I see loads and loads of threads tweets and forum questions which run along the lines of

“What is the upgrade path from [insert any Microsoft Product here] RC to RTM?”

To which the answer is always

“There isn’t one – you have to uninstall RC and install RTM”.

First let me translate the acronyms:

The RC (Release Candidate) is pretty much the final code before RTM (release to manufacture). So RC is the final pre-production beta although in the past there have been RC1 and RC2 around.  Earlier betas are also known as CTPs (Community Technology Previews) and in between these there can be interim builds.

The point of all this is to reinforce the partnership Microsoft has with its customers and partners,

  • Microsoft can crowd test the piece of software in the wild and ensure it is of good quality
  • Customers and partners get an early look at what is upcoming and train and plan accordingly.

However all these betas, CTP’s  including RC are not intended to be used in production, unless you are on an invitation only program like the Technical Adoption Program (TAP).  One of the reasons for this is while the various betas mimic the installation/uninstallation experience of the released product the upgrade option obviously won’t be there as the beat will essentially be upgrading to itself. Occasionally you can get around this by fooling the process as was widely noted for Windows 7 RC to RTM, but you can’t rely on this, so Microsoft’s advice stands; there isn’t an upgrade path from any beta to RTM.

This also applies to service packs which can also have their own betas, whihc brings me to Windows Server 2008 R2 SP1 which has the dynamic memory for Hyper-V in it (BTW there is also the attendant service pack for System Center Virtual Machine Manager (SCVMM) 2008 R2 to support this and is also in RC).  Putting this anywhere near production is especially dangerous as it affects the integration components in the guest virtual machines not just the physical machines running sp1, and so those integration components have to be uninstalled and reinstalled too.  All of this gets even more fun in a cluster as each node has to be taken down and put back again with the possibility that the VM’s will disappear for a while depending on which integration components they have. 

I realise this might be too late to avoid , but if you have done it already then you might want to back out now during the quieter Christmas period (possibly not if you are in the slow clearance business ) rather than wait until the service pack actually ships.