AMD released their Opteron 64-bit CPUs last year, and Microsoft is getting ready to release a 64-bit version of Windows Server 2003 that will run on them. A lot of people are wondering how these upcoming 64-bit environments will affect Citrix and Terminal Services.
Simply moving to a 64-bit platform will not necessarily increase performance over today’s 32-bit systems. However, there’s one key reason that I’m particularly excited about 64-bit Windows: The 32-bit Windows 2GB kernel memory limit. Terminal Server or Citrix systems running on 64-bit operating systems will not hit the same kernel memory limits that 32-bit versions run into today.
Let’s take a look at the 64-bit offerings that are (or soon will be) available.
First, we should mention that a 64-bit version of Windows Server 2003 has been available in a final and stable form for a year now. However, today’s 64-bit Windows only works on Intel’s Intanium2 CPUs. Unfortunately, the use of Itanium never caught on in Windows environments. Even today’s Itanium clock speeds top out at only 1.5GHz and their costs are astronomical. (A 1.4GHz Itanium2 CPU is $1400.)
People have pointed to Itanium and said that 64-bit Windows computing is far, far away, but the truth is that the Itanium was just a bad design that cost too much. Even Intel has essentially admitted this, and they’re dumping the entire Itanium line and copying AMD’s 64-bit CPU architecture.
Understanding the 64-bit AMD Opteron Processor
While Intel and HP were throwing marketing money at the Itanium, AMD was quietly developing its own 64-bit processor architecture from scratch. Codenamed “Hammer,” this architecture is the foundation for both the AMD Opteron and AMD Athlon64 processors. (Opteron and Althon64 are more-or-less the same thing, with Opteron being the server version and Althon64 being the desktop version.)
The most unique aspect of this architecture is that it allows CPUs to act as hybrid/convertible between 32- and 64-bit environments. These CPUs have three modes of operation:
- Legacy 32-bit mode
- 64-bit mode running 32-bit applications
- Full 64-bit mode, running a 64-bit OS with 64-bit applications
In the legacy 32-bit mode, you can use an Opteron system just like any other x86 32-bit system from Intel. You can install Windows 2000 or DOS or Windows 98 or the regular 32-bit Windows Server 2003 or pretty much whatever you want on an Opteron system. The system will behave like any standard Intel x86 32-bit system.
In fact, when comparing Intel Pentium 4 Xeon systems with AMD Opteron systems running 32-bit operating systems, the Opteron systems tend to offer better performance. This has absolutely nothing to do with the fact that it’s a 64-bit chip (since it’s running in 32-bit mode anyway.) Instead, AMD increased 32-bit performance by integrating the memory controller onto the chip itself and adding some new CPU registers.
When you’re ready to move up to a 64-bit operating system, you can do so with the same Opteron system you previously had a 32-bit OS running on. At this time, the 64-bit version Microsoft Windows Server 2003 for AMD chips is in beta, and it will be released when Microsoft releases Service Pack 1 for Windows Server 2003. (The new 64-bit version of Windows 2003 for AMD Opteron will have SP1 built in.)
64-bit Opteron systems cost about the same as 32-bit Intel P4 Xeon systems, and you can buy them from IBM and HP. I personally built a complete Opteron system for testing for under $1000.
From a software standpoint, there is no price difference between the 32- and 64-bit versions of Windows Server 2003, although the bigger hardware available means that most people who use 64-bit Windows Server will be require the Enterprise or Datacenter editions of Windows.
Once you have your 64-bit Opteron system up and running you’ll be able to install 32- or 64-bit applications.
64-bit Terminal Services
The 64-bit version of Windows Server 2003 looks and feels exactly like the 32-bit version. Terminal Server works fine in 64-bit. In fact, users can even move back and forth between 32- and 64-bit Terminal Servers without any problems. Logon scripts, GPOs, profiles, and printing all work the same in 32- and 64-bit Windows.
Since there aren’t really any 64-bit desktop applications available today, 64-bit Terminal Servers are going to end up running 32-bit applications.
This leads to an interesting design decision. With an AMD Opteron system, will you get better performance by installing 32-bit Windows with 32-bit applications or 64-bit Windows with 32-bit applications? (After all, this is the first time that we actually have a choice as to which version of the OS we can install on a specific system.) AMD claims that the 64-bit OS will yield better performance even with 32-bit applications, although I haven’t yet personally tested this head-to-head.
64-bit Citrix MetaFrame?
The only downside to running a 64-bit version of Windows is that some 32-bit applications (especially system-level applications) will simply not work. Citrix MetaFrame is one of those applications. Today’s version of Citrix MetaFrame Presentation Server simply will not install on a Terminal Server running the 64-bit version of Microsoft Windows Server 2003.
I would imagine that it would also be “hit or miss” with the third-party server-based computing applications, such as performance management and printing solutions.
So when will Citrix release a 64-bit version of MetaFrame Presentation Server? No one knows. When asked, Citrix officials have said that they build all their products based on market demand. When people start using 64-bit Terminal Servers in force, I’m sure we’ll see a 64-bit version of MetaFrame.
The Chicken or the Egg
Microsoft is certainly doing their part to push people towards 64-bit computing in the Longhorn timeframe, and we’ll certainly see a 64-bit version of MetaFrame Presentation Server at some point. For now, it looks like 64-bit Terminal Servers will shine in “Terminal Server only” environments (where it will be a no-brainer for larger implementations).
I still have my Opteron server, and I’ll continue to do more testing over the next few months.