Date: Tue, 9 Apr 2013 14:15:06 +0200 From: Kai Gallasch <gallasch@free.de> To: Guido Falsi <mad@madpilot.net> Cc: freebsd-fs@freebsd.org Subject: Re: FreeBSD 9.1 and swap on zfs Message-ID: <AF006790-64C2-49AA-9ED2-32917F514565@free.de> In-Reply-To: <5162CBE8.5050104@madpilot.net> References: <9407C6ED-3B4C-4BA2-8B88-F8A998E0A847@free.de> <5162CBE8.5050104@madpilot.net>
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Am 08.04.2013 um 15:53 schrieb Guido Falsi: > On 04/08/13 15:08, Kai Gallasch wrote: >> Hi. >>=20 >> When running a ZFS on root FreeBSD install.. >>=20 >> is it for FreeBSD 9.1 (ZFS v28) still not advisable to use a vdev as = swapspace? - like: > I can share my experience, which is not definitive but I hope can = help. thank you! > I have various machines with ZFS on root. some with swap on ZVOL and = some with swap on separate partitions (none are mirroring the swap using = gmirror though). >=20 > There is a race condition between ZFS' ARC and the VM system when very = low memory conditions arise and this could happen and the machine just = starves, I've seen this happen on machines when running buildworld -j = without enough ram and also on machines running ports tinderbox or = poudriere. This is not happening when using a separate swap partition. = In such a case the machine swaps happily and just slows down as = naturally expected when swapping a lot. Do you also have machines running on 9.1 that swap on ZVOL and which = show this behaviour? > My suggestion is: >=20 > if you want stability and don't have specific disk layout problems = create a separate swap. I think I'll repartition and swap to a gmirror device then. This also has the advantage of being able to write kernel dumps to the = swap (not possible with a ZVOL bases swap AFAIK) Kai.=
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