I guess that I will try one more time... /proc is an illusion. It does not actually consume disk space.

If you create a new process with, say pid 1234 and it is using 300 MB of memory, /proc/1234 will magicly pop into existence and it will be 300 MB in size. But you did not lose any disk space. Not one byte.

Now, kill pid 1234 and /proc/1234 will vanish. But you won't get back even one byte of disk space. /proc/1234 is just a way to treat a process as if it was a data file. This makes stuff like debuggers very easy to write.

/dev, on the other hand, is probably a real problem. It is usually caused by someone doing something like:
tar cvf /dev/wrong-name-for-tape-drive /big/collection/of/files

Maybe:
find /dev -type f
will find it for you.

Hola,
i have found the culprit leading to high root usage. /dev/rmt/0n has taken huge amount of disk space.

Things have went back to normal now! Thanks for your 'clue'. =)