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Date: Fri, 22 Aug 2003 16:58:26 -0600
From: "Justin T. Gibbs" <gibbs@scsiguy.com>
To: Don Bowman <don@sandvine.com>,
	"'freebsd-scsi@freebsd.org'" <freebsd-scsi@freebsd.org>
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Subject: Re: Unrecovered read error on scsi drive
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> I have a system which popped out this error after many [500?] hours
> of disk stress [swapping, dd]:
> 
> (da0:ahd0:0:0:0): READ(10). CDB: 28 0 0 c7 92 a0 0 0 28 0
> (da0:ahd0:0:0:0): MEDIUM ERROR info:c792bb asc:11,0
> (da0:ahd0:0:0:0): Unrecovered read error field replaceable unit: e4
> sks:80,86
> 
> However, it claims to have 0 defects:
> 
># camcontrol defects 0:0:0 -f phys -G
> Got 0 defects.
> 
> How can this be? Are there other causes for this unrecovered read error?

The defect will only be recorded once the sector is remapped.  The
sector will only be remapped once either:

1) A read of the sector completes without errors so that the *correct*
   data can written to a spare sector.

2) You write to the LBA mapped to the defective sector so that a
   remap can safely occur.

--
Justin