From owner-freebsd-fs@FreeBSD.ORG Tue Oct 23 15:40:26 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 1A717753 for ; Tue, 23 Oct 2012 15:40:26 +0000 (UTC) (envelope-from dustinwenz@ebureau.com) Received: from internet02.ebureau.com (internet02.tru-signal.biz [65.127.24.21]) by mx1.freebsd.org (Postfix) with ESMTP id C7B018FC0C for ; Tue, 23 Oct 2012 15:40:25 +0000 (UTC) Received: from service02.office.ebureau.com (internet06.ebureau.com [65.127.24.25]) by internet02.ebureau.com (Postfix) with ESMTP id 2A596DF392F for ; Tue, 23 Oct 2012 10:40:19 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by service02.office.ebureau.com (Postfix) with ESMTP id 26146B1F663 for ; Tue, 23 Oct 2012 10:40:19 -0500 (CDT) X-Virus-Scanned: amavisd-new at ebureau.com Received: from service02.office.ebureau.com ([127.0.0.1]) by localhost (internet06.ebureau.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fFrNC2988rE4 for ; Tue, 23 Oct 2012 10:40:16 -0500 (CDT) Received: from square.office.ebureau.com (square.office.ebureau.com [10.10.20.22]) by service02.office.ebureau.com (Postfix) with ESMTPSA id CF3DEB1F641 for ; Tue, 23 Oct 2012 10:40:16 -0500 (CDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.1 \(1498\)) Subject: Re: Imposing ZFS latency limits From: Dustin Wenz In-Reply-To: Date: Tue, 23 Oct 2012 10:40:16 -0500 Content-Transfer-Encoding: quoted-printable Message-Id: <2CB1D556-1EAF-43F9-8A24-36548C663ED8@ebureau.com> References: <6116A56E-4565-4485-887E-46E3ED231606@ebureau.com> <089898A4493042448C934643FD5C3887@multiplay.co.uk> To: "" X-Mailer: Apple Mail (2.1498) 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, 23 Oct 2012 15:40:26 -0000 On Oct 22, 2012, at 8:21 AM, Mark Felder wrote: > On Tue, 16 Oct 2012 10:46:00 -0500, Steven Hartland = wrote: >=20 >>=20 >> Interesting, what metrics where you using which made it easy to = detect, >> work be nice to know your process there Mark? >=20 > One reason is that our virtual machine performance gets awful and we = get alerted for higher than usual load and/or disk io latency by the = hypervisor. Another thing we've implemented is watching for some SCSI = errors on the server too. They seem to let us know before it really gets = bad. >=20 > It's nice knowing ZFS is doing everything within its power to read the = data off the disk, but when there's a fully intact raidz it should be = smart enough to kick a disk out that's being problematic. What hypervisor are you using? Is it with a passive JBOD? There are other situations where a disk is not failing that you may not = get constant read performance, such as when a disk is undergoing thermal = recalibration, being scanned for diagnostics, etc. Any sort of realtime = database or streaming application could benefit from better latency = control. It's possible that we have no control over this, and are subject to = whatever features Oracle decides to include or omit from ZFS. - .Dustin