<div dir="ltr"><div><div><div><div><div>I'm assuming you are using this volume to store vm images, because I see shard in the options list.<br><br></div>Speaking from shard translator's POV, one thing you can do to improve performance is to use preallocated images.<br></div>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.<br><br></div>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`).<br><br></div><div>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.<br><br></div><div>Also, could you also enable client-io-threads and see if that improves performance?<br><br></div>Which version of gluster are you using BTW?<br><br></div>-Krutika<br><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Sep 5, 2017 at 4:32 AM, Abi Askushi <span dir="ltr"><<a href="mailto:rightkicktech@gmail.com" target="_blank">rightkicktech@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div>Hi all, <br><br></div>I have a gluster volume used to host several VMs (managed through oVirt). <br></div><div>The volume is a replica 3 with arbiter and the 3 servers use 1 Gbit network for the storage.</div><div><br></div><div>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). <br></div><div><br></div><div>The full details of the volume are below. Any advise on what can be tweaked will be highly appreciated. <br></div></div><div><br></div><div>Volume Name: vms<br>Type: Replicate<br>Volume ID: 4513340d-7919-498b-bfe0-<wbr>d836b5cea40b<br>Status: Started<br>Snapshot Count: 0<br>Number of Bricks: 1 x (2 + 1) = 3<br>Transport-type: tcp<br>Bricks:<br>Brick1: gluster0:/gluster/vms/brick<br>Brick2: gluster1:/gluster/vms/brick<br>Brick3: gluster2:/gluster/vms/brick (arbiter)<br>Options Reconfigured:<br>cluster.granular-entry-heal: enable<br>performance.strict-o-direct: on<br>network.ping-timeout: 30<br>storage.owner-gid: 36<br>storage.owner-uid: 36<br>user.cifs: off<br>features.shard: on<br>cluster.shd-wait-qlength: 10000<br>cluster.shd-max-threads: 8<br>cluster.locking-scheme: granular<br>cluster.data-self-heal-<wbr>algorithm: full<br>cluster.server-quorum-type: server<br>cluster.quorum-type: auto<br>cluster.eager-lock: enable<br>network.remote-dio: off<br>performance.low-prio-threads: 32<br>performance.stat-prefetch: off<br>performance.io-cache: off<br>performance.read-ahead: off<br>performance.quick-read: off<br>transport.address-family: inet<br>performance.readdir-ahead: on<br>nfs.disable: on<br>nfs.export-volumes: on<br></div><div><br></div><div><br></div><div>Thanx, <br></div><div>Alex<br></div></div>
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