Date: Mon, 16 Jun 2008 16:54:20 +0200 From: Erik Trulsson <ertr1013@student.uu.se> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Cc: freebsd-questions@freebsd.org, Bill Moran <wmoran@potentialtech.com>, z.szalbot@lc-words.com Subject: Re: RAID 1 / disk error / Offline uncorrectable sectors Message-ID: <20080616145420.GA26679@owl.midgard.homeip.net> In-Reply-To: <20080616163856.H1467@wojtek.tensor.gdynia.pl> References: <48565E7A.50807@lc-words.com> <20080616085534.ca7524f8.wmoran@potentialtech.com> <20080616163856.H1467@wojtek.tensor.gdynia.pl>
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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.) -- <Insert your favourite quote here.> Erik Trulsson ertr1013@student.uu.se
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