Mint Installer: if LVM chosen, setup Thin Pool, separate /home and /var LVs

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JeffFromOhio
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Mint Installer: if LVM chosen, setup Thin Pool, separate /home and /var LVs

Postby JeffFromOhio » Mon Sep 25, 2017 5:48 pm

I am a long time Linux user. I recently setup Linux Mint for a non-technical user that I was trying to get their laptop working again, and they didn't have their Windows disk to re-install Windows. I decided while installing that I'd setup the laptop with LVM, so that I could create a good, clean snapshot of the OS after I got it installed and configured for them, so that if the laptop got screwed up, I could revert back to the snap.

I realized after installation that the installer, while it did setup LVM, did not setup a thin pool - this is the newer technology for making snapshots more flexible and space efficient (e.g. if the snapshot actually only needs to take up 4.5G of space, but you created it with 10G of space, you've wasted more than half the space).

Additionally, I noted that it only created a single LV and mount point for / - meaning that if you revert to a snapshot, you lose user data in /home. This is bad practice. If you are going to make it simple to setup LVM (as you do), you should default to putting /home (and probably /var as logs get put under /var, and some apps - particularly stuff like Apache if you want to setup a website, put data files under /var) as their own LVs that get snapshotted and reverted separately.

Additionally, if LVM is chosen during installation, you should consider automatically installing an LVM GUI manager app to make it simple to create and revert snapshots. Also, the GUI snapshot manager could maybe also have backup tools built into it, to let you create a backup (to a USB/eSata hard drive, network drive, tape drive, etc) based on a snapshot or the latest snapshots of all the LVs (e.g. /, /home, and /var).

Maybe the installer media could even let you restore your mint system from a backup created from the snapshots if you have such a backup?

Finally, this might be a bit more difficult even than the previous requests, but, maybe put some infrastructure into place in the boot partition, to allow you to easily revert to a previous snapshot upon reboot (e.g. in the GUI snapshot management tool, select a root snapshot you want to revert to, and click a "Revert To Snapshot" button, and then after confirming you really want to do that, set it up so that when the computer is restarted, it reverts the snapshot with the LVM commands automatically for the user during startup before mounting root to /.

This would make it fantastically easy to use LVM snapshots to manage your system and revert after a problem has occurred.

I realize this is a lot to suggest, but it would also make Linux Mint that much more powerful and useful to ordinary users who might not have the technical chops to:

Reboot the system using the Linux live CD, use the command line to resize/shrink the root logical volume, create new logical volumes, format the logical volumes with a filesystem, mount the new filesystems, move the files from directories on / to the new filesystems (e.g. /home), update /etc/fstab to mount the new home LV as /home, and then use the command line tools to make snapshots of both / and /home logical volumes.

syg00
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Re: Mint Installer: if LVM chosen, setup Thin Pool, separate /home and /var LVs

Postby syg00 » Tue Sep 26, 2017 2:30 am

Given the queries seen here re LVM, I would think it would be a nightmare for the average user Mint is aimed at.
Not to mention the constantly increasing disk space consumed by CoW snapshots that are not regularly cleaned up.

The installer should give a good (simple) base a user can build on as wanted. Constructing what you want - and variations others may want like external (thin) pools - post-install is significantly easier for a knowledgeable user than having every possibility offered as a (more) confusing option on initial install. If the user is incapable of that, then why use it ?.
And is there even a currently maintained LVM GUI ?. system-config-lvm has been deprecated for years.

I'm not in favour at all - no need to be all things to all people.

JeffFromOhio
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Re: Mint Installer: if LVM chosen, setup Thin Pool, separate /home and /var LVs

Postby JeffFromOhio » Tue Sep 26, 2017 9:41 am

syg00 wrote:Given the queries seen here re LVM, I would think it would be a nightmare for the average user Mint is aimed at.
Not to mention the constantly increasing disk space consumed by CoW snapshots that are not regularly cleaned up.

The installer should give a good (simple) base a user can build on as wanted. Constructing what you want - and variations others may want like external (thin) pools - post-install is significantly easier for a knowledgeable user than having every possibility offered as a (more) confusing option on initial install. If the user is incapable of that, then why use it ?.
And is there even a currently maintained LVM GUI ?. system-config-lvm has been deprecated for years.

I'm not in favour at all - no need to be all things to all people.


I'm not at all suggesting to be all things to all people. What I'm saying is that mint *already* allows you to choose LVM during install, but the default LVM setup Mint creates is actually the worst possible LVM setup.

If you're going to provide people one-click setup of LVM, don't make it the worst possible setup.

At a minimum, default to thin-pool LVs (they make far more sense than thick-pool LVs), and default to having a separate root and home LV. That is a much more sane LVM setup for one-click install.

As for the GUI, yeah, there might not be a good GUI to provide people.

mr_raider
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Re: Mint Installer: if LVM chosen, setup Thin Pool, separate /home and /var LVs

Postby mr_raider » Tue Sep 26, 2017 4:18 pm

JeffFromOhio wrote:
syg00 wrote:Given the queries seen here re LVM, I would think it would be a nightmare for the average user Mint is aimed at.
Not to mention the constantly increasing disk space consumed by CoW snapshots that are not regularly cleaned up.

The installer should give a good (simple) base a user can build on as wanted. Constructing what you want - and variations others may want like external (thin) pools - post-install is significantly easier for a knowledgeable user than having every possibility offered as a (more) confusing option on initial install. If the user is incapable of that, then why use it ?.
And is there even a currently maintained LVM GUI ?. system-config-lvm has been deprecated for years.

I'm not in favour at all - no need to be all things to all people.


I'm not at all suggesting to be all things to all people. What I'm saying is that mint *already* allows you to choose LVM during install, but the default LVM setup Mint creates is actually the worst possible LVM setup.

If you're going to provide people one-click setup of LVM, don't make it the worst possible setup.

At a minimum, default to thin-pool LVs (they make far more sense than thick-pool LVs), and default to having a separate root and home LV. That is a much more sane LVM setup for one-click install.

As for the GUI, yeah, there might not be a good GUI to provide people.


The installer is Ubiquity, used by Ubuntu. That's how it is. LVM should have a massive disclaimer on it.
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