From owner-freebsd-questions@FreeBSD.ORG Mon Jun 16 14:54:24 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5FDC61065704 for ; Mon, 16 Jun 2008 14:54:24 +0000 (UTC) (envelope-from erikt@midgard.homeip.net) Received: from ch-smtp01.sth.basefarm.net (ch-smtp01.sth.basefarm.net [80.76.149.212]) by mx1.freebsd.org (Postfix) with ESMTP id 144248FC0A for ; Mon, 16 Jun 2008 14:54:23 +0000 (UTC) (envelope-from erikt@midgard.homeip.net) Received: from c83-253-25-183.bredband.comhem.se ([83.253.25.183]:65068 helo=falcon.midgard.homeip.net) by ch-smtp01.sth.basefarm.net with esmtp (Exim 4.68) (envelope-from ) id 1K8G6A-0001mb-4T for freebsd-questions@freebsd.org; Mon, 16 Jun 2008 16:54:22 +0200 Received: (qmail 25672 invoked from network); 16 Jun 2008 16:54:20 +0200 Received: from owl.midgard.homeip.net (10.1.5.7) by falcon.midgard.homeip.net with ESMTP; 16 Jun 2008 16:54:20 +0200 Received: (qmail 26695 invoked by uid 1001); 16 Jun 2008 16:54:20 +0200 Date: Mon, 16 Jun 2008 16:54:20 +0200 From: Erik Trulsson To: Wojciech Puchar Message-ID: <20080616145420.GA26679@owl.midgard.homeip.net> References: <48565E7A.50807@lc-words.com> <20080616085534.ca7524f8.wmoran@potentialtech.com> <20080616163856.H1467@wojtek.tensor.gdynia.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080616163856.H1467@wojtek.tensor.gdynia.pl> User-Agent: Mutt/1.5.18 (2008-05-17) X-Originating-IP: 83.253.25.183 X-Scan-Result: No virus found in message 1K8G6A-0001mb-4T. X-Scan-Signature: ch-smtp01.sth.basefarm.net 1K8G6A-0001mb-4T 10777fe4973c69d523724e96404845bd Cc: freebsd-questions@freebsd.org, Bill Moran , z.szalbot@lc-words.com Subject: Re: RAID 1 / disk error / Offline uncorrectable sectors X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Jun 2008 14:54:24 -0000 On Mon, Jun 16, 2008 at 04:41:15PM +0200, Wojciech Puchar wrote: > > > > Replace the hard drive. Every modern hard drive keeps extra space available > > to "remap" bad sectors. This happens magically behind the scenes without > > you ever knowing about it. Once you've hit "uncorrectable" errors, it means > > no. usually it means that there was an error when writing that sector, and > later there is an error on read. madia may be good (quite often is). > > if you would be right i wouldn't have my disk running one year after > having whole block of "uncorrectable errors" > > i just rewrote that blocks and they are readable. > > drive HAS TO know about bad media to remap, and no HDDs today perform > verification Also, remapping can only happen if the error is encountered on a write operation. If there is an error on read the drive cannot remap, since it does not know what data should be there. (A good RAID implementation could however handle a read error by reading the corresponding sector from the other disks(s) in the array and write it back to the failing disk, probably causing it to remap the block.) (Write errors is however usually a strong indication that the drive should be replaced ASAP.) -- Erik Trulsson ertr1013@student.uu.se