OK my understanding is that with preallocated disks the performance with and without shard will be the same.
In any case, please attach the volume profile[1], so we can see what else is slowing things down. -Krutika [1] - https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Monitoring%20Workload/#running-glusterfs-volume-profile-command On Tue, Sep 5, 2017 at 2:32 PM, Abi Askushi <[email protected]> wrote: > 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 <[email protected]> > 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 <[email protected]> >> 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 >>> [email protected] >>> http://lists.gluster.org/mailman/listinfo/gluster-users >>> >> >> >
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