[Gluster-users] [ovirt-users] slow performance with export storage on glusterfs

[Sahina Bose]

On Thu, Nov 23, 2017 at 4:56 PM, Jiří Sléžka <jiri.slezka at slu.cz> wrote:

> Hi,
>
> On 11/22/2017 07:30 PM, Nir Soffer wrote:
> > On Mon, Nov 20, 2017 at 5:22 PM Jiří Sléžka <jiri.slezka at slu.cz
> > <mailto:jiri.slezka at slu.cz>> wrote:
> >
> >     Hi,
> >
> >     I am trying realize why is exporting of vm to export storage on
> >     glusterfs such slow.
> >
> >     I am using oVirt and RHV, both instalations on version 4.1.7.
> >
> >     Hosts have dedicated nics for rhevm network - 1gbps, data storage
> itself
> >     is on FC.
> >
> >     GlusterFS cluster lives separate on 4 dedicated hosts. It has slow
> disks
> >     but I can achieve about 200-400mbit throughput in other applications
> (we
> >     are using it for "cold" data, backups mostly).
> >
> >     I am using this glusterfs cluster as backend for export storage.
> When I
> >     am exporting vm I can see only about 60-80mbit throughput.
> >
> >     What could be the bottleneck here?
> >
> >     Could it be qemu-img utility?
> >
> >     vdsm      97739  0.3  0.0 354212 29148 ?        S<l  15:43   0:06
> >     /usr/bin/qemu-img convert -p -t none -T none -f raw
> >     /rhev/data-center/2ff6d0ee-a10b-473d-b77c-be9149945f5f/
> ff3cd56a-1005-4426-8137-8f422c0b47c1/images/ba42cbcc-
> c068-4df8-af3d-00f2077b1e27/c57acd5f-d6cf-48cc-ad0c-4a7d979c0c1e
> >     -O raw
> >     /rhev/data-center/mnt/glusterSD/10.20.30.41:_rhv__
> export/81094499-a392-4ea2-b081-7c6288fbb636/images/
> ba42cbcc-c068-4df8-af3d-00f2077b1e27/c57acd5f-d6cf-48cc-ad0c-4a7d979c0c1e
> >
> >     Any idea how to make it work faster or what throughput should I
> >     expected?
> >
> >
> > gluster storage operations are using fuse mount - so every write:
> > - travel to the kernel
> > - travel back to the gluster fuse helper process
> > - travel to all 3 replicas - replication is done on client side
> > - return to kernel when all writes succeeded
> > - return to caller
> >
> > So gluster will never set any speed record.
> >
> > Additionally, you are copying from raw lv on FC - qemu-img cannot do
> > anything
> > smart and avoid copying unused clusters. Instead if copies gigabytes of
> > zeros
> > from FC.
>
> ok, it does make sense
>
> > However 7.5-10 MiB/s sounds too slow.
> >
> > I would try to test with dd - how much time it takes to copy
> > the same image from FC to your gluster storage?
> >
> > dd
> > if=/rhev/data-center/2ff6d0ee-a10b-473d-b77c-be9149945f5f/
> ff3cd56a-1005-4426-8137-8f422c0b47c1/images/ba42cbcc-
> c068-4df8-af3d-00f2077b1e27/c57acd5f-d6cf-48cc-ad0c-4a7d979c0c1e
> > of=/rhev/data-center/mnt/glusterSD/10.20.30.41:_rhv__
> export/81094499-a392-4ea2-b081-7c6288fbb636/__test__
> > bs=8M oflag=direct status=progress
>
> unfrotunately dd performs the same
>
> 1778384896 bytes (1.8 GB) copied, 198.565265 s, 9.0 MB/s
>
>
> > If dd can do this faster, please ask on qemu-discuss mailing list:
> > https://lists.nongnu.org/mailman/listinfo/qemu-discuss
> >
> > If both give similar results, I think asking in gluster mailing list
> > about this can help. Maybe your gluster setup can be optimized.
>
> ok, this is definitly on the gluster side. Thanks for your guidance.
>
> I will investigate the gluster side and also will try Export on NFS share.
>

[Adding gluster users ml]

Please provide "gluster volume info" output for the rhv_export gluster
volume and also volume profile details (refer to earlier mail from Shani on
how to run this) while performing the dd operation above.



>
> Cheers,
>
> Jiri
>
>
> >
> > Nir
> >
> >
> >
> >     Cheers,
> >
> >     Jiri
> >
> >
> >     _______________________________________________
> >     Users mailing list
> >     Users at ovirt.org <mailto:Users at ovirt.org>
> >     http://lists.ovirt.org/mailman/listinfo/users
> >
>
>
>
> _______________________________________________
> Users mailing list
> Users at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20171124/d19f4227/attachment.html>