From owner-freebsd-hackers Mon Jul 8 17:50: 6 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7920437B400 for ; Mon, 8 Jul 2002 17:50:00 -0700 (PDT) Received: from patrocles.silby.com (d180.as20.nwbl0.wi.voyager.net [169.207.139.182]) by mx1.FreeBSD.org (Postfix) with ESMTP id 488FD43E09 for ; Mon, 8 Jul 2002 17:49:59 -0700 (PDT) (envelope-from silby@silby.com) Received: from patrocles.silby.com (localhost [127.0.0.1]) by patrocles.silby.com (8.12.4/8.12.4) with ESMTP id g690rRcv020194; Mon, 8 Jul 2002 19:53:27 -0500 (CDT) (envelope-from silby@silby.com) Received: from localhost (silby@localhost) by patrocles.silby.com (8.12.4/8.12.4/Submit) with ESMTP id g690rGum020191; Mon, 8 Jul 2002 19:53:16 -0500 (CDT) X-Authentication-Warning: patrocles.silby.com: silby owned process doing -bs Date: Mon, 8 Jul 2002 19:53:16 -0500 (CDT) From: Mike Silbersack To: Peter Wemm Cc: Julian Elischer , John Nielsen , Subject: Re: offtopic: low level format of IDE drive. In-Reply-To: <20020708233721.DC2C33808@overcee.wemm.org> Message-ID: <20020708195133.K19349-100000@patrocles.silby.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Mon, 8 Jul 2002, Peter Wemm wrote: > The thing is, just about all IDE drives more than a few GB or so do 'track > writing' and have no fixed sectoring or sector positioning. ie: each time > you write a single sector to a track, it does a read-modify-write of *THE > ENTIRE TRACK*. This is why we have to have write caching turned on for IDE > The sad thing is that this makes softdep almost completely useless, because > the basic assumption is that sectors that were not explicitly written to > will not be touched. The problem is that this isn't the case, even with > write caching turned off. Writing a single sector causes the drive to > completely rebuild the track and all the sectors on it... in a different So, this basically means that even a journalling filesystem wouldn't be much safer... how about battery backed up controllers - would those provide protection? (I suspect not, but maybe they're more sophisticated than I thought.) Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message