A New FreeBSD Server

[Ed Maste]

On Mon, Jun 26, 2006 at 10:10:28AM -0400, Mike Meyer wrote:

> In <20060626111208.P77513 at woozle.rinet.ru>, Dmitry Morozovsky <marck at rinet.ru> typed:
> > On Sat, 24 Jun 2006, Mike Meyer wrote:
> > MM> The other constraint on swap is that if you want the system to save a
> > MM> core dump if it panics, you need a device to dump on that's 64Kb
> > MM> bigger than ram. That's one device, not all of swap.
> > This is not quite true, as there always are some unused memory regions, hence 
> > you need not add 64k to RAM size. At least, I had no trouble using swap == RAM 
> > for last 5 years or so...
> 
> Or memory areas that aren't needed when doing the post mortem. The
> question is, how do you guarantee that those are what's not going to
> make it out to the dump device?

The core dump routine won't even attempt to write if the swap space is too
small, so there's no ambiguity as to what makes it into the core file.

FreeBSD 5.x and previous try to write all of memory out so the extra 64Kb
or so is necessary.  Also, -CURRENT uses "minidumps" on i386 and amd64, so
only memory regions of use are written out and you can get by with swap
smaller than RAM.

-ed