See also Windows Roaming Profiles

Note the capitalization…

Roaming Profiles synchronizes a user's Windows Profile to the server…on logon and on logoff. So, yes, enabling Roaming Profiles on an AD Domain does cause significant data to be stored on the server. Roaming Profiles allows a user to logon from any workstation and see their same Windows Desktop (Roaming Profile).

Redirected Folders is a newer technique that redirects Windows Profile files/folders to a network share. This has the effect of shrinking Roaming Profiles to a small percentage of the size Roaming Profiles would be without redirection. This makes logging on and logging off DRAMATICALLY faster on networks where Redirected Folders have been implemented.

Roaming Profiles and Redirected Folders on the server are excellent places to back up user data. If you don't back up user profile data here, you would have to back it up on al the individual workstations. NOT.

In the old days (just a few years ago), Roaming Profiles rarely got over 1GB. Even then, users started complaining about slow logon and logoff times. Roaming Profiles are now MUCH larger and REQUIRE the implementation of Redirected Folders to maintain performance during logon/logoff cycles.

Roaming Profiles and Redirected Folders are the BEST features of Windows Servers. Otherwise, I'd put in Linux boxes every time.