Error in messages.

Malcolm Kay malcolm.kay at
Fri Feb 6 04:27:41 PST 2004

On Thu, 5 Feb 2004 18:58, Derrick MacPherson wrote:
> I started seeing this today:
> Feb  4 07:00:00 mail /kernel: (da1:ahc0:0:2:0): READ(10). CDB: 28 0 2 c 1
> 5f 0 0 10 0
> Feb  4 07:00:00 mail /kernel: (da1:ahc0:0:2:0): MEDIUM ERROR info:20c0168
> asc:11,0
> Feb  4 07:00:00 mail /kernel: (da1:ahc0:0:2:0): Unrecovered read error
> sks:80,35
> I umounted the disk, dumped it's contents to a spare disk.
> Can you suggest some tests for this drive, or should I just get it
> replaced?

Manufacturers often provide downloadable software for evaluating the state of
their drives. But you'll probably need an MS OS to run it. But it is pretty certain 
that you have a corrupt sector which is probably not repairable. The software
might allow you to encourage the drive to remap this sector to a spare.

An odd error report in normal operation might indicate just another random sector
failure and there are many; but most are repeatedly read until a valid read is 
obtained and then an alternate sector is mapped in its place by the software/hardware
in the drive itself. Frequently however the first reported error is an indicator of a failing
drive. Test software can tell you the current state of the drive but is unlikely to be
a safe indicator for the early occurence of further failures.

Your best approach would depend on the value you put on the future integrity of
the drive. If you were told that there was a 20% chance that your drive would 
deteriorate rapidly would you be prepared to trust your data to it, for the 80%
chance that it will be OK.

The 20/80% figures are of course just plucked out of the air - they may or may not be 
realistic in your case. My guess would be that if the drive ihas been in service for
a few years the probability that it has reach its end of life is higher than 20%.

Only in the case of a quite new drive that has shown no other signs of weakness would
I possibly rate at less than 20%.

Then how much is your time worth to spend it on exhaustive testing. Drives are really
rather cheap.

I guess even for home use I would dump it without investing any more time.


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