Why is 64-bit architecture an advantage in Windows Server 2008?

Answer 1

· Physical memory

A 32-bit system architecture can directly address only a 4-GB address space. A 64-bit system architecture that is running a 64-bit edition of Windows Server can support up to 1,024 GB of both physical and addressable memory.

· Virtual memory

The 64-bit editions of Windows Server can address 16 terabytes of virtual memory by using a flat addressing model. Virtual memory is divided equally between virtual address space for applications and the operating system. Even 32-bit applications can benefit from increased virtual memory address space when they are running in a 64-bit environment. For example, although a 32-bit application is still restricted to 4 GB of virtual memory, it no longer has to share that memory space with the operating system. As a result, it receives an effective increase in available virtual memory.

· Continuous memory

Poor performance in 32-bit systems is often not the result of a lack of available memory, but the unavailability of large enough blocks of continuous memory. In a typical Windows SharePoint Services 3.0 deployment, Windows, internet Information Services (IIS), common language runtime (CLR), ASP.NET, SharePoint Products and Technologies, SSPs, and MDACs can all claim a portion of a server's available virtual memory and can leave a 32-bit address space quite fragmented. When the CLR or SharePoint services request new memory blocks, it can be difficult to find a 64-MB segment in the crowded 32-bit address space. A 64-bit system offers practically unlimited address space for user mode processes.

· Better parallel processingA server that is using 32-bit architecture is limited to 32 CPUs. Improvements in parallel processing and bus architectures enable 64-bit environments to support as many as 64 processors and provide almost linear scalability with each additional processor.· Faster bus architectureA 64-bit architecture provides more and wider general-purpose registers, which contribute to greater overall application speed. When there are more registers, there is less need to write persistent data to memory and then have to read it back just a few instructions later. Function calls are also faster in a 64-bit environment because as many as four arguments at a time can be passed in registers to a function.· More secureThe 64-bit editions of Windows Server offer the following enhanced security features

· Buffer overflow protection

A buffer overflow occurs when a data buffer is congested with more data than it is designed to handle. In 64-bit editions of Windows Server, the first parameters of a procedure call are passed in registers. As a result, it is less likely that the buffer will overflow, because the correct values have to be set up in registers and the variables and addresses have to be aligned on the stack.

· Data execution protection

The 64-bit processors made by AMD and Intel include hardware support for data execution prevention (DEP). Windows Server uses DEP to prevent malicious code from being able to execute, even when a buffer overrun occurs. Even without a processor that supports DEP, Windows Server can detect code that is running in memory locations where it should not be.

· Patch Guard

Microsoft Patch Guard technology prevents non-Microsoft programs from patching the Windows kernel. This technology prevents kernel mode drivers from extending or replacing kernel services, including system service dispatch tables, the interrupt descriptor table (IDT), and the global descriptor table (GDT). Third-party software is also prevented from allocating kernel stacks or patching any part of the kernel.

· Better scalabilityIn a 64-bit environment, not only can database servers gain nearly unlimited virtual memory address space, but they also gain support for more physical memory. It is possible for a 64-bit server that is running 64-bit editions of Windows Server and SQL Server to get very large working data sets entirely into RAM, thereby improving performance and scalability. In addition, the number of application servers that are required to support a given user base can be substantially reduced because a 64-bit environment does not require worker processes to cycle as often. This reduced cycling results in fewer lost connections, improved I/O handling, and a better user experience.· Lower total cost of ownershipAll the benefits of 64-bit operation that are listed in the previous sections enable you to do more with less. A 64-bit environment allows you to manage more data, serve more users, and run more applications while using less hardware. By reducing hardware, you are also able to reduce license, operations, and infrastructure costs. It takes up less floor space in your data center and costs less to maintain. Finally, because a Windows SharePoint Services 3.0 farm that uses 64-bit hardware and software provides more room for growth, you can spend less over time on equipment because the life cycle of your equipment is likely to be longer.