Hi all, I have a gluster volume used to host several VMs (managed through oVirt). The volume is a replica 3 with arbiter and the 3 servers use 1 Gbit network for the storage. When testing with dd (dd if=/dev/zero of=testfile bs=1G count=1 oflag=direct) out of the volume (e.g. writing at /root/) the performance of the dd is reported to be ~ 700MB/s, which is quite decent. When testing the dd on the gluster volume I get ~ 43 MB/s which way lower from the previous. When testing with dd the gluster volume, the network traffic was not exceeding 450 Mbps on the network interface. I would expect to reach near 900 Mbps considering that there is 1 Gbit of bandwidth available. This results having VMs with very slow performance (especially on their write operations). The full details of the volume are below. Any advise on what can be tweaked will be highly appreciated. Volume Name: vms Type: Replicate Volume ID: 4513340d-7919-498b-bfe0-d836b5cea40b Status: Started Snapshot Count: 0 Number of Bricks: 1 x (2 + 1) = 3 Transport-type: tcp Bricks: Brick1: gluster0:/gluster/vms/brick Brick2: gluster1:/gluster/vms/brick Brick3: gluster2:/gluster/vms/brick (arbiter) Options Reconfigured: cluster.granular-entry-heal: enable performance.strict-o-direct: on network.ping-timeout: 30 storage.owner-gid: 36 storage.owner-uid: 36 user.cifs: off features.shard: on cluster.shd-wait-qlength: 10000 cluster.shd-max-threads: 8 cluster.locking-scheme: granular cluster.data-self-heal-algorithm: full cluster.server-quorum-type: server cluster.quorum-type: auto cluster.eager-lock: enable network.remote-dio: off performance.low-prio-threads: 32 performance.stat-prefetch: off performance.io-cache: off performance.read-ahead: off performance.quick-read: off transport.address-family: inet performance.readdir-ahead: on nfs.disable: on nfs.export-volumes: on Thanx, Alex -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20170905/51039fb5/attachment.html>
Krutika Dhananjay
2017-Sep-05 02:57 UTC
[Gluster-users] Slow performance of gluster volume
I'm assuming you are using this volume to store vm images, because I see shard in the options list. Speaking from shard translator's POV, one thing you can do to improve performance is to use preallocated images. This will at least eliminate the need for shard to perform multiple steps as part of the writes - such as creating the shard and then writing to it and then updating the aggregated file size - all of which require one network call each, which further get blown up once they reach AFR (replicate) into many more network calls. Second, I'm assuming you're using the default shard block size of 4MB (you can confirm this using `gluster volume get <VOL> shard-block-size`). In our tests, we've found that larger shard sizes perform better. So maybe change the shard-block-size to 64MB (`gluster volume set <VOL> shard-block-size 64MB`). Third, keep stat-prefetch enabled. We've found that qemu sends quite a lot of [f]stats which can be served from the (md)cache to improve performance. So enable that. Also, could you also enable client-io-threads and see if that improves performance? Which version of gluster are you using BTW? -Krutika On Tue, Sep 5, 2017 at 4:32 AM, Abi Askushi <rightkicktech at gmail.com> wrote:> Hi all, > > I have a gluster volume used to host several VMs (managed through oVirt). > The volume is a replica 3 with arbiter and the 3 servers use 1 Gbit > network for the storage. > > When testing with dd (dd if=/dev/zero of=testfile bs=1G count=1 > oflag=direct) out of the volume (e.g. writing at /root/) the performance of > the dd is reported to be ~ 700MB/s, which is quite decent. When testing the > dd on the gluster volume I get ~ 43 MB/s which way lower from the previous. > When testing with dd the gluster volume, the network traffic was not > exceeding 450 Mbps on the network interface. I would expect to reach near > 900 Mbps considering that there is 1 Gbit of bandwidth available. This > results having VMs with very slow performance (especially on their write > operations). > > The full details of the volume are below. Any advise on what can be > tweaked will be highly appreciated. > > Volume Name: vms > Type: Replicate > Volume ID: 4513340d-7919-498b-bfe0-d836b5cea40b > Status: Started > Snapshot Count: 0 > Number of Bricks: 1 x (2 + 1) = 3 > Transport-type: tcp > Bricks: > Brick1: gluster0:/gluster/vms/brick > Brick2: gluster1:/gluster/vms/brick > Brick3: gluster2:/gluster/vms/brick (arbiter) > Options Reconfigured: > cluster.granular-entry-heal: enable > performance.strict-o-direct: on > network.ping-timeout: 30 > storage.owner-gid: 36 > storage.owner-uid: 36 > user.cifs: off > features.shard: on > cluster.shd-wait-qlength: 10000 > cluster.shd-max-threads: 8 > cluster.locking-scheme: granular > cluster.data-self-heal-algorithm: full > cluster.server-quorum-type: server > cluster.quorum-type: auto > cluster.eager-lock: enable > network.remote-dio: off > performance.low-prio-threads: 32 > performance.stat-prefetch: off > performance.io-cache: off > performance.read-ahead: off > performance.quick-read: off > transport.address-family: inet > performance.readdir-ahead: on > nfs.disable: on > nfs.export-volumes: on > > > Thanx, > Alex > > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://lists.gluster.org/mailman/listinfo/gluster-users >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20170905/9c0dad3d/attachment.html>
Hi Krutika, I already have a preallocated disk on VM. Now I am checking performance with dd on the hypervisors which have the gluster volume configured. I tried also several values of shard-block-size and I keep getting the same low values on write performance. Enabling client-io-threads also did not have any affect. The version of gluster I am using is glusterfs 3.8.12 built on May 11 2017 18:46:20. The setup is a set of 3 Centos 7.3 servers and ovirt 4.1, using gluster as storage. Below are the current settings: Volume Name: vms Type: Replicate Volume ID: 4513340d-7919-498b-bfe0-d836b5cea40b Status: Started Snapshot Count: 0 Number of Bricks: 1 x (2 + 1) = 3 Transport-type: tcp Bricks: Brick1: gluster0:/gluster/vms/brick Brick2: gluster1:/gluster/vms/brick Brick3: gluster2:/gluster/vms/brick (arbiter) Options Reconfigured: server.event-threads: 4 client.event-threads: 4 performance.client-io-threads: on features.shard-block-size: 512MB cluster.granular-entry-heal: enable performance.strict-o-direct: on network.ping-timeout: 30 storage.owner-gid: 36 storage.owner-uid: 36 user.cifs: off features.shard: on cluster.shd-wait-qlength: 10000 cluster.shd-max-threads: 8 cluster.locking-scheme: granular cluster.data-self-heal-algorithm: full cluster.server-quorum-type: server cluster.quorum-type: auto cluster.eager-lock: enable network.remote-dio: off performance.low-prio-threads: 32 performance.stat-prefetch: on performance.io-cache: off performance.read-ahead: off performance.quick-read: off transport.address-family: inet performance.readdir-ahead: on nfs.disable: on nfs.export-volumes: on I observed that when testing with dd if=/dev/zero of=testfile bs=1G count=1 I get 65MB/s on the vms gluster volume (and the network traffic between the servers reaches ~ 500Mbps), while when testing with dd if=/dev/zero of=testfile bs=1G count=1 *oflag=direct *I get a consistent 10MB/s and the network traffic hardly reaching 100Mbps. Any other things one can do? On Tue, Sep 5, 2017 at 5:57 AM, Krutika Dhananjay <kdhananj at redhat.com> wrote:> I'm assuming you are using this volume to store vm images, because I see > shard in the options list. > > Speaking from shard translator's POV, one thing you can do to improve > performance is to use preallocated images. > This will at least eliminate the need for shard to perform multiple steps > as part of the writes - such as creating the shard and then writing to it > and then updating the aggregated file size - all of which require one > network call each, which further get blown up once they reach AFR > (replicate) into many more network calls. > > Second, I'm assuming you're using the default shard block size of 4MB (you > can confirm this using `gluster volume get <VOL> shard-block-size`). In our > tests, we've found that larger shard sizes perform better. So maybe change > the shard-block-size to 64MB (`gluster volume set <VOL> shard-block-size > 64MB`). > > Third, keep stat-prefetch enabled. We've found that qemu sends quite a lot > of [f]stats which can be served from the (md)cache to improve performance. > So enable that. > > Also, could you also enable client-io-threads and see if that improves > performance? > > Which version of gluster are you using BTW? > > -Krutika > > > On Tue, Sep 5, 2017 at 4:32 AM, Abi Askushi <rightkicktech at gmail.com> > wrote: > >> Hi all, >> >> I have a gluster volume used to host several VMs (managed through oVirt). >> The volume is a replica 3 with arbiter and the 3 servers use 1 Gbit >> network for the storage. >> >> When testing with dd (dd if=/dev/zero of=testfile bs=1G count=1 >> oflag=direct) out of the volume (e.g. writing at /root/) the performance of >> the dd is reported to be ~ 700MB/s, which is quite decent. When testing the >> dd on the gluster volume I get ~ 43 MB/s which way lower from the previous. >> When testing with dd the gluster volume, the network traffic was not >> exceeding 450 Mbps on the network interface. I would expect to reach near >> 900 Mbps considering that there is 1 Gbit of bandwidth available. This >> results having VMs with very slow performance (especially on their write >> operations). >> >> The full details of the volume are below. Any advise on what can be >> tweaked will be highly appreciated. >> >> Volume Name: vms >> Type: Replicate >> Volume ID: 4513340d-7919-498b-bfe0-d836b5cea40b >> Status: Started >> Snapshot Count: 0 >> Number of Bricks: 1 x (2 + 1) = 3 >> Transport-type: tcp >> Bricks: >> Brick1: gluster0:/gluster/vms/brick >> Brick2: gluster1:/gluster/vms/brick >> Brick3: gluster2:/gluster/vms/brick (arbiter) >> Options Reconfigured: >> cluster.granular-entry-heal: enable >> performance.strict-o-direct: on >> network.ping-timeout: 30 >> storage.owner-gid: 36 >> storage.owner-uid: 36 >> user.cifs: off >> features.shard: on >> cluster.shd-wait-qlength: 10000 >> cluster.shd-max-threads: 8 >> cluster.locking-scheme: granular >> cluster.data-self-heal-algorithm: full >> cluster.server-quorum-type: server >> cluster.quorum-type: auto >> cluster.eager-lock: enable >> network.remote-dio: off >> performance.low-prio-threads: 32 >> performance.stat-prefetch: off >> performance.io-cache: off >> performance.read-ahead: off >> performance.quick-read: off >> transport.address-family: inet >> performance.readdir-ahead: on >> nfs.disable: on >> nfs.export-volumes: on >> >> >> Thanx, >> Alex >> >> _______________________________________________ >> Gluster-users mailing list >> Gluster-users at gluster.org >> http://lists.gluster.org/mailman/listinfo/gluster-users >> > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20170905/ac6e6de4/attachment.html>