The last write wins – NO, it does not, we do!
Last week I published a blog post around ProfileUnity named: The future looks bright for User Environment and Workspace Management, which, looking at the numbers was very well received – if you’ve missed it you can find it here. Today I’d like to focus on a more specific, and well-known issue that has been with us for many years and does tend to cause some headaches from time to time: the last write wins. Again, this will underline the power and flexibility that ProfileUnity brings to the table.
Last write wins, you say?
If you have been I IT for some time you’ve probably come across the last write wins’ ‘challenge’ once or twice. Before we head over to how ProfileUnity can help, I’ll start with a brief explanation.
During user logon, the user profile is copied down to the local machine the user is logging on to, this will include a file named NTUSER.DAT. The NTUSER.DAT contains the user’s registry settings (HKCU) which are unique for every user. Among other things, it will hold the users’ personal application settings.
According to Microsoft, the NTUSER.DAT is a “central hierarchical database” that contains information about the software, hardware and user profiles contained on a computer.
If we take traditional Roaming Profiles as an example, when a user logs off the NTUSER.DAT file will be copied back to a central file share, from where it was loaded to begin with. If during the session, the user has made any changes to its profile, the existing NTUSER.DAT file will be overwritten (timestamps are compared). Something, which under ‘normal’ circumstances is what we want to happen, otherwise we would lose the changes made. When a so-called mandatory profile is used this doesn’t apply since all users will share the same NTUSER.DAT, renamed to NTUSER.MAN. Nothing is written back to the network share.
However, the problem with the NTUSER.DAT is that it is seen and treated (by the Operating System) a single file, while it holds settings for all our individual user/application settings. Since the NTUSER.DAT (almost) always changes, it will (almost) always be overwritten on logoff, as highlighted above as well. When a user has multiple sessions on multiple machines, the user’s profile will also be loaded at least twice. If changes are made in both sessions, let’s call them session 1 and 2, one will eventually overwrite the other.
Read the entire article here, The last write wins – NO, it does not, we do! | Liquidware Blog
Via the fine folks at Liquidware.