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<div class="moz-cite-prefix">Hi Pat,<br>
<br>
I'm assuming you are using gluster native (fuse mount). If it
helps, you could try mounting it via gluster NFS (gnfs) and then
see if there is an improvement in speed. Fuse mounts are slower
than gnfs mounts but you get the benefit of avoiding a single
point of failure. Unlike fuse mounts, if the gluster node
containing the gnfs server goes down, all mounts done using that
node will fail). For fuse mounts, you could try tweaking the
write-behind xlator settings to see if it helps. See the
performance.write-behind and performance.write-behind-window-size
options in `gluster volume set help`. Of course, even for gnfs
mounts, you can achieve fail-over by using CTDB.<br>
<br>
Thanks,<br>
Ravi<br>
<br>
On 04/08/2017 12:07 AM, Pat Haley wrote:<br>
</div>
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type="cite">
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<br>
Hi,<br>
<br>
We noticed a dramatic slowness when writing to a gluster disk when
compared to writing to an NFS disk. Specifically when using dd
(data duplicator) to write a 4.3 GB file of zeros:<br>
<ul>
<li>on NFS disk (/home): 9.5 Gb/s</li>
<li>on gluster disk (/gdata): 508 Mb/s<br>
</li>
</ul>
The gluser disk is 2 bricks joined together, no replication or
anything else. The hardware is (literally) the same:<br>
<ul>
<li>one server with 70 hard disks and a hardware RAID card.</li>
<li>4 disks in a RAID-6 group (the NFS disk)</li>
<li>32 disks in a RAID-6 group (the max allowed by the card,
/mnt/brick1)</li>
<li>32 disks in another RAID-6 group (/mnt/brick2)</li>
<li>2 hot spare<br>
</li>
</ul>
<p>Some additional information and more tests results (after
changing the log level):<br>
</p>
<p><span>glusterfs 3.7.11 built on Apr 27 2016 14:09:22</span><br>
<span>CentOS release 6.8 (Final)</span><br>
RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS-3
3108 [Invader] (rev 02)<br>
<br>
<br>
<br>
<b>Create the file to /gdata (gluster)</b><br>
[root@mseas-data2 gdata]# dd if=/dev/zero of=/gdata/zero1 bs=1M
count=1000<br>
1000+0 records in<br>
1000+0 records out<br>
1048576000 bytes (1.0 GB) copied, 1.91876 s, <b>546 MB/s</b><br>
<br>
<b>Create the file to /home (ext4)</b><br>
[root@mseas-data2 gdata]# dd if=/dev/zero of=/home/zero1 bs=1M
count=1000<br>
1000+0 records in<br>
1000+0 records out<br>
1048576000 bytes (1.0 GB) copied, 0.686021 s, <b>1.5 GB/s - </b>3
times as fast<b><br>
<br>
<br>
Copy from /gdata to /gdata (gluster to gluster)<br>
</b>[root@mseas-data2 gdata]# dd if=/gdata/zero1 of=/gdata/zero2<br>
2048000+0 records in<br>
2048000+0 records out<br>
1048576000 bytes (1.0 GB) copied, 101.052 s, <b>10.4 MB/s</b> -
realllyyy slooowww<br>
<br>
<br>
<b>Copy from /gdata to /gdata</b> <b>2nd time <b>(gluster to
gluster)</b></b><br>
[root@mseas-data2 gdata]# dd if=/gdata/zero1 of=/gdata/zero2<br>
2048000+0 records in<br>
2048000+0 records out<br>
1048576000 bytes (1.0 GB) copied, 92.4904 s, <b>11.3 MB/s</b> <span>-
realllyyy slooowww</span> again<br>
<br>
<br>
<br>
<b>Copy from /home to /home (ext4 to ext4)</b><br>
[root@mseas-data2 gdata]# dd if=/home/zero1 of=/home/zero2<br>
2048000+0 records in<br>
2048000+0 records out<br>
1048576000 bytes (1.0 GB) copied, 3.53263 s, <b>297 MB/s </b>30
times as fast<br>
<br>
<br>
<b>Copy from /home to /home (ext4 to ext4)</b><br>
[root@mseas-data2 gdata]# dd if=/home/zero1 of=/home/zero3<br>
2048000+0 records in<br>
2048000+0 records out<br>
1048576000 bytes (1.0 GB) copied, 4.1737 s, <b>251 MB/s</b> <span>-
30 times as fast<br>
<br>
<br>
As a test, can we copy data directly to the xfs mountpoint
(/mnt/brick1) and bypass gluster?<br>
<br>
<br>
Any help you could give us would be appreciated.<br>
<br>
</span>Thanks<br>
</p>
<pre class="moz-signature" cols="72">--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley Email: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:phaley@mit.edu">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
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