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From: izumi@fugitive.berkeley.edu (Izumi Ohzawa)
Newsgroups: comp.sys.next
Subject: Access to OD ECC statistics??
Message-ID: <1990Dec11.232841.9991@agate.berkeley.edu>
Date: 11 Dec 90 23:28:41 GMT
Sender: usenet@agate.berkeley.edu (USENET Administrator)
Organization: University of California, Berkeley
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Is there any way to obtain error correction statistics on
read/writes for optical disks?

All the postings on B-land cubes and cooling fan blowing the
wrong way got me thinking about  it.

Perhaps, if we could track the error rate for an optical media
over time, we could get some idea on whether the laser optics
on the drive is accumulating too much dust and requires the
cleaning.

Someone actually posted cleaning devices for the media, and drive,
available from NeXT, but is the drive cleaner actually safe?
It can't be good to clean the optics too frequently, if the optics
is clean and OK.  On the other hand, you don't want to wait until
you lose some data from your OD.
I have not lost any OD myself, but I don't feel secure about
the state of write operations to the disk, not knowing how
much dust could have accumuated inside optical read/write head.
Imagine about marginal writes  which could occur (unknowingly to you)
because of reduce laser power --> lower temperature rise above the
Curie point.  The disk may become unreadable even on perfectly clean
drive if written on a marginal drive.

It seems that the system software should be able to monitor
error statistics on each media, and give some warnings on
the possibility of too much dust on optical drive optics.

The system kernel or the optical storage processor must be
keeping something on ECC error rate, and I would like to see
how my drives are operating.

Does anybody know how??

Izumi Ohzawa, izumi@violet.berkeley.edu