From owner-freebsd-fs@FreeBSD.ORG Thu Apr 26 14:24:30 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B57941065674 for ; Thu, 26 Apr 2012 14:24:30 +0000 (UTC) (envelope-from bfriesen@simple.dallas.tx.us) Received: from blade.simplesystems.org (blade.simplesystems.org [65.66.246.74]) by mx1.freebsd.org (Postfix) with ESMTP id 719298FC14 for ; Thu, 26 Apr 2012 14:24:30 +0000 (UTC) Received: from freddy.simplesystems.org (freddy.simplesystems.org [65.66.246.65]) by blade.simplesystems.org (8.14.4+Sun/8.14.4) with ESMTP id q3QEOJou019635; Thu, 26 Apr 2012 09:24:19 -0500 (CDT) Date: Thu, 26 Apr 2012 09:24:19 -0500 (CDT) From: Bob Friesenhahn X-X-Sender: bfriesen@freddy.simplesystems.org To: Andrew Reilly In-Reply-To: <20120426034452.GB9016@johnny.reilly.home> Message-ID: References: <20120424143014.GA2865@johnny.reilly.home> <4F96BAB9.9080303@brockmann-consult.de> <20120424232136.GA1441@johnny.reilly.home> <20120426034452.GB9016@johnny.reilly.home> User-Agent: Alpine 2.01 (GSO 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (blade.simplesystems.org [65.66.246.90]); Thu, 26 Apr 2012 09:24:20 -0500 (CDT) Cc: freebsd-fs@freebsd.org Subject: Re: Odd file system corruption in ZFS pool X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Apr 2012 14:24:30 -0000 On Thu, 26 Apr 2012, Andrew Reilly wrote: > On Wed, Apr 25, 2012 at 08:58:41AM -0500, Bob Friesenhahn wrote: >> With properly implemented hardware (i.e. drives which obey the cache >> flush request) it should not be possible to corrupt zfs due to power >> failure. > > Does that comment apply to enerprise-class SATA drives? I was > under the impression that all SATA drives lied about cache flush > status. Hence the notion that I need to get myself a UPS. A blanket statement like that (about SATA drives) would not be very accurate. UPSs are quite valuable in that they help the system avoid marginal operating conditions. If power is lost while a drive is currently writing, perhaps it will move the head to the wrong position and write to the wrong place on the disk, or perhaps the data it does write will be junk. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/