From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Lord Subject: Re: XFS corruption during power-blackout Date: Wed, 29 Jun 2005 12:56:12 -0500 Message-ID: <42C2E0BC.8040508@xfs.org> References: <20050629001847.GB850@frodo> <200506290453.HAA14576@raad.intranet> <556815.441dd7d1ebc32b4a80e049e0ddca5d18e872c6e8a722b2aefa7525e9504533049d801014.ANY@taniwha.stupidest.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Al Boldi , 'Nathan Scott' , linux-xfs@oss.sgi.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, reiserfs-list@namesys.com Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com To: Chris Wedgwood In-Reply-To: <556815.441dd7d1ebc32b4a80e049e0ddca5d18e872c6e8a722b2aefa7525e9504533049d801014.ANY@taniwha.stupidest.org> List-Id: linux-fsdevel.vger.kernel.org Chris Wedgwood wrote: > On Wed, Jun 29, 2005 at 07:53:09AM +0300, Al Boldi wrote: > > >>What I found were 4 things in the dest dir: >>1. Missing Dirs,Files. That's OK. >>2. Files of size 0. That's acceptable. >>3. Corrupted Files. That's unacceptable. >>4. Corrupted Files with original fingerprint. That's ABSOLUTELY >>unacceptable. > > > disk usually default to caching these days and can lose data as a > result, disable that > There are IDE drives where the vendor will tell you that you will drasticly shorten the life of a drive if you turn off caching. There are also cool bits of technology which use the rotational energy of the spinning down drive to dump the cache out to a special track (or this may be an urban legend, not sure). Problem is, no one but the vendors really knows what any particular disk is going to do when you pull the plug. I did spend a bunch of time once ensuring that when you typed sync on xfs you could pull the power right after that and everything from before the sync survived. There have been a lot of changes both in xfs and the surrounding kernel since then. I do not know if anyone has attempted this effort again recently. If you care sufficiently about your data to want to do power fail testing then, even assuming the filesystem works perfectly: a) have a working, tested, regular backup policy b) keep the backups in a different building c) buy a UPS. Steve