Re: access LVM logical volume as disk?

[mlelstv%serpens.de@localhost (Michael van Elst)]

kre%munnari.OZ.AU@localhost (Robert Elz) writes:

>    Date:        Tue, 4 Nov 2025 23:12:05 -0000 (UTC)
>    From:        mlelstv=40serpens.de (Michael van Elst)
>    Message-ID:  <10ee185=24ajm=241=40serpens.de>

>  =7C You can create a ccd device on top of a LV.

>What's the benefit of doing that (assuming just one member of the ccd) ?

>If the object /dev/mapper/vg0-lvpbulk works for gpt, and ccd, then isn't
>that already a device, at least for most practical purposes ?


It is a device, but a simpler thing than a disk, more like a single partition.
It doesn't act like a full disk, doesn't have a disklabel and doesn't handle
the partitioning interfaces nor can you create wedges from it.

A wedge is similar to a device mapper logical volume, you cannot treat
it like a disk either.

The ccd driver is simple enough to handle such a device as a backend
and it then provides the 'disk' properties on top of it.

The vnd driver should probably allow the same, but it rejects devices
as backend. When you remove the check and try, you end in some
recursive locking issues.