A lightweight slave implementation inside DOT would be a welcome feature.
Just as a brief information point, there is already some *partial* help here in Data ONTAP.
Specifically there are some new(ish) options that will make a filer aggressively cache UNIX group information obtained from an NIS server. The "nis.group_update.enable" controls whether the feature is switched on or not, and the "nis.group_update_schedule" specifies the times of day that refreshes are done. According to my documentation (the "Start Here" guide for Data ONTAP 5.3.5), the former option was new in version 5.3.5, and the latter in 5.3.4, which leads to a rather obvious question that I'll have to let Devi answer! :-)
While this is not exactly what is being requested on this thread, hopefully it demonstrates some good direction.
So why do this just for group information initially? The answer is a little involved, but it had to do with large (gazillion group) UNIX installations that use our CIFS implementation in a UNIX-centric manner.
Keith