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I've hit some snags in the last two upgrades (which I've been able to resolve with time, patience and Ask Ubuntu :) so come 12.04 I'm considering a side-by-side installation. Perhaps even installing a pre-release before that (because virtual machine testing can't reveal hardware-related issues).

So, let's say I installed a side-by-side version. As far as I can tell this splits my existing partition and installs a brand new Ubuntu on partition 2. If all goes well, there are no hardware issues, and my favorite apps seem to be working, how do I switch to a one-sided installation? If I can't, how do I do a side-by-side installation the next time?

(And, am I crazy to consider using a pre-release version to do a side-by-side installation?)

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Yes, you're crazy. however, i've done it before, so you aren't that crazy. :P – James Nov 21 '11 at 17:38
up vote 4 down vote accepted

Can I suggest another approach? Keep the dual boot and share all your files with both systems.

Why? Because in 6 months you will have the same problem with 12.04 and 12.10.

Example 1

An example of what I want to suggest...

  1. OS1 (11.10): /, swap, /home. Total can be as low as 25 Gb.
  2. OS2 (12.04): /, swap and /home. Total can be as low as 25 Gb.
  3. OS1+OS2: data partition.

(25Gb: 10 for root, 5 for swap, 10 for home: it works because I symlink the directories in home to the data partition. That way I can have the same icons on my desktop for both systems but also when I reformat 1 of the 2 and reinstall another Ubuntu).

Example 2

A slightly different example if you're trying to save HDD space...

  1. OS1 (11.10): /, swap, /home. Total can be as low as 25 Gb.
  2. OS2 (12.04): /, swap. Total can be as low as 15 Gb.
  3. OS1+OS2: data partition.

Here you can mount the /home into OS2 (so just mounting not formatting when you setup your system) and use a different username for both OSes. That way you will not run into any conflicts and you can save a 10 Gb of every other OS you include (you can do this with more than 2 OSes and even SUSE, Redhat, CentOS etc ;) )

I am a big supporter of symlinking.

Example... say your data partition is named 'discworld'. Create all dirs that are now in /home/{user} in that partition...


rm all directories inside `/home/{user}' and then symlink them:

`ln -s /discworld/Desktop Desktop`
`ln -s /discworld/Downloads Downloads`

Put all users into 1 group and set discworld to that group: that way you have 1 desktop over the whole systems, all downloads go to 1 location etc etc.

Using the data partition

Either way, ALL interesting files you have go to the data partition. Use the current system (11.10) and keep updating the newest system (12.04). When the newest system (12.04) is up to your standard use that as the current system and use OS1 to install the newer newest release (ie. 12.10).

That way you can always fallback to your last stable Ubuntu.

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hi rinzwind, this makes a lot of sense! I've posted a follow-up question but feel free to add it to your answer if that makes more sense to you, and I'll delete the question… – d3vid Jan 25 '12 at 8:41
the space issue was more about creating partitions than the /home issue - I have multiple users, their /home folders are generally for config only and quite small - all data/media/stuff is kept in /home/data (there is no user named data) - I really want usernames to stay the same - so I think it'll be easiest for me to keep separate (small) /home folders in each OS partition and mount the data partition as /media/data or something - does that make sense? – d3vid Jan 25 '12 at 12:43
makes perfect sense! :) It's the way I normally do this (I prefer my /home to be dedicated to that OS too. – Rinzwind Jan 25 '12 at 12:47
a further complication - I actually have multiple data folders, /home/data1 and /home/data2 with different user rights managed by bindfs - would it be possible to replicate this with the data partition? gosh maybe this deserves another question too! – d3vid Jan 25 '12 at 12:49
/datapartion/data1/ /datapartion/data2/ ;) – Rinzwind Jan 25 '12 at 12:57

The easyest way to go from a dual-boot to a one boot configuration is to install everything again, formating your partition.

Thinking on the reverse process for installing ubuntu, the other way would involve configuring grub and working with gparted.

When you install another OS, in this case Ubuntu 12.04, side-by-side with ubuntu 11.10, your disk will be partitioned in order to make the two OS work indepently. So when you boot your computer grub will prompt you with the possible options.

If you choose 11.10, you will run only 11.10, if you choose 12.04 you will boot only 12.04 (Some BIOS on some computer have limitation on how many partitions it can handle, normally 4 is the top, so you are limited to have this number of OS in the same HD.)

So after you perform your tests and get the conclusion what do you want to run as standard, you could open gparted and delete partitions you do not want and put the space back to your old partition or make the configuration you need. Working with partitions is not that hard, but can be confusing and lead you to make mistakes that will make you loose everything, read a lot about it and plan your moves before you make them.

The second tasks is to change the grub configuration, this is easy and you can find all over the web how to manipulate, change and configure your grub, you will basically change a conf file and update grub. if you dont change it your grub screen will show the OS removed, but if you try it will give you an error.

If your intetntion is to be able to test and verify new verswions of Ubuntu and other OS, you could work with different HDs where you can make each HD an exclusive OS, if you have a computer that can startup from external HD, then it will be easyer then having to make lots of configurations and changes to go back where you were before your testing.

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thanks for the tips, especially pointing out that it can be as easy as just wiping the unwanted partition; I still have the issue of data storage, which I think Rinzwind's answer addresses – d3vid Jan 25 '12 at 12:54

It may be more headache than you want, but LVM was built for situations like this. Where you want to add or remove size to or from a partition whenever you like. It's not a super-easy gui procedure though, and can occasionally get buggy.

If volume groups, logical volume resizing, and command line aren't your cup of tea, this might not be the best idea.

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