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From: allbery@NCoast.ORG (Brandon S. Allbery KB8JRR/AA)
Newsgroups: comp.unix.sysv386
Subject: Re: Kernel core dumps (was Re: out of swap space??)
Message-ID: <1991May4.232044.3487@NCoast.ORG>
Date: 4 May 91 23:20:44 GMT
References: <450@bartal.BARTAL.COM> <9105031411.aa04050@art-sy.detroit.mi.us> <1991May04.132158.17121@turnkey.tcc.com>
Reply-To: allbery@ncoast.ORG (Brandon S. Allbery KB8JRR/AA)
Followup-To: comp.unix.sysv386
Organization: North Coast Public Access Un*x (ncoast)
Lines: 45

As quoted from <1991May04.132158.17121@turnkey.tcc.com> by jackv@turnkey.tcc.com (Jack F. Vogel):
+---------------
| >  At what point does the kernel begin using the swap area on the next boot??
| 
| Sometime before coming up fully multiuser a script is run, /etc/dumpsave,
| which decides if there is a dump in the swap area and prompts you if you
| want to save it. You can save either to floppy or tape. If you choose
| floppy you must have enough formatted floppies to hold it (the size will 
| be approximately your real memory size). If you choose not to save, the
| kernel will begin using the swap device and the data will be overwritten.
+---------------

On SCO, it's /etc/sysdump and it tells you to run /etc/ldsysdump to read the
dump into a file for analysis.  Otherwise, it's the same.

+---------------
| > It would have been handy to be able to run something as root that
| >forces a panic, then reboot and analyze the dump while the system is still
| >reasonably reliable.
|  
| Again, I can't speak for SCO's implementation, but one way to do this
| given the AT&T standard is to have the kernel debugger linked into your
| kernel (see debugger(8)) and then if you want to force a dump, enter
+---------------

Alternatively, if all you want to do is look at running kernel information
without playing any games with it, try "/etc/crash /dev/kmem".  You don't even
have to panic the system (but you *will* if you try to change things).

+---------------
| Just for comparison, no commercial plug really intended this is just for
| an implementation example, AIX on the PS/2 allows you to create a dedicated
| dump partition where multiple dumps can be stored. This allows you to take
+---------------

Look at the value of DUMPDEV in the kernel configuration of any V7, SIII, or
SV.  This is nothing at all new....  The default, of course, is the same as
the swap device; you can, if you wish, set up a separate device and use that.

++Brandon
-- 
Me: Brandon S. Allbery			  Ham: KB8JRR/AA  10m,6m,2m,220,440,1.2
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