UDA50 problems

[Stan Tazuma]

Configuration:
	VAX 11/750
	4.1bsd Unix
	1 UDA50 disk controller, 2 RA81's
	TU78 tape controller with 2 slaves

Problem messages:
	uda0: soft error, disk transfer error, unit 1
	uda0: soft error, SDI error, unit 1, event 0353

	uda0: soft error, disk transfer error, unit 0
	uda0: soft error, SDI error, unit 0, event 0353

    The SDI error message is always paired with the disk
    transfer error message.
    Notice no sector numbers.  The messages occur sometimes 3
    hours apart, sometimes 24 hours apart, but usually not in
    bunches.  Typically, only 2-6 occur per day on a fairly
    active system.

Other:
	Out of 3 identical installations, we get these error
	messages on only one.  The system doesn't crash when
	these messages occur, but peculiar things happen (like
	the autoboot sequence pausing (until a key is hit)
	just before /etc/rc is run (no, we don't have rc prompt
	for anything)).

Anybody have experiences with these errors?
We have had DEC field service on this for weeks (months?),
and they don't seem to know what to do.  We have no manuals on
the UDA50 (the computers are installed at customer sites),
so if anybody out there does, maybe telling us what
event 0353 is would be of some help(?)

Thanks in advance.