Add advanced partitioning options to server installer

[Douglas Thor]

## General Info

Type: Feature Request
Item: Server Installer

## Description

The new installer introduced in 18.04 (not sure what the installer is called, sorry) is great, but there are some settings that are no longer accessible specifically with respect to partitioning. I completely understand wanting to simplify the interface for common options, but the advanced stuff should still be available.

With the modified Debian installer used in 16.04, users could edit the following partitioning options and more:

+ Primary vs logical partitions
+ Whether to use LVM or not
+ Inode size
+ mount options like `relatime`
+ reserved block percentage

The new installer in 18.04 and later does not allow admins to set some of the above. To me, at least, the important ones are **inode size** and **mount options**. I would like to see these advanced options implemented.

## Current Workarounds

1. Use the alternative Ubuntu Server Installer http://cdimage.ubuntu.com/releases/18.04.3/release/ubuntu-18.04.3-server-amd64.iso, but I don't know how long that will be maintained or available.

2. Modify mount/partition settings after server installation.

[Ryan Harper (raharper)]

Thanks for filing the bug.

For subiquity devs:

curtin's mount handler supports additional mount options:

https://curtin.readthedocs.io/en/latest/topics/storage.html#mount-command

However, curtin does not accept additional flags/params to the mkfs command that's used. This is what would be needed to support optional features for things like inode size, reserved block;

[Michael Hudson-Doyle (mwhudson)]

> + Primary vs logical partitions

Subiquity so far only creates GPT partition tables. I guess one day we will probably add support for editing DOS partition tables but I would like to keep the assumption that any partition tables we create are GPT. It's 2019 after all.

> + Whether to use LVM or not

LVM has been supported for a while now.

> + Inode size
> + mount options like `relatime`
> + reserved block percentage

These are all fair. Inode size is the only one that can't be changed after the fact though, so it's probably the most important.

[Wolfgang Schwarz (oyano)]

Hello,
whereas in the Lubuntu 18.04 installer one can choose to create a LVM filesystem this option is no longer available in the Lubuntu 20.04 installer.
Having good experiences with LVM under Lubuntu 18.04 I would like to run Lubuntu 20.04 also with LVM. However I did not yet succeed in converting a normal filesystem into LVM without loosing the whole Lubuntu 20.04 installation in spite of some hours spending in trying out some of the published tricks.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.