partial dumps (was Re: Change default dumpdir to /usr/crash?)

[Dan Nelson]

In the last episode (May 03), Andrew Gallatin said:
> Brad Knowles writes:
> > At 7:55 AM -0700 2004/05/03, Steve Kargl wrote:
> > >  I would support the integration of the changes.  With dual
> > >  opteron systems capacities of 16 to 24 GB of memory, partial
> > >  dump goes from a "nice to have feature" to a "we need this
> > >  feature."
> > 
> > Hmm.  What about compressed dumps?  Or are we doing that already?
> 
> savecore -z  
>
> This would help with /var sizes, but you'd still need a dump device
> as large as physmem.

That's compressed vmcores :)  For compressed dumps, see
http://dan.allantgroup.com/FreeBSD/ .  It's more than a
proof-of-concept (I use it on multiple systems), but is not committable
as is (see comments at the top of the diff).  The ability to do
kmem-only sparse dumps would reduce the necessity of true compressed
dumps.

-- 
	Dan Nelson
	dnelson at allantgroup.com