From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263335AbTJUUg7 (ORCPT ); Tue, 21 Oct 2003 16:36:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263337AbTJUUg6 (ORCPT ); Tue, 21 Oct 2003 16:36:58 -0400 Received: from tmr-02.dsl.thebiz.net ([216.238.38.204]:14084 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id S263335AbTJUUg5 (ORCPT ); Tue, 21 Oct 2003 16:36:57 -0400 To: linux-kernel@vger.kernel.org Path: gatekeeper.tmr.com!davidsen From: davidsen@tmr.com (bill davidsen) Newsgroups: mail.linux-kernel Subject: Re: Blockbusting news, this is important (Re: Why are bad disk sectors numbered strangely, and what happens to them?) Date: 21 Oct 2003 20:26:56 GMT Organization: TMR Associates, Schenectady NY Message-ID: References: <20031018074223.GN1659@openzaurus.ucw.cz> <200310180830.h9I8ULuc000419@81-2-122-30.bradfords.org.uk> X-Trace: gatekeeper.tmr.com 1066768016 19146 192.168.12.62 (21 Oct 2003 20:26:56 GMT) X-Complaints-To: abuse@tmr.com Originator: davidsen@gatekeeper.tmr.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <200310180830.h9I8ULuc000419@81-2-122-30.bradfords.org.uk>, John Bradford wrote: | > > BTW: Hard drives apparently use more sophisticated algorithms, | > > involving measuring head signal level even when there is no problem | > > reading the data, and eventually remapping a sector on read before the | > > information is lost. | > > | > | > Which means cat /dev/hda > /dev/null makes sense in | > cron.weekly... | | Indeed. Some drives can also do a timed defect scan using S.M.A.R.T. You make the point I was going to question, is the cat (dd?) better than a S.M.A.R.T. scan? I would think that the scan would be more likely to be doing some special error checking, like turning off one level of ECC or similar, and might see things a normal read might not. In other words, the difference between no uncorrectable errors and no errors. I am thinking of something like a C2 scan on a CD, to get error detection without error correction. -- bill davidsen CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.