Linux Mint drops Ubuntu Snap packages

Posted Jul 9, 2020 13:11 UTC (Thu) by mchehab (subscriber, #41156)
In reply to: Linux Mint drops Ubuntu Snap packages by simosx
Parent article: Linux Mint drops Ubuntu Snap packages

> I will go further and say that there is this negative sentiment by some around snap packages, that they tend to blame snap packages for all sort of things that they do not deserve.

Using snap (or similar technologies, like Flatpak) eats a lot of disk space for no good reason (from the user's perspective).

Snap is actually worse than apt (or dnf), as it keeps multiple copies of packages, as they get updated, wasting disk space. In order to avoid that, manual cleanup procedures are required to reclaim disk space:

https://superuser.com/questions/1310825/how-to-remove-old...

Doing that for things that are big, like gnome and texlive actually means a lot of wasted diskspace. This is particularly awful on VM images, where the amount of diskspace is usually very limited.

Linux Mint drops Ubuntu Snap packages

Posted Jul 9, 2020 14:23 UTC (Thu) by simosx (guest, #24338) [Link]

When you are isolating applications, it comes natural that you are using somewhat more disk space.
You can say the same when you use virtualization, or containers.
With snap packages, the snap itself stays compressed.

You can use the "refresh.retain" key to limit the number of older versions of the snap package.
The default is 3, which means that it keeps the last three versions of a snap package. So that you can revert to a previous version without the need to redownload, as long as the older versions are in the same epoch (there are no changes that make a downgrade incompatible).
See more at https://ubuntu.com/blog/how-to-manage-snap-updates

Linux Mint drops Ubuntu Snap packages

Posted Jul 9, 2020 23:42 UTC (Thu) by NYKevin (subscriber, #129325) [Link] (4 responses)

> Using snap (or similar technologies, like Flatpak) eats a lot of disk space for no good reason (from the user's perspective).

Block-level deduplication is not a new technology, and (mostly) solves this problem automatically. Unfortunately, so far as I can tell, ext4 does not support it, and btrfs only does it if userspace manually identifies the affected files and ranges with ioctl_fideduperange(2). Of course, ZFS has proper, automatic support (as far as I've been able to determine from Google), but then you get to tangle with all the fun licensing issues.

The point: This is a (theoretically) solved problem, and the fact that it is apparently so difficult to (practically) solve is actually rather depressing.

Linux Mint drops Ubuntu Snap packages

Posted Jul 10, 2020 4:15 UTC (Fri) by ccchips (subscriber, #3222) [Link] (2 responses)

Snap packages are compressed, so I'm confused about how deduplication will help.

Linux Mint drops Ubuntu Snap packages

Posted Jul 10, 2020 17:13 UTC (Fri) by NYKevin (subscriber, #129325) [Link] (1 responses)

That depends on how the compression works (and whether the Snap people want it to be compatible with block deduplication).

- If you compress each library (or other major component) separately, and then concatenate them, the overall size is (probably) larger, but you can deduplicate effectively.
- If you compress the whole combination, then the overall size is smaller, but block deduplication is probably *less* effective. However, since most compression works by identifying repeated patterns of bytes, it is at least somewhat plausible that you can still do some deduplication anyway.
- If you compress at the block level, after deduplication, then you can have your cake and eat it too. But Snap (probably) doesn't do that.

Again: Theoretically solved doesn't mean practically solved.

Linux Mint drops Ubuntu Snap packages

Posted Jul 10, 2020 21:47 UTC (Fri) by simosx (guest, #24338) [Link]

Ubuntu is moving to using ZFS as the system filesystem.
At the moment you can install Ubuntu on ZFS as an experimental option, on Ubuntu 20.04 LTS.
The immediate benefit is the ability to add restore points.
In LXD, you can run containers and VMs from within the ZFS dataset, without the need to manage partitions.
There is a list of blog posts that explain how ZFS will be used in Ubuntu at https://discourse.ubuntu.com/t/zfs-focus-on-ubuntu-20-04-...
I suppose that there will be some benefits in how snaps are being used.

Linux Mint drops Ubuntu Snap packages

Posted Aug 12, 2020 14:15 UTC (Wed) by mcortese (guest, #52099) [Link]

Block-level deduplication is only applicable to same-version libraries. It doesn't help when a snap package includes v1.0 and another v1.0.0.1