Date: Wed, 05 Nov 2014 16:36:11 +0100 From: Erik Stian Tefre <erik@tefre.com> To: freebsd-fs@freebsd.org Subject: Re: Differences in memory handling on systems with/out cache drives Message-ID: <545A43EB.7070603@tefre.com> In-Reply-To: <5F9E965F5A80BC468BE5F40576769F099DF87FBB@exchange2-1> References: <5F9E965F5A80BC468BE5F40576769F099DF87F57@exchange2-1> <5F9E965F5A80BC468BE5F40576769F099DF87FBB@exchange2-1>
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On 05. nov. 2014 09:53, Karli Sjöberg wrote: > On Wed, 2014-11-05 at 08:44 +0000, Karli Sjöberg wrote: >> Hey all! >> >> Still investigating the intermittent lockups we are experiencing on our >> storage systems and have started to compare memory graphs from our >> Graphite monitoring system. What´s interesting about two of our systems >> is that they both have the same amount of RAM; 32 GB. But on one of >> them, I have "zpool remove"'d the cache drives from the pool and have >> been able to study how different their memory graphs now look like. >> >> Also worth noting is that the cache-less system nearly haven´t swapped >> at all (1112K) since the last stall 20 days ago, while the other system >> has swapped 78 MB during it´s 48 days of uptime. >> >> I´ve attached both screenshots from the two systems, with- and without >> cache drives, displaying a period of 12 hours. >> >> What´s most notable are the characteristic cuts that happen on the >> cache-less system when ZFS goes in and evicts blocks from ARC that shows >> as a decrease in "wired" and increase in "free", that just doesn´t >> happen/looks different in the system with cache drive configured in the >> pool. >> >> What´s your take on this? Are we hitting bug: 187594 perhaps? How can we >> know? Take a look at the recent thread on freebsd-stable@, subject "ARC size limit". Possibly related issues have been patched in stable/10, the mailing list thread includes a patch for releng/10.1. -- Erik
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