[lvm-devel] directory instead of link for thinpools?
Oliver Rath
rath at mglug.de
Thu Mar 3 10:17:30 UTC 2016
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
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