Just to clarify, if you are using UNIX style authentication for CIFS clients then there is a limit of 32 groups per username.
I've seen this information in a NetApp knowledge base article, sorry I don't have the reference handy.
If you are using NFS to access the filer then the limit is determined by the client OS. The limit is 32 for most UNIX versions (e.g. Linux), but 16 for some such as MacOS X. This limit includes the primary group.
Additionally, NIS imposes a limit of 1024 characters in a record (line). This is a limitation of NIS, not the UNIX group system per se. The work-around is to have multiple groups with the same GID but slightly different names.
HTH, Jeremy
-- Jeremy Webber Senior Systems Engineer Animal Logic Pty Ltd Phone: +61 2 9383 4837 Fax: +61 2 9383 4801 Switch: +61 2 9383 4800