Confusion - what is a CU or an IU versus a SP???

Hello,  This entry in the Microsoft Project blog is designed to inform those of you who need or want clarification between the Microsoft Office Project Server Infrastructure Update (IU) and the current Cumulative Update from the Office Hotfix process.  So if that is you please read below.

It is recommended for customers to first install the Office Project Server IU before taking on the task of installing the latest CU release.  This only needs to  be done once so if you have installed the IU patch then you can skip the rest of this blog update.  For everybody else still reading, you should follow the instructions as documented for this process here followed by the installation of the CU patch.

This leads most users to ask WHY?  Well let me tell you WHY:

With the IU, when you install Project Server’s update you get MOSS, and the Office Servers full set of changes or at least those which you are licensed to use.  The WSS fix is a separate installation but the IU installation notes direct users to install the WSS changes before installing the Project Server (AKA Office Server) changes.  This ensures that everybody has a complete set of changes and a good version baseline.

With the CU releases customers will only be given the patch if they already have an open service request that is fixed with the CU or if they specifically request the Hotfix patch.  When you receive the the Project Server/Project CU patch no WSS or MOSS changes are included so installation baselines can begin to diverge from a full baseline.  While this is not ideal it also does no harm.  Keep in mind that infrastructure update (IU) is not just bug fixes but also core changes to the product with highly anticipated customer experience improvements. The IU patch can contain changes to Infrastructure code that other applications rely upon.  It is for that reason that we are recommending customers install the IU before the CU.  Therefore, IU does not equal CU and neither of these are full SP releases.  CU is just a grouped set of Hotfixes and the SP is as always a roll-up of Hotfixes with some strategic improvements from the engineering team.  The IU was a hybrid of these so this is a one off release and it comes with a one off installation recommendation.  Normal procedure is to install the latest CU patch and you will get all previous fixes since the last SP where the SP is a broader and will bring deployed systems to a common “baseline” from which Microsoft can continue to provide the highest levels of customer support.

I trust this clears up the difference between a CU, IU and SP patch.