Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261568AbVETUaE (ORCPT ); Fri, 20 May 2005 16:30:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261574AbVETUaD (ORCPT ); Fri, 20 May 2005 16:30:03 -0400 Received: from alpha.polcom.net ([217.79.151.115]:55465 "EHLO alpha.polcom.net") by vger.kernel.org with ESMTP id S261568AbVETU22 (ORCPT ); Fri, 20 May 2005 16:28:28 -0400 Date: Fri, 20 May 2005 22:36:26 +0200 (CEST) From: Grzegorz Kulewski To: Lennart Sorensen Cc: Adam Miller , linux-kernel@vger.kernel.org Subject: Re: software RAID In-Reply-To: <20050520200334.GF23621@csclub.uwaterloo.ca> Message-ID: References: <20050520200334.GF23621@csclub.uwaterloo.ca> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1655 Lines: 34 On Fri, 20 May 2005, Lennart Sorensen wrote: > On Fri, May 20, 2005 at 12:56:13PM -0500, Adam Miller wrote: >> We're looking to set up either software RAID 1 or RAID 10 using 2 SATA >> disks. If a disk in drive A has a bad sector, can it be setup so that the >> array will read the sector from drive B and then have it rewrite the >> bad sector on drive A? Please CC me in the response. > > If a harddisk has a bad sector that is visible to the user (and hence > not remapped by the drive) then it is time to retire the drive since it > is out of spares and very damaged by that point. > > If you have a bad sector, it doesn't go away by writing to it again. On > modern drives, if you see bad sectors the disk is just about dead, and > will probably be seen as such by the raid system which will then stop > using the disk entirely and expect you to replace it ASAP. What do you mean "see bad sectors"? Modern drives are trying to relocate sectors that can become bad in short time. But this does not work 100% reliably. And sometimes disk wants to relocate sector but the sector can not be read anymore. If this happens disk will return read error when reading the sector _but_ when you will write it again it will relocate it (with new data). And I think this was the idea behind first post... To allow disk A to relocate not readable sectors with correct data from disk B. Grzegorz Kulewski - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/