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

Hi, On 11/22/2017 07:30 PM, Nir Soffer wrote: > On Mon, Nov 20, 2017 at 5:22 PM Jiří Sléžka <jiri.slezka(a)slu.cz > <mailto:jiri.slezka@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.

Cheers, Jiri > > Nir > > > > Cheers, > > Jiri > > > _______________________________________________ > Users mailing list > Users(a)ovirt.org <mailto:Users@ovirt.org> > http://lists.ovirt.org/mailman/listinfo/users > _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users