[dm-devel] Weird discrepancy between /dev/mapper/* and /dev/dm-* devices breaks lilo

[Alasdair G Kergon]

On Wed, Jan 31, 2007 at 11:47:37AM +0100, Loïc Minier wrote:
>  When issuing the same dmsetup commands on two device nodes with the
>  same major/minor, the results are puzzling:

The device-mapper ioctls allow mapped devices to be referenced in three ways:
  name
  uuid
  major+minor

The uuid is optional.

dmsetup provides a command line wrapper around the ioctls.  It also
maintains the /dev/mapper directory, creating inodes there called 'name'.
It understands the above three ways of referencing devices: it does not
depend on the existing contents of '/dev'.

Some distributions chose to configure udev to create /dev/dm-N inodes where
N is the minor number.  (I have always discouraged that as a recipe for
confusion: I believe that using configurable names is a better approach.)

Alasdair
-- 
agk at redhat.com