750 machine check 2

[Charles E. Perkins]

We have had many crashes on our VAX 11/750 system running UNIX 4.1bsd.
After a few times we got tired of calling DEC service out; they replaced
the same board several times and it has not seemed to improve things.

Is this a common problem?  Are there known reasons for this problem?
Is it somehow caused by software?  My current theory is that DEC
has some wierd problem that shows up under UNIX but not VMS.
If it was really a software problem, why does the Remote Diagnostic
Center always conclude otherwise (it invariable reports a problem
with the translation lookaside buffer, hence the board replacement).

I would certainly appreciate any comments you might have about this
(especially solutions or bug fixes!)  Even if your machine runs
perfectly, that is good information, because then I can tell DEC
that they need to get us some better hardware like other sites have.
(!)  Usually this seems to happen under moderately heavy use
which for us means a load average of over 4.  We have root and /usr
on a RA80, and the rest of our file systems on a RA81.

Thanks for your help.

Charles Perkins
Logic Design Systems

PS. Has anybody written a dump routine for UDA50 disks?