Dual booting: Ubuntu LTS and openSUSE 12.1

[Pongo A. Pan]

On Mon, 2011-11-28 at 06:00 -0500, LinuxIsOne wrote:
> On Sun, Nov 27, 2011 at 12:26 PM, Pongo A. Pan <pongo_pan at fastmail.us> wrote:
> 

> > Any number of distros can share the same swap space and it is easy to
> > have a large common data space and small home partitions with common
> > stuff like Music, Documents, and Downloads connected with symlinks.
> > I've currently got Ubuntu, Mint, Sabayon and openSUSE on this machine,
> > all sharing the same swap and data.  If I can do it, it's not hard.
> 
> Hi,
> 
> Can you tell me all the steps how to do? Like from the starting like
> making this /dev/sda1 and then for /dev/sda2...etc...etc... from each
> step exactly as you did, I would try to do in my PC. It supports 64
> bit processor.
> 
Returned to the list as this is clearly on-topic.  Please don't send me
private emails.

Partitioning is a big subject and the best way to learn about it is to
play around with Patrick Verner's Parted Magic (FOSS from
www.partedmagic.com) on a test-bed computer. 

I made my current testing setup with a 1 TB and a 500 GB hard disk with
all of the 1 TB disk in an extended partition, divided into several
virtual partitions for data, encrypted data,
compressed-old-data-I'll-likely-never-need-again, etc..  The 500 GB disk
has a primary partition for swap and the rest is an extended partition
with four virtual partitions for the four distros I'm currently
evaluating, four fairly small /home partitions, and a comfortably large
partition for /tmp which is shared among them.  I find it is easier to
do this before I install anything; the partitioning utilities which come
with installers vary in quality and understandability; Partition Magic
is easy and terrific.

I made descriptive labels for each partition.  This helps when
modifying /etc/fstab.  All of this is super easy with Parted Magic.  It
helps to have a printed list of your partitions when working: "parted
--list > parts.list" makes a file you can print out.

Then I installed the distros, being careful to assign *everything* to a
mount point: e.g., when installing Ubuntu, I assigned the root
directories of Sabayon, SUSE, and Mint to mount points
like /sabsys, /susesys and /mintsys and the corresponding homes to mount
points like /sabhome, /susehome, and /minthome.  This way the roots and
homes of each are available to all of the others. I share a /tmp without
apparent problems.  I also assign mount points to my various /data
partitions on the 1TB disk.  To avoid having to mess with fstab, prevent
each installation from re-formatting its / partition as this changes the
UUID!

Distros using grub 2 find each other and co-exist happily.  As it
happens, I installed openSUSE last in this case and simply told it to
use no boot loader at all and then ran update-grub from Ubuntu later to
add it to the boot menu.  I use the grub version from Ubuntu in the boot
tracks of the first hard disk since right now it seems to work the best:
"grub-install /dev/sda" will do it.

The rest is easy: remove directories like Music, Documents and .mozilla
from the /home/yourname folder and symlink them to the correspondingly
named directories in your common data partition for each distro.
Something like "ln -s /data/.mozilla" does it.  You can use the same
log-on name and UID for each distro without conflicts.  Be aware though
that some distros still start UIDs at 500 not 1000 (looking at you,
Fedora), so watch for this.

At some point you may want to change the setup.  This means you will
have to learn the fine points of modifying fstab in each distro and
using the blkid program to get the UUIDs for partitions. 

There are other ways to do this, probably better and more elegant ways,
but this works for me.  Needless to say, this is not a computer I do
anything vital on.  Happily, I've perfected my utility of futility to
the point that I'm not expected to do anything important anyway.

-- 
pongo pan
Mon, 28 Nov 2011 08:32:05 -0800
Aurelius up 17:27, 1 user, load average: 0.00, 0.03, 0.05
Linux 3.0.0-13-generic
Ubuntu 11.10, unity 4.24.0