On Mon, Nov 20, 2017 at 5:22 PM Jiří Sléžka <jiri.sle...@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. 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 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. Nir > > Cheers, > > Jiri > > > _______________________________________________ > Users mailing list > Users@ovirt.org > http://lists.ovirt.org/mailman/listinfo/users >
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