On Thu, Nov 23, 2017 at 4:56 PM, Jiří Sléžka <jiri.slezka@xxxxxx> 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@xxxxxx
ok, it does make sense> <mailto:jiri.slezka@xxxxxx>> 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.
> 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/ unfrotunately dd performs the sameff3cd56a-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
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
>
>
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