From owner-freebsd-fs@FreeBSD.ORG Wed Apr 25 13:58:54 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 BB9CF106566C for ; Wed, 25 Apr 2012 13:58:54 +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 7BCAE8FC16 for ; Wed, 25 Apr 2012 13:58:54 +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 q3PDwfmN014482; Wed, 25 Apr 2012 08:58:42 -0500 (CDT) Date: Wed, 25 Apr 2012 08:58:41 -0500 (CDT) From: Bob Friesenhahn X-X-Sender: bfriesen@freddy.simplesystems.org To: Andrew Reilly In-Reply-To: <20120424232136.GA1441@johnny.reilly.home> Message-ID: References: <20120424143014.GA2865@johnny.reilly.home> <4F96BAB9.9080303@brockmann-consult.de> <20120424232136.GA1441@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]); Wed, 25 Apr 2012 08:58:42 -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: Wed, 25 Apr 2012 13:58:54 -0000 On Wed, 25 Apr 2012, Andrew Reilly wrote: > from corruption (boot panic loop after a zpool scrub) a year or > so ago, so the current system is new since then. The first had > been upgraded at least once, not sure about the current. Has > only ever been attached to this (regularly upgraded) _STABLE > system. It isn't protected by a UPS, and the power has been > going out without warning fairly regularly, so IMO that is > sufficient to explain the cause of the corruption. Setting up a > UPS is my next project. 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. Some of the most recently written data may be lost, but zfs should come up totally coherent at some point in the recent past. It is important to use a system which supports ECC memory to assure that data is not corrupted in memory since zfs does not defend against that. Storage redundancy is necessary to correct any data read errors but should not be necessary to defend against the result of power failure. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/