It seems that Windows Server 2008 (previously code-named “Longhorn”) will be the last server OS to come in 32-bit editions (as well as the new 64-bit editions).  In fact, even the R2 (due 2009/2010) may be 64-bit only.

There was some confusion over an announcement that made it sound like Vista will be the last 32-bit OS for the desktop, but this was apparently clarified – they were not saying that.  That doesn’t mean it wont happen of course…

Many desktop computers bought in the last year or two may actually be 64-bit capable, but still have the 32-bit edition of XP or Vista on them, but even 4 years from now, introducing a new OS that wont run on 32-bit machines bought today would likely be a mistake, especially since so many drivers aren’t available for 64-bit.  The average developer -  the early adopting supporter and promoter – can’t be relied upon to promote 64-bit since many developer tools aren’t natively supported.

Anyway, back to servers…

Unless you’re a financial, insurance or communications company rich in cash, a change to 64-bit servers is the kind of change you may consider at the end of a leasing period, so it may take 3 years for adoption to trickle through.

The switch to 64-bit will likely occur an a role-priority basis, probably with mail and database servers first: Exchange Server 2007 already requires a 64-bit edition of Windows Server 2003.  I’m curious to learn if this has stalled take-up of the product.  This also doesn’t help customer-adoption of Microsoft’s Unified Communication strategy I imagine (see my upcoming post on that). 

I can see domain controllers moving up last unless an organisation can make significant WAN-based Active Directory replication gains to be made from the new features in 2008.

Windows Server 2008 also does away with separate builds for single and multi-processor.  Apparently the optimisations for single processor aren’t worth it anymore.

Going 64-bit, breaks the 4GB directly addressable space barrier.  The need to go 64-bit can also be simply related to the population of the planet (which is estimated at over 6 billion, over the 4 billion that 32-bits can represent), pushing the need for larger databases and identifiers.  The same can be said about IPv4 addresses (and they can’t even use the whole range).

If you are thinking about buying new server equipment this year, you may want to think about at least getting 64-bit capable machines.