🚀 go-pugleaf

In article <1992Nov7.153607.205@gamelan> thf@zelator.in-berlin.de (Thomas Funke) writes:
>I got the following message when I was writing a file on a OD:
>Nov  6 20:16:09 gamelan mach: od0?: write failed (ECC) block 246880 phys block
>246880 (19579:0:0)
>Nov  6 20:17:24 gamelan last message repeated 2 times
>Nov  6 20:17:58 gamelan mach: od0?: write failed (ECC) block 246880 phys block
>246882 (19579:0:2)
>
>But the file was correct, thus I could read it back perfectly. Is this  
>something I have to worry about ?
>

What most probably happened was due to either dust on the OD platter or
lens, the OD was not able to write to a block and failed, issuing the
error messages. Subsequent to the write failure, the OD circuitry did
a block remapping and wrote the data to a clean block somewhere else on
the disk.

You might be worried for two reasons: 1) Your OD drive might be failing
which is due to the write failures, are you experiencing other problems
with the drive such as irregular sounds? If so, worry about whether your
drive is still under warranty.

2) You might worry that your OD disk itself is going bad. Check it for
dust and follow standard CD practise when cleaning it (be VERY gentle,
it is extremely easy to scratch). I would check for the number of alternate
blocks you still have left to remap onto. Do this by logging in as root
and running:

shaman# disk -s /dev/rod0a
disk name: Canon OMD-1
disk type: removable_rw_optical
disk statistics:
              1 average ECC corrections per transfer
              2 maximum ECC corrections per transfer
              4 verify retries
              1 verify failures
89/2512 ( 3.5%) alternate blocks used


Check the last line. If it gets close to 80%, then copy all of the
data on the OD onto another OD or your hard drive, then reformat
the OD. Run disk again, make sure the # of alternate blocks is
back down to 10% or so (or else your OD is permanently bad, throw
it out) and recopy your stuff onto it.


 - Jiro Nakamura
   Technical Editor / NeXTwatch


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Jiro Nakamura				jiro@shaman.com (NeXTmail)
NeXTwatch / Technical Editor		76711,542 (CIS)
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