[linux-lvm] Converting my Root file system to LVM [lastquestion]

[Andreas Dilger]

Steve Wray writes:
> > If root is unmounted when /sbin/vgchange is called, will the system
> > use the ramdisk?   If so, how does it know to use it?   (I'm kinda
> > new to figuring out how ramdisks work, I just follow instructions
> > and they work!)
> 
> Hey thats a good point... maybe a halt-time ramdisk? :)

Actually, I posted a similar question to linux-kernel, but I think it was
lost in the noise.  Basically, it _is_ possible to have a "finitrd" for
just this situation (at least on 2.4).  You unmount all but root, set up
a ramfs, and pivot_root into the ramfs.  You can then unmount root (not
just a read-only remount), and properly shutdown LVM/RAID/etc.  Haven't
tried it myself, but it should work.

Note that LVM doesn't actually write anything to disk with "vgchange -an",
so there is no real need to do this.  

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert