preserving partitions during reinstall

[Dave Mitchell]

On Tue, Sep 11, 2012 at 12:47:25AM +0200, Suvayu Ali wrote:
> On Mon, Sep 10, 2012 at 10:08:47PM +0100, Dave Mitchell wrote:
> > 
> > The point is that *none* of the Ananconda install options:
> >     Use all space
> >     Replace Existing Linux System(s)
> >     Shrink current system
> >     use Free space
> >     Create custom layout
> > will read the existing partitioning of vg_pigeon and present that to you
> > as a default; they all either suggest a completely new set of defaults, or
> > in the case of custom, present no defaults at all.
> > 
> > Or to put it another way, missing from that list of install options above,
> > seems to be:
> >     Keep existing Linux partitioning
> > 
> 
> You say your original partitioning was custom partitioning, then how do
> you expect Anaconda will figure it out without help?  The way to do what
> you want would be to enter custom partitioning, not delete any of the
> existing partitions, specify the appropriate mount points (again only
> you know this, no way Anaconda can figure this out), and then continue
> with your upgrade as usual.

Sigh.. Let me repeat myself again.

I expect an option within anaconda that will *inspect* the existing
partitioning layout of a device, and present that to me as the new
default. Anaconda has the ability to examine the vg_pigeon device, and
see that there are 3 partitions on it, last mounted as /, /home and swap.

*None* of the options, including custom, present me with the original
partition sizes. The best I could do in principle would be, before the
reinstall, to note the existing partition dimensions, then in anaconda,
manually create 3 partitions on the cg_pigeon device, not format the one
corresponding to /home, then hope and pray that when I specify /home as
being XXXMb, that anaconda treats this in the same way as before in terms
or rounding to nearest cylinder etc.

Or to come at the question from another angle:

I have a system with a reasonably straightforward layout:
1 disk, split into two physical partitions; the first holds /boot, the
2nd is an encrypted LVM volume that has 3 partitions: /, swap /home.
I want to install a new release of the OS (overwriting / and /boot), while
preserving /home. How can I do that in a simple and safe manner?

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