[linux-lvm] logical volume usage type code, equivalent to GPT partition type GUID

Chris Murphy lists at colorremedies.com
Wed Nov 3 17:44:33 UTC 2021


I'm wondering to what degree the current LVM metadata format(s) can
support additional or even arbitrary metadata.

The UEFI spec defines the GPT, and GPT defines a "partition type GUID"
for each partition to define it's usage/purpose, in rather open ended
fashion. I'm wondering about an equivalent for this with LVM, whether
it's useful and how difficult it would be to implement. This is all
very hypothetical right now, so a high level discussion is preferred.

The starting point is the Discoverable Partitions Spec:

Where GPT partition type codes are used to discover file systems, and
their intended use without having to explicitly place them into
/etc/fstab for startup time discovery and mounting. But LVM doesn't
have an equivalent for exposing such a capability, because it implies
many volumes within the larger pool and also the pool might comprise
many devices.

The same problem exists for Btrfs subvolumes, and ZFS datasets.

What might be possible and what is definitely not possible, is what
I'm interested in understanding for now.


Chris Murphy

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