From owner-freebsd-stable@FreeBSD.ORG Tue Mar 5 03:54:43 2013 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 95DA331D for ; Tue, 5 Mar 2013 03:54:43 +0000 (UTC) (envelope-from dg@pki2.com) Received: from btw.pki2.com (btw.pki2.com [IPv6:2001:470:a:6fd::2]) by mx1.freebsd.org (Postfix) with ESMTP id 44072D6D for ; Tue, 5 Mar 2013 03:54:43 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by btw.pki2.com (8.14.6/8.14.5) with ESMTP id r253sTT7079185; Mon, 4 Mar 2013 19:54:29 -0800 (PST) (envelope-from dg@pki2.com) Subject: Re: ZFS "stalls" -- and maybe we should be talking about defaults? From: Dennis Glatting To: Steven Hartland In-Reply-To: <8C68812328E3483BA9786EF15591124D@multiplay.co.uk> References: <513524B2.6020600@denninger.net> <1362449266.92708.8.camel@btw.pki2.com> <51355F64.4040409@denninger.net> <8C68812328E3483BA9786EF15591124D@multiplay.co.uk> Content-Type: text/plain; charset="ISO-8859-1" Date: Mon, 04 Mar 2013 19:54:29 -0800 Message-ID: <1362455669.62624.12.camel@btw.pki2.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit X-yoursite-MailScanner-Information: Dennis Glatting X-yoursite-MailScanner-ID: r253sTT7079185 X-yoursite-MailScanner: Found to be clean X-MailScanner-From: dg@pki2.com Cc: freebsd-stable@freebsd.org, Karl Denninger X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Mar 2013 03:54:43 -0000 On Tue, 2013-03-05 at 03:25 +0000, Steven Hartland wrote: > ----- Original Message ----- > From: "Karl Denninger" > > > Stick this in /boot/loader.conf and see if your lockups goes away: > > > > vfs.zfs.write_limit_override=1024000000 > ... > > > If it turns out that the write_limit_override tunable is the one > > responsible for stopping the hangs I can drop the ARC limit tunable > > although I'm not sure I want to; I don't see much if any performance > > penalty from leaving it where it is and if the larger cache isn't > > helping anything then why use it? I'm inclined to stick an SSD in the > > cabinet as a cache drive instead of dedicating RAM to this -- even > > though it's not AS fast as RAM it's still MASSIVELY quicker than getting > > data off a rotating plate of rust. > > Now interesting you should say that I've seen a stall recently on ZFS > only box running on 6 x SSD RAIDZ2. > > The stall was caused by fairly large mysql import, with nothing else > running. > > Then it happened I thought the machine had wedged, but minutes (not > seconds) later, everything sprung into action again. > I've seen this too. > > Am I correct that a ZFS filesystem does NOT use the VM buffer cache > > at all? > > Correct > > Regards > Steve > > ================================================ > This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. > > In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337 > or return the E.mail to postmaster@multiplay.co.uk. > > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" -- Dennis Glatting