[systemd-devel] Antw: [EXT] the need for a discoverable sub-volumes specification

[Ulrich Windl]

>>> Chris Murphy <lists at colorremedies.com> schrieb am 03.11.2021 um 18:52 in
Nachricht
<CAJCQCtShSvS8sy_sXNc-m7tUXRPOR+RqpBKjTdvJqd4SDiHDeQ at mail.gmail.com>:
> There is a Discoverable Partitions Specification
> http://systemd.io/DISCOVERABLE_PARTITIONS/ 
> 
> The problem with this for Btrfs, ZFS, and LVM is a single volume can
> represent multiple use cases via multiple volumes: subvolumes (btrfs),
> datasets (ZFS), and logical volumes (LVM). I'll just use the term
> sub-volume for all of these, but I'm open to some other generic term.
> 
> None of the above volume managers expose the equivalent of GPT's
> partition type GUID per sub-volume.

At least for LVM I think using a GUID makes little sense as the name of an LV is persistent (until renamed) and unique in a system (sometimes even too unique when using loop mounts).

> 
> One possibility that's available right now is the sub-volume's name.
> All we need is a spec for that naming convention.
> 
> An early prototype of this idea was posted by Lennart:
> https://0pointer.net/blog/revisiting-how-we-put-together-linux-systems.html 
> 
> Lennart previously mentioned elsewhere that this is probably outdated.
> So let's update it and bring it more in line with the purpose and goal
> set out in the discoverable partition spec, which is to obviate the
> need for /etc/fstab.
> 
> 
> -- 
> Chris Murphy