Multiple installations

[Tim Writer]

"Keith Mastin" <kmastin-PzQIwG9Jn9VAFePFGvp55w at public.gmane.org> writes:

> > When it comes to PC hardware, I really don't, therefore I have what's
> > probably a ridiculous question.
> >
> > I set up a machine with a single hard drive partitioned to dual-boot
> > between NT Workstation and SuSE Linux.  I use my current Linux
> > installation for all kinds of volatile stuff: trying out various SW
> > packages, my own development projects....  I would like to have a
> > second, bootable Linux environment on that computer that would stay
> > relatively clean as a "production" server where I could demo stuff to
> > clients without wondering what my latest downloads mangled.
> >
> > I've done this on Macs where it's as simple as adding another drive,
> > installing a second copy of the system, and choosing which
> > volume/partition to boot from.  With PCs, however, I've heard horror
> > stories from others about failing to boot because of number, location,
> > or size of a given partition...or master vs. slave drives.  Are there
> > warnings/guidelines for what I want to do?  (It sounds like it should
> > be a "just do it", but others' experiences make me nervous.)
> 
> Just do it. If there are problems they are workable. I would trust
> linux/xBSD for this long before I would trust M$. You can share
> filesystems between the installations. Windoh$ wants to be on the first
> filesystem of the primary drive, linux really has no limitations in
> comparison.

Linux doesn't (care much about where it is) but some of the BSDs do.
FreeBSD, for example, requires a primary partition which it slices in its own
way (similar to logical partitions within an extended partition).  Linux has
support for FreeBSD slices but you have to be careful about layout as it
(Linux) treats the slices as extended partitions.  Consequently, installing
FreeBSD in the wrong location on your disk can result in renumbering your
Linux partitions.

A good organization for triple booting Windows, Linux, and FreeBSD on one
disk is:

    /dev/hda1   Windows
    /dev/hda2   extended
    /dev/hda3   FreeBSD (containing FreeBSD slices)
    /dev/hda4   unused
    /dev/hda5   Linux
    /dev/hda6   Linux
    ...
    /dev/hdaN   Linux

where hda5 through hdaN are your separate Linux partitions (e.g. /, swap,
/var, /usr, and so on).  In Linux, your M FreeBSD slices will be accessible
as /dev/hdaN+1 through /dev/hdaN+M.  Sometimes (e.g with older BIOSES that
can't boot from a cylinder larger than 1024), it's advantageous to have a
separate (small) /boot partition at the beginning of your disk, like this:
    
    /dev/hda1   /boot
    /dev/hda2   Windows
    /dev/hda3   extended
    /dev/hda4   FreeBSD (containing FreeBSD slices)
    /dev/hda5   Linux
    /dev/hda6   Linux
    ...
    /dev/hdaN   Linux

Note the placement of the extended partition (containg logical partitions
used by Linux) before the FreeBSD partition.  If the order was reversed,
you'd have this arrangement:

    /dev/hda1   /boot
    /dev/hda2   Windows
    /dev/hda3   FreeBSD (containing FreeBSD slices, e.g. hda5, hda6, ... hdaM)
    /dev/hda4   extended
    /dev/hdaM+1 Linux
    /dev/hdaM+2 Linux
    ...
    /dev/hdaM+N Linux

This can work but if you remove FreeBSD or simply boot Linux with a kernel
w/o support for FreeBSD slices (such as a rescue kernel), your Linux
partitions will be renumbered (starting from hda5 again).  Needless to say,
this can cause a lot of problems.

-- 
tim writer <tim-s/rLXaiAEBtBDgjK7y7TUQ at public.gmane.org>                                  starnix inc.
tollfree: 1-87-pro-linux                        thornhill, ontario, canada
http://www.starnix.com              professional linux services & products
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