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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