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Second UBA/UDA50/RA81 questions

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Nov 7, 1986, 11:51:33 AM11/7/86
I have a 4.1 BSD UNIX system on a VAX 11/780. Recently we installed a
second UNIBUS and a UDA50 controller on that second UNIBUS, all by
itself. We figured that this way the UDA50 would not kill the activity
on the first UNIBUS. The UDA50 is connected to three RA81 disk

We are having a problem where we get a "uda0: disk transfer error"
followed by a bunch of soft errors and sometimes a hard error. The
RA81s have been reformated so it's not a bad block problem. When we
get the error the access light on the particular drive being accessed
goes out and the application that was doing the write to the RA81 disk
drive bombs out. So there are no reads or writes being done by an
application to the RA81 at this point. But a few seconds later the
RA81 access light comes back on and we get about the same error
sequence. Then the application is actually able to report its exit and
no more errors are printed - the RA81 is not being accessed any longer.

We are able to make a new file system ("mkfs"), mount the file system,
create a lost+found directory, dismount the file system, run "fsck",
and remount the file system with no problems. The above application
that was mentioned just keeps filling a given RA81 with 100K-long files
named x.0, x.1, x.2, etc. as a write test. This is nothing more
strenuous than a big disk-to-disk tar or dd would be. The errors come
up at seemingly random times and have occurred on all three disks.
Starting over from scratch on any given RA81 does not seem to matter -
the errors don't occur at the same time/place on the disk again.
Sometimes they occur earlier, sometimes later.

I have a single UNIBUS with a UDA50 and three RA81 disk drives on
another VAX 11/780 and I can run the same application with not a single
error. Both VAX computers use 4.1 BSD and have the same driver
software. In fact, the VAX where everything works has about 5 times
the number of users on it at any given time. All switches on the UDA50
boards on both VAXes are set exactly alike.


Has anyone ever seen such a problem? If so, what did you do about it?

Thank you.
Jon Eichelberger

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