Subject: Re: wedges and what does that mean?
To: Martin Husemann <martin@duskware.de>
From: David Laight <david@l8s.co.uk>
List: current-users
Date: 09/04/2006 20:49:13
On Mon, Sep 04, 2006 at 01:34:39PM +0200, Martin Husemann wrote:
> 
> But wedges have no inherent corelation to some on-disk partition format,
> like the disklabel which the old partition code used.

Unfortunately this sucks realtime....

There is nothing (to my knowledge) to ensure that the 'wedge numbers'
stay anything like consistent across reboots.
So add a 'partition' to an MBR disk, and when you reboot all the numbers
will change.

Your old /tmp partition that you 'newfs' on boot suddenly changes
identifier and something else gets clobbered [1].

NFS file handles (that are usually based on the disk device major/minor)
are likely to refer to a different filesystem...

I'm also not at all sure how the boot code is meant to locate the correct
root filesystem.

	David

[1] this can (and has) happened with the existing scheme, but it requires
that the kernel mis-order the disks (or a new kernel fail to detect all
of the disk controllers).

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