From a recent pmr I had, here's the response  from TSM support:

"I suspect that the
exclude.dir /xx/home
exclude.dir /xx/perflogs
are interpreted as to exclude the /xx/home and /xx/perflogs directories
from the root "/" file system. This is different than to exclude the
file systems themselves. If you want to exclude file systems /xx/home
and /xx/perflogs then use the exclude.fs. For example :
exclude.fs /xx/home
exclude.fs /xx/perflogs
It is better to use the exclude.fs when you want to exclude the whole
file system because the client will not scan the filesystem for matching
directory file specification as it does for an exclude.dir. In other
words, it offers better performance. So, try the exclude.fs and let me
know how it goes. Remember to re-start your client scheduler so that
change takes effect."

--so: My understanding is that if the thing we want to exclude is
a mountpoint for a file system, we should use:
a mountpoint for a file system, we should use:
     exclude.fs /xx/yy        (note no wildcarding)
If it's NOT a mountpoint, then we should use:
     exclude.dir /xx/yy/.../*           (wildcard at will)

This seems to be working for me now, as long as I keep an accurate
inventory of my client's filesystems (and periodically audit this and compare
it to the tsm file spaces!).

fun and games.....JRS
---------------------- Forwarded by John Snyder/CTF on 11/16/2000 10:15 AM
---------------------------
---------------------------
Palmadesso Jack<Jack.Palmadesso AT SWPC.SIEMENS DOT COM>@INTERNET AT VM.MARIST 
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Palmadesso Jack<Jack.Palmadesso AT SWPC.SIEMENS DOT COM>@INTERNET AT VM.MARIST 
DOT EDU> on
11/16/2000 09:01:28 AM
Please respond to ADSM: Dist Stor Manager<ADSM-L AT VM.MARIST DOT EDU>@INTERNET
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Subject:  Re: Anything wrong with this picture?

If you would like to exclude directories then use
exclude.dir

Jack