Subject: Re: savecore_flags="-z"
To: None <tech-kern@netbsd.org>
From: Greg A. Woods <woods@most.weird.com>
List: tech-kern
Date: 12/02/1999 20:24:34
[ On Thursday, December 2, 1999 at 14:49:25 (-0500), Andrew Brown wrote: ]
> Subject: Re: savecore_flags="-z"
>
> hmm...but then you could just leave the dump in the dump partition,
> right?  i mean...with 4gb ram, when are you *ever* going to swap?  :)

When I do need swap space then I want it to be striped over several
spindles (either in "hardware", or with multiple swap partitions), and
it really doesn't matter how much real RAM I've got.

However if I do have 4GB of RAM and I do want to handle full crash dumps
I'd be reluctant to put all that 4GB of swap/dump space on one spindle.

This suggests to me that a crash dump should be able to sequentially
write to all of the active swap/dump partitions.  Can it do this now?

As for using "savecore -z", well I do think that it makes the most sense
to compress crash dumps when saving them on the filesystem.  I would
also suggest that anyone who needs to frequently analyzed their own
crash dumps should specify a dump partition separate from their swap
space and always read the dump directly off the raw disk (I'm assuming
here of course that gdb won't have any trouble doing this -- I've never
tried it myself in real life :-).

The other interesting question is whether or not the dump should be
compressed while it is being written to the dump partition during the
crash if indeed there's not enough space to store it all....

-- 
							Greg A. Woods

+1 416 218-0098      VE3TCP      <gwoods@acm.org>      <robohack!woods>
Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>