SCSI Hard drive "MEDIUM ERROR"

[Dan Nelson]

In the last episode (Nov 23), Nikolas Britton said:
> Is this the norm SCSI drives?... With IDE drives bad sector remapping
> is transparent, the drive does all that by itself, and if you start
> getting bad sectors it's because the drive ran out of spares

Remapping on an uncorrectable read error is usually not a good idea,
because that means your first read to that block will return an error,
and the 2nd time the kernel tries, it will succeed (because the block
has been remapped) but return garbage.  That's a very bad thing to do
:)  So remapping is only done on a write or on a read where the data
was recovered using ECC.  I would expect ATA drives to do the same.

One nice tool to install is ports/sysutils/smartmontools, which will
monitor the error counters kept by the drive and let you know if it's
going bad.  Works on both SCSI and ATA disks.

-- 
	Dan Nelson
	dnelson at allantgroup.com