EXABYTE TAPE DRIVES

[The Management]

I have been using 2 Exabyte tape shoeboxen on a 3/50 to backup my sun farm
(via rdump) for almost a year.  Lately I have been having two different
problems, which I would like to submit for public comment (please copy me
directly via email as it has been about 6mo since I had any time to browse
through sunspots... :-( )

PROBLEM 1

st1:  failed cmd =  8  0  0  c8  0  0  
st1 error:  sense key(0x3): media error
           sense = 70  0  3  0  0  0  0  12  0  0  0  0  0  0  0  0  0  25  
		   af  10  20  0  0  1f  5d  e0  0  0

This "media error" is not always reproducible;  sometimes if you cycle
power on the tape transport and start over you can read the volume;
sometimes it occurs simultaneously with another error condition on the
other drive on the same controller (huh?); it is often followed by an I/O
request timeout, as if the driver forgets to reset the I/O request timer,
followed by a "can't find unit" message and other ugliness.  It happens
both on read and write operations;  generally on a write operation I
associate it with both tape drives writing dump tapes at the same time,
but that is the very roughest empirical hunch. One condition under which
it occurs is...

PROBLEM 2

When it all began, last summer, I could read&write tar and dump tapes on
both drives interchangeably, No Problem.  Recently I have noticed (to my
dismay) that dump tapes written on st0 cannot be read on st1 (maybe vice
versa also, I have not yet checked)...  is this a known problem with
Exabyte transports, that some kind of skew or other adjustment begins to
drift so that two drives are no longer interoperable?  If so, is the
adjustment difficult?  Can a fairly careful reasoning being with a scope
and patience do it, or is this a "don't try this at home, kids" kind of
thing?

That's it.  Before I spend hours trying to diagnose this very annoying
apparently compound problem, I would like to hear about any wheels already
invented and rolling.   The world wants to know...

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