drive 
> file=/kvm02/gatewayb72.img,if=none,id=drive-virtio-disk0,format=qcow2,cache=none:
>  could not open disk image /kvm02/gatewayb72.img: Could not read snapshots: 
> File too large
> 
> 
> Based on the facts I can see, the file is not too large. When reading the 
> first error, the file size was 13.8 GB, while the limit is 14.5 GB. The same 
> does also happen with files which are only, for example 6 GB big, while their 
> limit is also 14.5 GB. Therefore, I think that the "file too large" really 
> stands for something else.
> 
> Can I provide any additional information?
> 
> Regards,
> 
> Michael
> ___________________________________________________________ 
> Technische Universität Dresden
> Fakultät Wirtschaftswissenschaften
> Lehrstuhl für Entrepreneurship und Innovation
> Prof. Dr. Michael Schefczyk
> D-01062 Dresden 
>  
> Fon: +49-3 51-4 63-3 68 81 
> Fax: +49-3 51-4 63-3 68 83 
> www.gruenderlehrstuhl.de

>> Since some months ago, I am facing the problem, that backups fail 
>> unpredictably. A failed backup does not generate a backup file and 
>> thereafter, snapshots can no longer be created or deleted and the 
>> guest cannot be started anymore. The resulting error message is "File 
>> too large".
> 
> Who is reporting the "File too large" error?  Can you please include the 
> error in full detail?
> 
> Paolo
>