summary f77 bus error

From: Jim McCormick <jwm_at_dec3.mc.duke.edu>
Date: Fri, 12 May 1995 16:43:37 -0400

summary f77 bus error
Problem description:

We are having a problem with a large fortran 77 program running
on a dec 3000/800. We are running osf1 ver 2

The system has 832 MB of ram and swap space is 1082 MB. I realize
this is very little swap for the amount of ram we have.

The actual fortran program is about 500MB in size. It reads and
writes large files (400-500MB) and also does numerical processing.

The program often crashes with a "bus error". We also get an error
on the operators console "vm_swap I/O error during pagin".
The error occurs both during IO and also during numerical processing,
after IO is completed.

What exactly is a bus error?

How does IO allocate memory such that the free pages go to zero? Is data
double-buffered.

Is the problem that we are just running out of virtual memory? I
don't want ot reformat the disk if this is not the problem.

Results:

A bus error is the same as an "access violation" on a VAX/VMS system. It basically
means that somewhere in your program one is attempting to write beyond the allocated
boundary of an array clobbering other data.

The vm_swap I/O error may indicate a hardware problem. As recommended uerf was
checked and there were numerous cam scsi errors so it looks like a hardware
problem with the disk.

I wish to thank everyone who responded.

                                                Jim McCormick
Received on Fri May 12 1995 - 16:44:41 NZST

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