[linux-lvm] Identifying useable block devices

Paul B. Henson henson at acm.org
Thu Jan 16 21:03:02 UTC 2014

> Peter Rajnoha
> Sent: Wednesday, January 15, 2014 9:43 PM
> This applies only if the symlinks/nodes are created directly with
> libdevmapper - which is the old classical way.
> If udev is used to manage /dev
> content for dm/lvm devices then the /dev/vg/vol is a symlink to /dev/dm-X
> (also /dev/mapper/vg-vol is a symlink to /dev/dm-X). And dm-X is not a

Hmm, yah, I see on my RHEL6 boxes that is indeed the case, as opposed to my
older RHEL5 boxes.

> As for mount, findmnt and other utilities from util-linux - they all use
> one common code which can handle this situation (e.g. if you call
> "findmnt /dev/vg/vol", it shows you /dev/mapper/vg-vol on output, not
> the dm-X the /dev/vg/vol is referencing actually).

IIRC, this thread started when somebody was being advised *not* to use the
/dev/mapper path, but rather to use the /dev/vg path. If there is special
case handling in util-linux, why isn't it returning what is being advertised
as the preferable path to use rather than the one that is said to be
internal and not to be referenced?

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