Roaming profiles have also always been restricted to particular versions for particular OS combinations, although some later operating systems have been slightly backward compatible with “v2” profiles. Since the registry is modified in every session, NTUSER.DAT is always written back and will be written back when any “odd man out” session is closed the “last writer wins” (hence the name of the issue), potentially overwriting registry-based settings changes made in other sessions. A user’s hive (mounted to HKEY_CURRENT_USER during a session) is stored in the file NTUSER.DAT in the profile.
This approach works well in the file system, but it fails miserably with the registry, because the registry is a file system within a single file. When Windows writes a locally cached profile back to the file server during logoff, it compares each file pair’s timestamps and overwrites only older files. Traditional roaming profiles have occasionally suffered from issues regarding profile failures and have always been susceptible to “last writer wins” issues when multiple sessions are in use. To avoid problems with large files or large numbers of files, the roaming profile is often combined with Folder Redirection, allowing certain pertinent folders within the profile (usually My Documents, Pictures, and Videos) to be “redirected” permanently onto the network, avoiding the need for copying these particular folders at logon and logoff. This data is then copied back to the user’s %USERPROFILE% area at logon to ensure a consistent user experience across sessions and devices. It rapidly became a crowded space, with other vendors – such as RES, AppSense, Liquidware Labs, Scense and many others – extending, augmenting, or even outright replacing the traditional roaming profile functionality.Ī roaming profile basically allows you to copy the user-based filesystem and HKEY_CURRENT_USER Registry hive to a defined network location at logoff (usually a user’s home drive area or a dedicated profiles share). Microsoft was the first entrant into the market that grew up around user mobility, allowing network-based profiles to persist across multiple desktop sessions.
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