Redoing LVM/partition geometry from rescue mode losslessly?

[Paul Howarth]

On Fri, 2006-05-19 at 02:44 -0400, Tony Nelson wrote:
> At 11:16 AM +0100 5/18/06, Paul Howarth wrote:
> >Philip Prindeville wrote:
> >> Hi.
> >>
> >> I kickstarted a computer with the following:
> >>
> >> #clearpart --linux --drives=hdd
> >> #part /boot --fstype ext3 --size=100 --asprimary
> >> #part pv.15 --size=29957 --asprimary
> >> #part pv.9 --size=8092 --asprimary
> >> #volgroup VolGroup00 --pesize=32768 pv.9
> >> #volgroup VolGroup01 --pesize=32768 pv.15
> >> #logvol swap --fstype swap --name=LogVol01 --vgname=VolGroup00 --size=1024
> >> #logvol /home --fstype ext3 --name=LogVol00 --vgname=VolGroup01 --size=29920
> >> #logvol / --fstype ext3 --name=LogVol00 --vgname=VolGroup00 --size=7008
> >>
> >> only to find out from the user that they needed more root space, but didn't
> >> realize it at the time.  They now want to grow their root by 2GB.
> >>
> >> Is there a relatively painless/foolproof way to do this, say rebooting
> >> in rescue mode, and resizing?
> >>
> >> The user doesn't want to machine dumped/restored, or reimaged (because it's
> >> now been customized).
> >
> >Where is this extras space going to come from? You can't easily get it
> >by reducing /home because for some reason you put that on a different
> >volume group.
> 
> It does seem an odd setup.  Probably the solution lies not so much in LVM2
> as in mount, and moving some part of / to another partition, say /tmp or
> /usr or /usr/local.  The space could come from reducing /home.

Or by carefully selecting some directory in the root filesystem that
takes up lots of space, moving it to somewhere under /home and adding a
symlink from the old location to the new location (the sort of thing I
had to fairly regularly when disk space wasn't so cheap and LVM wasn't
around). The selection of directory does have to be very carefully made
though, as some directories *need* to be on the root partition
(e.g. /etc, /bin, /sbin, /lib) or the system won't boot. /var is
probably a good choice in this case.

Paul.