Re: current best practice for booting >2TiB volumes?

[David Laight <david%l8s.co.uk@localhost>]

On Fri, Feb 18, 2011 at 06:28:34PM -0500, Matthew Mondor wrote:
> On Fri, 18 Feb 2011 12:09:39 -0600
> eric%cirr.com@localhost (Eric Schnoebelen) wrote:
> 
> > When I attempt to boot (after relocating wd2/3 to wd0/1), the gpt
> > mbr loads bootxx_ffsv1, but bootxx_ffsv1 complains it can't find
> > /boot in the root filesystem.

The bootxx code probably requires that to root fs be at the start of
the raid volume.
It might also get confused by any disklabel in the pbr (presumably
you don't have one).
Certainly 'boot from RF' relied on the bootxx code adding in 64 sectors
and trying again after an initial file open failed.
But I can't remember if this was in any way related to detecting
an RF entry in the pbr's disklabel.

Your disks may have larger physical sectors. So you really want to
align the fs fragments/blocks onto physical sectors. The offset 63 sector
offset (one nominal track) isn't a good value!

> Is your FS really an FFSv1 one?  Otherwise you will probably want to
> install the bootxx_ffsv2 loader instead.  FFSv2 supports larger file
> systems than FFSv1, but of course that might not be a problem for
> your / ...
> -- 

Actually FFSv1 supports  disks with more than 2^32 sectors - you just
have to increase the fragment size so that there are less than 2^32
(or maybe 2^31) fragments.

FFSv2 newfs runs faster (because it does lazy initialisation of on-disk
inodes, but all the metadata doubles in size.

        David

-- 
David Laight: david%l8s.co.uk@localhost