[clug] Upgrade to Ubuntu 16.04 problems

[Chris Smart]

On Wed, May 04, 2016 at 04:41:14PM +1000, Hal Ashburner wrote:
>Hi-jacking the thread..
>
>On 4 May 2016 at 15:17, Chris Smart <clug at christophersmart.com> wrote:
>
>> OK, I don't know what the defaults are, but any sane distro will
>> normally put your /home on a separate partition by default.
>
>I was wondering why this is best practise. Especially on a laptop
>where now you have to estimate how much disk you need for your system
>so will likely leave extra and have a hole in that you can't fill with
>useful data like your music, photos, movies etc. It must effectively
>reduce the size of  your usable disk.
>

I think it's flexibility.

To me the most important feature is the ease of re-installing or
dual-booting multiple distros and sharing the same home dir. Just format
all your other partitions and but just mount /home and you're done. You
don't need to move data off, or mount the partition to delete all the dirs
except /home and then mount without formatting, etc. In the case of dual
booting, you have separate partitions for / and share the same /home
with the same user id.

There are other benefits too, like filling up your home directory won't
render your system unbootable. You can set extra mount options like
noexec to prevent execution of binaries, or different atime or journal
and commit settings. You can even use a different file system, perhaps
one that lets you do snapshots. You could also setup /home specific
encryption, separate from the rest of the system.

You could put /home on an SSD rather than on spinning rust, or it could
be on a RAID array that protects your data while the rest of the system
is on a faster, non-protecting RAID level as you don't care as much.

The issue of not knowing how much space you need is often addressed by
using LVM, which is the default for a number of distributions. You can
start small and grow as needed. You can create a new partition for
something else in the free space, like vm images under /var/lib/libvirt
or something. You could add another disk and just grow /home to get more
free space.

These days, btrfs is probably the way to go, where /home can be a
subvolume and therefore separate while sharing the space with /.

Of course, none of that is a substitute for decent backups.

>
>You can still rsync just your /home off if everything is on one partition.
>I'm worried I am missing something important. (I've never had a disk
>that was big enough...)
>

Yeah you can always rsync something off but that's inconvenient and
takes time. If you have to quickly reinstall to fix something, that's
not going to work well and you'd do something else like mount and delete
everything except /home dir, then return the installer and mount to /
without formatting.

But a separate /home is just so much easier.

-c