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[47.135.146.236]) by smtp.gmail.com with ESMTPSA id h10-v6sm9540557ywa.35.2018.09.21.08.17.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Sep 2018 08:17:44 -0700 (PDT) From: Josh Gitlin Message-Id: <373102CE-B53A-4547-8665-DF5EC74C23DD@goboomtown.com> Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: Troubleshooting kernel panic with zfs Date: Fri, 21 Sep 2018 11:17:43 -0400 In-Reply-To: To: freebsd-fs@freebsd.org References: X-Mailer: Apple Mail (2.3445.9.1) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.27 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Sep 2018 15:17:46 -0000 Thanks for the help Mike! In reviewing our settings I also found that = we're setting vm.kmem_size to 1.5x physical RAM installed, based on a = tuning guide someone found. I personally believe that might be misguided = and may be related to the panic we saw, as this causes zfs-stats -a to = show the kernel memory map being larger than system RAM: Kernel Memory Map: 24.00 GiB Size: 21.72% 5.21 GiB Free: 78.28% 18.79 GiB I'll try tuning these settings down and see if the problem happens = again. Appreciate the support! -- =09 Josh Gitlin Senior DevOps Engineer (415) 690-1610 x155 Stay up to date and join the conversation in Relay = . > On Sep 21, 2018, at 9:04 AM, Mike Tancsa wrote: >=20 > On 9/20/2018 8:27 PM, Josh Gitlin wrote: >>=20 >> My hunch is that, given this was inside kmem_malloc, we were unable = to allocate memory for a zio_write_compress call (the pool does have ZFS = compression on) and hence this is a tuning issue and not a bug... but I = am looking for confirmation and/or suggested changes/troubleshooting = steps. The ZFS tuning configuration has been stable for years, to it may = be a change in behavior or traffic... If this looks like it might be a = bug, I will be able to get more information from a minidump if it = reoccurs and can follow up on this thread. >=20 > Given all the issues with memory pressure perhaps ARC is eating too > much, I would try artificially limiting it so it does not eat up too > much RAM. We had a similar purposed server but with 32G RAM and I = found > one day the system was randomly shooting processes to reclaim RAM >=20 > eg > pid xxx (yyy), uid zzzz, was killed: out of swap space >=20 >=20 > Perhaps >=20 > sysctl -w vfs.zfs.arc_max=3D6000000000 >=20 > eg. > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D229764 >=20 > = https://lists.freebsd.org/pipermail/freebsd-questions/2018-July/282261.htm= l >=20 > ---Mike >=20 >=20 >=20 >=20 > --=20 > ------------------- > Mike Tancsa, tel +1 519 651 3400 x203 > Sentex Communications, mike@sentex.net > Providing Internet services since 1994 www.sentex.net > Cambridge, Ontario Canada