From owner-freebsd-questions@freebsd.org Wed Sep 9 16:10:02 2015 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 557479CCA87 for ; Wed, 9 Sep 2015 16:10:02 +0000 (UTC) (envelope-from wam@hiwaay.net) Received: from fly.hiwaay.net (fly.hiwaay.net [216.180.54.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 08BB01EF5 for ; Wed, 9 Sep 2015 16:10:01 +0000 (UTC) (envelope-from wam@hiwaay.net) Received: from kabini1.local (dynamic-216-186-222-143.knology.net [216.186.222.143] (may be forged)) (authenticated bits=0) by fly.hiwaay.net (8.13.8/8.13.8/fly) with ESMTP id t89GA0Z7019706 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Wed, 9 Sep 2015 11:10:00 -0500 Subject: Re: Storage question To: FreeBSD Questions References: <55EF3D23.5060009@hiwaay.net> <20150908220639.20412cbd@gumby.homeunix.com> <55EF5409.8020007@yahoo.com> <55EFC2DA.3020101@hiwaay.net> <08B351DD-AA48-4F30-B0D6-C500D0877FB3@lafn.org> <55F02DC8.7000706@hiwaay.net> <20150909150626.5c3b99e5.freebsd@edvax.de> <55F031A0.40500@hiwaay.net> <20150909145820.c3b48aafad4f70553c1c1fd8@sohara.org> <55F0451A.5080709@hiwaay.net> <20150909160005.d3b84775c3d0748014a871e5@sohara.org> <55F04D78.8070508@hiwaay.net> From: "William A. Mahaffey III" Message-ID: <55F059D8.5000101@hiwaay.net> Date: Wed, 9 Sep 2015 11:15:30 -0453.75 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Sep 2015 16:10:02 -0000 On 09/09/15 10:51, Paul Kraus wrote: > Swap on zvol is a bad idea (as you may have already found). The issue, as best I can tell, is that since ZFS grabs all the RAM it can, and SWAP is used in low RAM situations, there are times were SWAP is trying to write to the zvol and ZFS is trying to decrease it’s RAM usage (because of memory pressure) so it’s performance drops. Functionally it becomes a race state that ends badly. Yeah, I figured that out *right* after I hit the 'return' key ;-) .... -- William A. Mahaffey III ---------------------------------------------------------------------- "The M1 Garand is without doubt the finest implement of war ever devised by man." -- Gen. George S. Patton Jr.