Occasionally, TSO (CMT Technical Services Organization) gets the following question from customers and salesmen alike, even after consulting Symantec’s Enterprise Vault Compatibility Guide:

Does Enterprise Vault 8.0 is supported on 64-bit Windows servers?

The short answer to this question is:

YES, but it runs as a 32-bit application on the 64-bit OS.

For those that would like to understand more about what this means, the following is for you.

Foundations
When companies create software, one of the decisions they make before any code is written is: what is the target Operating System and hardware for their application. Companies answer this question a multitude of ways. Often, the decision is influenced by cost, but also the perceived business opportunity, available talent, and a series of technical engineering decisions that relate to the capabilities of the software they are designing. The decision to write for a 32-bit or 64-bit architecture is one of the technical decisions. The choice affects the frameworks the program is written against, the amount of memory they expect the application to use, how much IO activity they need for top performance and much more. As a general rule, however, companies choose 64-bit applications for the expanded availability of memory (RAM) to their application.

Why is that? Well, it’s a numbers game. 32-bit applications run with a 32-bit instruction size and can address up to 32-bits worth of memory. 32-bits is the same as multiplying 2, 32 times (2x2x2….), which equals 4,294,967,296 bits. Each bit can address one byte of memory, which makes the total amount of memory available for a program to be 4GBs. That’s a lot of memory, right? Actually, no. If you include the space that the OS takes up in memory, plus overhead, that 4GBs of memory is greatly reduced. In fact, in a default Windows 2003 system the most memory that a single process can consume (without OS modifications) is 2GBs. When you are running high performance applications like Microsoft Exchange or a SQL Server database, that is not much memory with which to work.

By comparison, a 64-bit application can theoretically address a maximum of 18,466,744,073,709,551,616 bytes or over 16 million TBs (or 16 Exabytes)! That is a lot of memory. As a point of reference, the estimated size of the entire internet is at 500 exabytes. As can be expected, no manufacturer actually attains this capacity. Each company has their own limits. Intel’s latest 64-bit processors can address up to 64GBs of memory.

The Path to 64-bit
With all of that additional memory capacity why are not more applications being written as 64-bit applications? Increasingly, they are. But it is important to note that 64-bit hardware and software is still only a few years old for mainstream Operating Systems and Intel/AMD x86 server hardware. As such, developers are still in the long process of transitioning their code. In fact, many applications are unlikely to receive any benefit from moving to 64-bits and, as such, may never get converted. They just will not perform any better on a 64-bit processor and it would be too costly to rewrite them.

When AMD introduced 64-bit capabilities to x86 processors, they designed a solution that allows developers to transition to 64-bit at their leisure. This was quite different than the approaches that other processor manufacturers took. Ultimately, it was the most successful and beat out Intel’s design.

The processor AMD created included both the full 32-bit x86 instruction set (which was used by all mainstream AMD/Intel processors up to that point) and a full set of brand new 64-bit instructions. Once the processor had both 32-bit and 64-bit instruction sets, the same chip could run both 32-bit and 64-bit applications.

Up to the Operating Systems
Once the processors had this capability, it was up to Operating System vendors like Microsoft to support the new 64-bit instructions. Microsoft began including support for 64-bit processing with dedicated 64-bit versions of Windows Server 2003 and Windows XP. This support was further extended with the release of 64-bit versions of Windows Server 2008 and Windows Vista. In each case, Microsoft provides the ability to run 32-bit applications on a 64-bit OS through a 32-bit emulation layer called “Windows-on-Windows 64-bit” (or WoW64).

The WOW64 emulation layer allows 32-bit applications to access Operating System functionality via 32-bit instructions that are then translated into the proper 64-bit instructions. Also, WoW64 controls the switching of the processor between 32-bit and 64-bit modes. In order to maximize backward compatibility, WoW64 is automatically launched when a 32-bit application is run. As such, users who run applications on 64-bit versions of Windows often are unaware of which applications are running in 32-bit versus 64-bit modes.

Enterprise Vault and WoW64
We have come now full circle to the question at hand: does Enterprise Vault 8.0 run on a 64-bit Operating System? If you consult the Enterprise Vault 8.0 Compatibility Guide, it will show that EV 8.0’s Windows 2003 64-bit support is as follows:

• Windows Server 2003 x64 edition (using WOW64) OR, SP1 – not supported
• Windows Server 2003 x64 edition OR, SP1, SP2 – not supported
• Windows Server 2003 x64 edition (using WOW64) SP2 – supported as long as the SMTP module is not used

Without a knowledge about what WoW64 is, it could be pretty confusing about whether or not EV 8.0 is supported on Windows Server 2003! In fact, it could be easy to conclude that it is not supported. What the Compatibility Guide is attempting to communicate here is that Enterprise Vault 8.0 will not run as a native 64-bit application, but it will run as a 32-bit application on Windows Server 2003 x64 SP2 through the WoW64 emulation layer.

For Windows Server 2008, the Compatibility Guide states 64-bit support as follows:

• Windows Server 2008 x64 edition (using WoW64) OR – supported as long as the SMTP module is not used and Microsoft hotfix #949516 is applied to the OS.
• Windows Server 2008 x64 edition OR – not supported

Again, the Compatibility Guide here is simply stating that Enterprise Vault 8.0 is not a 64-bit application, but will run on Windows Server 2008 x64 through the WoW64 emulation layer as long as a hotfix is applied to the OS.

Performance Impact
Anytime someone reads or hears that their application will run through an emulation layer, they think: performance degradation. So would Enterprise Vault run better/faster on a 64-bit Operating System in theory, but due to emulation actually run slower? According Symantec’s own Enterprise Vault 8.0 performance guide, EV 8.0 has exactly the same performance regardless of it running on 32-bit or 64-bit WoW64 emulation.

The Future
Will Symantec Enterprise Vault ever be a 64-bit application? That is a good question. Today, I do not know. But what I do know is that once EV goes 64-bit, it will because the Symantec Enterprise Vault team conducted a thorough analysis of the business and engineering benefits, and challenges, with moving to that platform and decided that it is in your best interest to upgrade to a 64-bit version of Enterprise Vault. For all I know they could be working on it today to enable even more great features. Or to provide even better performance. Until then, however, know that you are running the best archiving and eDiscovery platform available on the market regardless of how many bits it is.