Re: [ovirt-users] Re: Any way to terminate stuck export task

[Nir Soffer]

On Sun, Jul 4, 2021 at 11:30 AM Strahil Nikolov <hunter86_bg@yahoo.com> wrote:
>
> Isn't it better to strace it before killing qemu-img .

It may be too late, but it may help to understand why this qemu-img
run got stuck.

> Best Regards,
> Strahil Nikolov
>
> On Sun, Jul 4, 2021 at 0:15, Nir Soffer
> <nsoffer@redhat.com> wrote:
> On Sat, Jul 3, 2021 at 3:46 PM Gianluca Cecchi
> <gianluca.cecchi@gmail.com> wrote:
> >
> > Hello,
> > in oVirt 4.3.10 an export job to export domain takes too long, probably due 
> > to the NFS server slow.
> > How can I stop in a clean way the task?
> > I see the exported file remains always at 4,5Gb of size.
> > Command vmstat on host with qemu-img process gives no throughput but 
> > blocked processes
> >
> > procs -----------memory---------- ---swap-- -----io---- -system-- 
> > ------cpu-----
> >  r  b  swpd  free  buff  cache  si  so    bi    bo  in  cs us sy id wa st
> >  1  2      0 170208752 474412 16985752    0    0  719    72 2948 5677  0  0 
> > 96  4  0
> >  0  2      0 170207184 474412 16985780    0    0  3580    99 5043 6790  0  
> > 0 96  4  0
> >  0  2      0 170208800 474412 16985804    0    0  1379    41 2332 5527  0  
> > 0 96  4  0
> >
> > and the generated file refreshes its timestamp but not the size
> >
> > # ll -a  
> > /rhev/data-center/mnt/172.16.1.137:_nas_EXPORT-DOMAIN/20433d5d-9d82-4079-9252-0e746ce54106/images/125ad0f8-2672-468f-86a0-115a7be287f0/
> > total 4675651
> > drwxr-xr-x.  2 vdsm kvm      1024 Jul  3 14:10 .
> > drwxr-xr-x. 12 vdsm kvm      1024 Jul  3 14:10 ..
> > -rw-rw----.  1 vdsm kvm 4787863552 Jul  3 14:33 
> > bb94ae66-e574-432b-bf68-7497bb3ca9e6
> > -rw-r--r--.  1 vdsm kvm        268 Jul  3 14:10 
> > bb94ae66-e574-432b-bf68-7497bb3ca9e6.meta
> >
> > # du -sh  
> > /rhev/data-center/mnt/172.16.1.137:_nas_EXPORT-DOMAIN/20433d5d-9d82-4079-9252-0e746ce54106/images/125ad0f8-2672-468f-86a0-115a7be287f0/
> > 4.5G    
> > /rhev/data-center/mnt/172.16.1.137:_nas_EXPORT-DOMAIN/20433d5d-9d82-4079-9252-0e746ce54106/images/125ad0f8-2672-468f-86a0-115a7be287f0/
> >
> > The VM has two disks, 35Gb and 300GB, not full but quite occupied.
> >
> > Can I simply kill the qemu-img processes on the chosen hypervisor (I 
> > suppose the SPM one)?
>
> Killing the qemu-img process is the only way to stop qemu-img. The system
> is designed to clean up properly after qemu-img terminates.
>
> If this capability is important to you, you can file RFE to allow aborting
> jobs from engine UI/API. This is already implemented internally, but we did
> not expose the capability.
>
> It would be useful to understand why qemu-img convert does not make progress.
> If you can reproduce this by running qemu-img from the shell, it can be useful
> to run it via strace and ask about this in qemu-block mailing list.
>
> Example strace usage:
>
>     strace -o convert.log -f -tt -T qemu-img convert ...
>
> Also output of nfsstat during the copy can help.
>
> Nir
>
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