From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263789AbTDUKxb (ORCPT ); Mon, 21 Apr 2003 06:53:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263811AbTDUKxb (ORCPT ); Mon, 21 Apr 2003 06:53:31 -0400 Received: from mail.ithnet.com ([217.64.64.8]:20497 "HELO heather.ithnet.com") by vger.kernel.org with SMTP id S263789AbTDUKx3 (ORCPT ); Mon, 21 Apr 2003 06:53:29 -0400 Date: Mon, 21 Apr 2003 13:03:41 +0200 From: Stephan von Krawczynski To: John Bradford Cc: vda@port.imtp.ilyichevsk.odessa.ua, john@grabjohn.com, linux-kernel@vger.kernel.org Subject: Re: Are linux-fs's drive-fault-tolerant by concept? Message-Id: <20030421130341.06d60830.skraw@ithnet.com> In-Reply-To: <200304210935.h3L9ZLXc000256@81-2-122-30.bradfords.org.uk> References: <200304210900.h3L90vu07375@Port.imtp.ilyichevsk.odessa.ua> <200304210935.h3L9ZLXc000256@81-2-122-30.bradfords.org.uk> Organization: ith Kommunikationstechnik GmbH X-Mailer: Sylpheed version 0.8.11 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 21 Apr 2003 10:35:21 +0100 (BST) John Bradford wrote: > > > > What is so bad about the simple way: the one who wants to write > > > > (e.g. fs) and knows _where_ to write simply uses another newly > > > > allocated block and dumps the old one on a blacklist. The blacklist > > > > only for being able to count them (or get the sector-numbers) in > > > > case you are interested. If you weren't you might as well mark them > > > > allocated and that's it (which I would presume a _bad_ idea). If > > > > there are no free blocks left, well, then the medium is full. And > > > > that is just about the only cause for a write error then (if the > > > > medium is writeable at all). > > > > > > Modern disks generally do this kind of thing themselves. By the time > > ^^^^^^^^^^^^ > > How many times does Stephan need to say it? 'Generally do' > > is not enough, because it means 'sometimes they dont'. > > OK, _ALL_ modern disks do. Stop this thread, we are arguing with god. > Name an IDE or SCSI disk on sale today that doesn't retry on write > failiure. Forget I said 'Generally do'. IBM DMVS18V (SCSI) Maxtor ATA133 160 GB DiamondMax Plus. Maybe they _should_, but I can tell you they in fact sometimes don't (IBM very, very seldom, Maxtor just about all the time) > > Most filesystems *are* designed with badblock lists and such, > > it is possible to teach fs drivers to tolerate write errors > > by adding affected blocks to the list and continuing (as opposed > > to 'remounted ro, BOOM!'). As usual, this can only happen if someone > > will step forward and code it. > > > > Do you think it would be a Wrong Thing to do? > > Yes, I do. > > It achieves nothing useful, and gives people a false sense of security. How do _you_ know that? What makes _you_ argue for what _I_ think is useful and _my_ sense of security? You are on thin ice ... > We have moved on since the 1980s, and I believe that it is now up to > the drive firmware, or the block device driver to do this, it has no > place in a filesystem. Interestingly I owned one of those 30 MB MFM Seagate howling drives back in the 80s. I had no errors on it until I threw it away for its unbelievable noise rate. Today I throw away one (very low-noise) disk about every week for shooting yet another fs somewhere near midnight. Indeed we moved on, only the direction looks sometimes questionable ... Regards, Stephan