From owner-freebsd-fs@FreeBSD.ORG Tue Apr 9 12:15:15 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id D1EEBBB6 for ; Tue, 9 Apr 2013 12:15:15 +0000 (UTC) (envelope-from gallasch@free.de) Received: from smtp.free.de (smtp.free.de [91.204.6.103]) by mx1.freebsd.org (Postfix) with ESMTP id 478B26B4 for ; Tue, 9 Apr 2013 12:15:15 +0000 (UTC) Received: (qmail 73868 invoked from network); 9 Apr 2013 14:15:08 +0200 Received: from smtp.free.de (HELO orwell.free.de) (gallasch@free.de@[91.204.4.103]) (envelope-sender ) by smtp.free.de (qmail-ldap-1.03) with AES128-SHA encrypted SMTP for ; 9 Apr 2013 14:15:08 +0200 Subject: Re: FreeBSD 9.1 and swap on zfs Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: text/plain; charset=us-ascii From: Kai Gallasch In-Reply-To: <5162CBE8.5050104@madpilot.net> Date: Tue, 9 Apr 2013 14:15:06 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <9407C6ED-3B4C-4BA2-8B88-F8A998E0A847@free.de> <5162CBE8.5050104@madpilot.net> To: Guido Falsi X-Mailer: Apple Mail (2.1085) Cc: freebsd-fs@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Apr 2013 12:15:15 -0000 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.=