Domino 32 bit vs 64 bit – how to decide

I my last post I talked about what the main advantage of going 64 bit Windows for Domino – shared addressable memory – but I really did not go into detail on whether 32 bit or 64 bit Domino is the better choice for an installation.

As I mentioned previously, the main advantage of going 64 bit Windows is that your Domino instance will not have 4 GB of addressable shared memory available. The kicker is that this holds true for both 32 bit and 64 bit Domino on 64 bit Windows. This fact came as quite a surprise to me when I found out, this is due to the way that the Domino memory system and the memory handles are currently designed.

So the question becomes, why would I choose 64 bit Domino if 32 bit does the same for me?

Personally, I believe the main deciding factor is whether you plan to run add-in tasks in your Domino instance or not. To run an add-in task on a 64 bit Domino server the add in task also needs to be 64 bit. To run an add-in task on a 32 bit Domino server the add-in task needs to be 32 bit as well.

The logical conclusion therefore is: if you plan to run ANY add-ins (e.g.: Anti Virus, etc.) on your 64 bit Domino server you need to determine if that program is available in 64 bit as well. If it is and any other products you might consider running are available in 64 bit as well – then you can go ahead (but test first anyway – of course!!) and install 64 bit Domino. If this is not the case your choice will need to be 32 bit Domino.

“Elementary, my dear Watson.”