[Info-vax] Unpleasant Disk Shadowing Surprise

[Kenneth Fairfield]

You don't say what your storage configuration is.
Are the shadow members both internal disks in the
DS10, or are they on an external controller?

Reason I ask is that several years ago, on some
HSJ-hosted storage (IIRC, otherwise it could have
been on HSGs), one disk in a shadow set started 
logging a large number of errors, on the order of
several hundred per minute.  Unfortunately, the
controller went to heroic efforts to recover!

As a result, the shadow set was functionally
inaccessible. (Well, it was a bit more complicated
than that as I think we first tried copying in
a 3rd member per our standard procedures, but
that only made the problem worse.)

In the end, we had to just yank the bad disk out.
The controller was determined *not* to drop the
bad member.

So...  What do you system error logs show for the
bad disk?  What was the error count on that member
before it was dropped?

With the HSJs, I think Compaq determined there was
some setting that we could apply that would keep
the controller from working so hard to recover.
Without knowing your storage configuration, there's
no way to say whether something similar applies.

However, watching disk error counts is *very* 
important in all cases.

    -Ken