The Gentoo Base System team has recently switched from the disabling
"device-mapper-only" flag to the enabling "lvm" (bug #718910).
After considering most reverse dependencies of sys-fs/lvm2, the Base System Team has decided that the majority of Gentoo users are unlikely to use the LVM2 components of sys-fs/lvm2, instead relying solely on it providing device-mapper functionality.
To this end, we will disable the default enabled flag "+lvm" on sys-fs/lvm2 on 2023-01-01. If you do not have USE=lvm somehow globally enabled, this means you will lose LVM2 (but not device-mapper!) functionality, so enable it in your config if your boot configuration depends on it or if you depend on any of the lvm2-* daemons.
If you use LVM2 for any partitions, or if you use tools like 'lvchange', you should enable USE=lvm.
Furthermore, we have considered other default enabled USE flags too, and have come to the conclusion that USE=+thin makes even less sense than USE=+lvm. Thin-provisioned LVM volumes are an important use case in certain VM hosting scenarios, but unlikely to be relevant for the large majority of Gentoo users.
In summary:
After considering most reverse dependencies of sys-fs/lvm2, the Base System Team has decided that the majority of Gentoo users are unlikely to use the LVM2 components of sys-fs/lvm2, instead relying solely on it providing device-mapper functionality.
To this end, we will disable the default enabled flag "+lvm" on sys-fs/lvm2 on 2023-01-01. If you do not have USE=lvm somehow globally enabled, this means you will lose LVM2 (but not device-mapper!) functionality, so enable it in your config if your boot configuration depends on it or if you depend on any of the lvm2-* daemons.
If you use LVM2 for any partitions, or if you use tools like 'lvchange', you should enable USE=lvm.
Furthermore, we have considered other default enabled USE flags too, and have come to the conclusion that USE=+thin makes even less sense than USE=+lvm. Thin-provisioned LVM volumes are an important use case in certain VM hosting scenarios, but unlikely to be relevant for the large majority of Gentoo users.
In summary:
- Enable USE="lvm" if you use lvm2 (but not needed for device-mapper) as described above. This includes using LVM for any partitions.
- Enable USE="lvm thin" if you use thin as described above.
- If you don't know what LVM2 is, you don't need to take any action.