How does the installer decide

[Bret Busby]

On 04/05/2021, Grizzly via ubuntu-users <ubuntu-users at lists.ubuntu.com> wrote:
> 04 May 2021  at 2:49, Bret Busby wrote:

<snip>

>>So, I recommend "something else".
>
> Ok, given 21.04 will be replaced in six months, so wont need to have a huge
> amount of space, what partition sizes do you recommend (I assume I can share
> the swap?) it would be nice to share /Home but I can see that may be a
> problem
> if apps have different versions for 20.04/21.04, so maybe each should be
> self
> contained?
>

I think that this is a bit like the "How long is a piece of string?"
question - the answer depends on the exact nature of the question, as
each user/system will have different requirements.

It is a bit like the proverb that I had previously included in my signature;

"
"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
 Chapter 28 of Book 1 of
 "The Hitchhiker's Guide to the Galaxy:
 A Trilogy In Four Parts",
 written by Douglas Adams,
 published by Pan Books, 1992
"

My personal (and, this applies to only me, as, every person on the
list, will probably have a different answer, depending on the person's
particular system circumstances) application of this, for 21.04, is
that I allowed a 32GB partition for / , did not allocate (used
existing designated partitions) for swap partitions, and, allocated
about 32-64GB for /home (it depended on the applicable circumstances,
for each system).

A number of aspects apply here, for me and my circumstances.

1. At present, I am the only user of my systems, so, before I
installed 21.04 (although, it could equally be done after installing
21.04, and rebooting into each of the older versions, and doing it), I
went into the file manager, and set the permissions on each home
partition, recursively, to grant universal read/write access, so as to
allow files already existent in the existing home partitions, to be
accessed, altered, and, added to. I also use data partitions;
Data0<n>, to take files and data storage, out of the limitations
applicable to /home partitions.

2. This is an important consideration. Each installation; its
applications and its utilities and OS, will have different
configuration and data files, some of which, may be contained in, and,
only in, the /home partition (or home directory, if a separate
partition  for /home is not used), and, a version of a configuration
file, for one version of a package, may not be compatible with an
earlier version of the package; similarly, the structure of, and
component configuration and data files, may vary from one version to
another. A good example of this, is alpine, previously pine, which I
use for my bret at busby.net email. So, a separate /home partition (or,
and, this has severe limitations, and, I believe that the use of it,
is erroneous, although I accept that oyther people may disagree, the
use of a /home directory within the / partition), should be used, for
each version/distribution  installation, to protect the integrity of
configuration and data files, that are peculiar to previous
versions/distributions.

These are the only two aspects, of which I can think, at present, but,
to me, they are important, and, they may be important to only me, but,
I believe that they are worth considering.

I hope that this is helpful.

-- 
Bret Busby
Armadale
West Australia
(UTC+0800)
..............