zfs booting feedback

[Kurt Lidl]

On Thu, Jul 12, 2012 at 12:48:40AM -0400, Chris Ross wrote:
> 
> On Jul 11, 2012, at 23:59 , Kurt Lidl wrote:
> >>  I'm looking forward to experimenting with FreeBSD sparc64, and zfs.
> >> I'm a zfs newbie.  :-)
> > 
> > I put the iso I built, along with a checksum file for it, and the script
> > that I used for installing all the bit here:
> > 
> > 	http://www.pix.net/ftp/pub/freebsd/
> > 
> > You might want to fiddle with the size of the ZFS partition that the
> > script creates.  I have Sun "18GB" drives, so I just told it use 12GB
> > as ZFS, and the rest as swap.
> 
>   Thanks.  I read that there was an issue with freebsd swap vs. ZFS swap
> for FreeBSD dumping.  Looking at your script, it looks like you're using the
> "freebsd-swap" which will allow for crash dumps.  But, not being familiar
> with gmirror and what you've done with "gswap", I just wanted to confirm.

Yes.  As I understand it, freebsd doesn't deal with swapping to a
zfs volume reliably -- ultimately it will deadlock.  And it cannot
crash dump to a zfs volume at all.  So, yes, I have a geom mirror
setup between two vtoc partitions on the sparc64, and use that as
the swap/crash dump space.  That's the reason for the (geom) mirrored
swap partition.  The name "gswap" is just to remind me that's it's
a geom mirror -- the choice of name is really arbitrary.

Sparc64 doesn't support minidump format either, as far as I know,
so you must have a swap space >= physical memory for it to work.
On amd64, minidump format crashes are supported, so only the active
kernel memory is dumped, and not all of physical memory.

>   I'll give it a go tomorrow!  Thanks much...

Good luck.

-Kurt