From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: XFS corruption during power-blackout Date: Mon, 11 Jul 2005 08:53:21 -0400 Message-ID: <42D26BC1.30008@emc.com> References: <42C54BDC.6000206@emc.com> <20050701184145.GA3055@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Bryan Henderson , linux-fsdevel@vger.kernel.org, =?ISO-8859-1?Q?Rog=E9rio_Brito?= , Brett Russ Return-path: Received: from mailhub.lss.emc.com ([168.159.2.31]:64231 "EHLO mailhub.lss.emc.com") by vger.kernel.org with ESMTP id S261669AbVGKMxf (ORCPT ); Mon, 11 Jul 2005 08:53:35 -0400 To: Jens Axboe In-Reply-To: <20050701184145.GA3055@suse.de> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Jens Axboe wrote: >On Fri, Jul 01 2005, Bryan Henderson wrote: > > >>Wouldn't a commercial class drive that ignores explicit flushes be >>infamous? I'm ready to accept that there are SCSI drives that cache >>writes in volatile storage by default (but frankly, I'm still skeptical), >>but I'm not ready to accept that there are drives out there secretly >>ignoring explicit commands to harden data, thus jeopardizing millions of >>dollars' worth of data. I'd need more evidence. >> >> > >I'm pretty sure I have an IBM drive that does so (its flush cache >command is _really_ fast), as a matter of fact :-) I need to locate it >and put it in a test box to re-ensure this. > >I'm not sure such drives would necessarily be infamous, hardly anyone >would notice anything wrong in a desktop type machine. Which is what >these drives were made for. > > One other thing to keep in mind is that drive firmware can have bugs just like any other bit of code, so a drive may have a bug in one firmware revision that gets fixed in a following one. I am not sure how much that other operating system uses flush cache commands, but until the write barrier patch, it has been a relatively rarely issued command for Linux and breakage would not be noticed.