--> 04-30.  What's all this fuss about "cleanup backupgroups"?
--> If you used TSM server versions 4.1.x or 4.2.1.x, you most likely
--> encountered a bug in the server code that caused the system objects in
--> your Windows clients' backups to not expire properly. An upgrade to
--> 4.2.3.x or 5.1.5.x fixes the bug, but you have to run
-->         cleanup backupgroups
--> to rid yourself of unwanted versions of the system objects. This subject
--> has been talked to death in the mailing list; go to
--> http://search.adsm.org to review the details.

Beating a dead horse but I think this FAQ answer is incorrect.
AFAIK the expiration bug was introduced in TSM 4.2.2.0 and ITSM v5.1.0.0
(almost sure for the former and not completely for the latter). I think
Gretchen Thiele was the early bird hurt by this bug. There were statements
it affects all platforms except MVS but I cannot confirm this exception.
For sure the bug does not exist in TSM server v4.2.1.15. TSM versions v3.7
& v4.1 (any maintenance/patch level) do not suffer from this bug. The bug
affects both normal operation (growing DB and storage usage) and upgrade
from v4.2 to v5.1 (upgrade errors requiring special handling).

So if I can propose re-wording of the answer:
04-30.  What's all this fuss about "cleanup backupgroups"?
If you had your server upgraded to v4.2.2.0 or v5.1.0.0 and backed up
Windows nodes, expiration of obsolete file versions within "SYSTEM OBJECT"
filespace was not complete. As result TSM database and storage usage were
growing enormously. Upgrade to v5.1 was also problematic.
To resolve the problem new command ("cleanup backupgroups") was introduced
and due to some additional problems the command was further enhanced. This
subject was widely discussed on the list and can be found in archives
(http://search.adsm.org). Read also IBM's "flash" on the topic
(http://www-1.ibm.com/support/docview.wss?rs=663&context=SSGSG7&uid=swg21078582)
and description of APAR IC33977
(http://www-1.ibm.com/support/docview.wss?rs=663&context=SSGSG7&uid=swg186256c3e005f1adc86256c8b00394acf).

Zlatko Krastev
IT Consultant