On Mon, Feb 27, 2017 at 12:34:23PM -0800, Ernie Dunbar wrote: > Hi everyone! > > After a bit of an ordeal with our Gluster servers last week, I discovered > some very important coincidences that can very badly affect Gluster > performance when they occur. > > Should the Mlocate updater start when Gluster is going through the > self-heal process, especially one that is very long (ours can take a few > days sometimes), Gluster's performance can become extremely poor with > symptoms of high server load, moderate to high CPU usage, high disk IO > activity, and occasional to lengthy times where there is 100% disk > utilization. IO Wait times on any clients can be high to extreme. Memory > usage might also be higher than normal, and on servers with less than say, > 8 GB of RAM, this might cause RAM to be swapped to disk, exacerbating the > problem further. > > The Mlocate update program "updatedb" is installed by default on most > Linux implementations, and is run nightly by default in the daily cron > jobs. I have added a new file to the Gluster installation documentation > (named "post-installation") with the recommendation that this daily cron > job be removed. Removing this job would have little to no impact on the > operation of Gluster's operating system. > > If anyone would like to test and verify this in a non-production > environment, be my guest. You are absolutely correct. We have seen problems with this before, and I have filed a bug for Fedora to get this fixed in mlocate: https://bugzilla.redhat.com/show_bug.cgi?id=1331944 Other distributions probably need a similar fix. I recommend other users to check the mlocate package for their distribution and report bugs against them too. It will help others if everyone that reports a bug replies to this email so that all links are archived in the mailinglist. Thanks! Niels
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