directory instead of link for thinpools?

[Oliver Rath <rath@mglug.de>]

Hi list,

Im using thinpool-devices for a longer time (3+ years) and thinking
about a more intuitive representation in /dev/.

If Im right, Thinpools are not used directly (as device), only as pool
for thinpool-based devices (these with --virtualsize instead of --size).

I.e. we are using "vg" as volumegroup and "pool" as thinpool,
"pooldevice" a "pool" based virtual device and "standarddevice" a normal
(non-thinpool) lvm-device, then following happens:

- /dev/vg/pool is a link to /dev/dm-X, which is a device node, but never
  used directly
- /dev/vg/pooldevice is also a link to /dev/dm-Y, but now it is useable
  directly
- /dev/vg/standarddevice is also a link to /dev/dm-Z, useable directly,
  but not snappable like thinpool devices

This is imho a bit confusing.

My idea now would be to change the representation of "pool" from a link
to this (never directly used) device to a directory, which includes the
links to the pooldevices. Now the representation would look like this
("/" is dir, "@" is link):

/dev/vg/standarddevice@
/dev/vg/pool/
/dev/vg/pool/pooldevice@


Now I tried to create this with udev-rules, but unfortunatly I didnt
find any possibility to differ between standarddevices, pools and
pool-based devices. Is there any possibility to recogize this for
udev-rules?

What do you think generally about this idea?

Tfh!

Oliver