Re: Geom Vinum backwards compatible?

Hi,

On Wed, Oct 13, 2004 at 05:18:20PM +0200, Stijn Hoop wrote:
> On Wed, Oct 13, 2004 at 06:10:41PM +0300, Marko Raiha wrote:
> > On Wed, Oct 13, 2004 at 12:28:22PM +0200, Lukas Ertl wrote:
> > > On Wed, 13 Oct 2004, Stijn Hoop wrote:
> > > >I haven't tried this with geom_vinum, but using the old vinum I could 
> > > >grow the BSD partition that contained my vinum "drive", then restart 
> > > >vinum which would recognize more free space on it's "drive" and then add 
> > > >another subdisk on that same drive. I've done this around a year ago, so 
> > > >this might not work exactly as described but it is possible.
> > > 
> > > That should work with geom_vinum as well, although I haven't tried yet.
> > 
> > Is it possible to grow vinumized BSD partition only from the end or also
> > from the beginning?
> 
> Seeing as vinum stores it's configuration data at the start of the
> vinum drive, I think it's not likely to work. You might get away with
> moving the data with dd, if you set your blocksize to sector size (or
> at least to a divisor of the spare space you allocate at the front). I
> wouldn't want to test this without good backups though, and at that
> point it might be easier to just recreate your vinum stuff from
> scratch and restoring anyway.
> 
> > > >Even more likely to work is just adding another BSD partition on your
> > > >bigger drive, add that as a new vinum drive and then add
> > > >subdisks/plexes on top.
> > > 
> > > That's the way to go, but just make sure you have only one vinum
> > > drive per disk.
> >
> > I have more than one vinum drive per disk and thats why I'm asking about
> > growing vinumized partition to get rid of other than one of them before
> > upgrading from 5.2.1 to 5.3.
> 
> Why is more than 1 vinum drive per disk not good?

I don't know details but I remember to have read about troubles with
gvinum and many vinum drives per disk. Tried to find some threads of it
but found only this:

    http://www.freebsd.org/cgi/getmsg.cgi?fetch=2027518+2030746+/usr/local/www/db/text/2004/freebsd-current/20040829.freebsd-current

Maybe Lukas Ertl knows more about this? Cause recommends to use only one
vinum drive per disk.

Regards,
-- 
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                |  Marko Räihä                                 |
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