If one is re-installing a machine (not upgrading) it is not obvious
(if possible) to specify that partitions shoudl be added to fstab but
they take no part in the RH install (e.g. user home directories, private
(ssh) keys etc).

Clearly one can add them into fstab in the postinstall, but if they are on
the same disk as /,/usr (etc) it seems hard to leave those bits of the
partition table alone.

In JumpStart, one may specify "preserve" after a partition definition to
specify that it should be left intact.  In the Sun model this means that
all partitions need to remain as they did before (just leaving the
preserved ones where they are ought to be sufficient).

I tried following the partition logic in the python but got lost trying to
follow the class/object stuff from kickstart.py (It does say it is magic).

This is true in 6.1 (etc) as well but clearly work is being done here as
--ondisk was added recently...

[ This reminds me, why no pre-install script? ]

 -- Jon