Date: Wed, 27 Feb 2008 19:20:56 +0000 From: Alex Zbyslaw <xfb52@dial.pipex.com> To: Stephen Hurd <shurd@sasktel.net> Cc: freebsd-stable@freebsd.org Subject: Re: ad0 READ_DMA TIMEOUT errors on install of 7.0-RELEASE Message-ID: <47C5B818.9090103@dial.pipex.com> In-Reply-To: <47C5ACD0.8000009@sasktel.net> References: <47C52948.2070500@sasktel.net> <20080227121129.GA76419@eos.sc1.parodius.com> <47C5ACD0.8000009@sasktel.net>
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Stephen Hurd wrote: > Jeremy Chadwick wrote: > >>> SMART Attributes Data Structure revision number: 16 >>> Vendor Specific SMART Attributes with Thresholds: >>> ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE >>> UPDATED WHEN_FAILED RAW_VALUE >>> 5 Reallocated_Sector_Ct 0x0033 253 253 063 Pre-fail >>> Always - 4 >> >> This shows you've had 4 reallocated sectors, meaning your disk does in >> fact have bad blocks. In 90% of the cases out there, bad blocks >> continue to "grow" over time, due to whatever reason (I remember reading >> an article explaining it, but I can't for the life of me find the URL). > > > This is unusual now? I've always "known" that a small number of bad > blocks is normal. Time to readjust my knowledge again? I have bought disks where the value of Reallocated_Sector_Ct was not 0, at least by the time I looked at it with smartctl. Nothing bad has happened to those disks in several years (hope that's not tempting fate). I have always assumed that what matters is when this value *changes*. If it's not changing, who cares? smartd will monitor disks and email you when certain attributes change (e.g. Pre-fail attributes like Reallocated_Sector_Ct). If it changed, it would mean that an attempt to write data had failed and that reallocation had happened. e.g. from smartd.conf /dev/ad4 -o on -S on -a -m root -M daily If your Current_Pending_Sector were non-zero you'd be in trouble, I believe. 0.02, pinch of salt, not an expert, slippery when hot, long time since I read the specs, etc etc. --Alex
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