[Info-vax] Not getting a dump file when VMS crashes

[Paul Sture]

On Tue, 03 Apr 2012 07:52:15 -0700, abrsvc wrote:

> On Tuesday, April 3, 2012 10:18:57 AM UTC-4, Rich Jordan wrote:
>> On Apr 2, 7:36 pm, David Froble <da... at tsoft-inc.com> wrote:
>> > JF Mezei wrote:
>> > > David Froble wrote:
>> >
>> > >> $ ana/crash
>> > >> _Dump File: sys$system:sysdump.dmp
>> >
>> > > Don't you have to specify a dump file specification in SYSGEN  and
>> > > a flag to cause VMS to dump to it ?
>> >
>> > Unless I've forgotten everything I've ever known (might not be much),
>> > the contents of memory are written by default to
>> > SYS$SYSTEM:SYSDUMP.DMP.  I'm not trying to write the dump to the
>> > paging file, or DOSD (off system disk) or anything like that.  My
>> > SYSDUMP.DMP is the size of physical memory.
>> 
>> Also going from memory since its years since I tuned a VAX, but should
>> not SYSDUMP.DMP be larger than actual memory by some increment when
>> you're doing a full dump?  I don't think it was a big increment but it
>> was there.
>> 
>> Ditto on the checking the fragmentation of the dump file; contiguous is
>> best; we worked on (way back) a system that had run for two years
>> straight and had its pagefile extended in chunks and a new CBT dumpfile
>> made that ended up being in 20+ fragments that could not get a valid
>> full dump (but did succeed with a selective dump).
>> 
>> Perhaps worth trying DUMPSTYLE=1 (or 3) and see if a selective dump
>> succeeds and gives the info you need.
> 
> The dump file needs top be a little larger than mamory to allow for the
> errlog buffers.  I seem to recall the difference being around 100 blocks
> or so.
> 
> A selective dump should succeed as the most important info is saved
> first.  The dump file might be incomplete, but there should be enough
> info to get an idea of the crash cause.
> 

Here's what I get with 128 MB RAM and DUMPSTYLE=0. VAX/VMS V7.3:

ERRORLOG.DMP;1          2049/2052      6-JAN-2007 19:40:17.74
SYSDUMP.DMP;3         262153/262161   28-MAR-2012 22:35:38.59


$ d=262153/2048
$ sh sym d
  D = 128   Hex = 00000080  Octal = 00000000200
$ d=262153 - (128*2048)
$ sh sym d
  D = 9   Hex = 00000009  Octal = 00000000011

I.e. 9 blocks added.

Reset to DUMPSTYLE=1

SYSDUMP.DMP;4         129652/129654    3-APR-2012 18:52:22.50

-- 
Paul Sture