Appendix B - Using Microsoft Windows Server 2003 X64 Editions; Historical Scalability Limitations - HP ProLiant BL685c G5 Performance Manual

Appendix B – Using Microsoft Windows Server 2003 x64
Editions
Microsoft offers a new generation of high-performance platforms for 64-bit applications with
continued support for 32-bit applications and existing deployment and management tools – all on the
same platform. These new operating systems provide an evolutionary path to 64-bit technology,
allowing 64-bit and 32-bit applications to run side-by-side during the gradual migration to 64-bit
computing.
64-bit editions of Windows Server 2003 running on Quad-Core AMD Opteron processors can
improve the performance of HP SBC servers by processing more data per clock cycle, addressing
more memory, and running some numerical calculations faster. Large data sets can be loaded entirely
into memory, reducing the need for slower disk access; complex calculations that take hours to
complete on a 32-bit system can be performed in minutes; and workloads that once required a large
server farm can be performed by a single server.
In addition, this new 64-bit platform also removes many of the limitations that have previously
inhibited scalability in an HP SBC environment.

Historical scalability limitations

32-bit Windows operating systems can directly address 4 GB of memory, 2 GB of which is reserved
for the operating system kernel and 2 GB for applications. Since kernel memory is shared by all
applications, the relatively small size of this space can be particularly problematic in an HP SBC
environment where a server may be responsible for hundreds of users and thousands of processes. In
this scenario, kernel memory can become constrained, making user response times unacceptably long
and effectively limiting the ability of the server to scale up.
Historically, HP SBC environments have been implemented using 1P or 2P servers. Larger, more
powerful servers have typically not been deployed for two main reasons:
• Kernel memory issues have limited the performance of more powerful servers; either a disk I/O
bottleneck occurs or kernel memory is consumed before processor resources can be fully utilized
• Scalability in a 32-bit symmetric multi-processing (SMP) system is inherently non-linear above 2P
With these 1P and 2P server farms, opportunities to scale up are limited. As a result, customers are
forced to scale out, which can create new problems such as deployment and management
complexity, high power and cooling requirements, under-utilized resources, and minimal opportunities
for server consolidation.
The 64-bit platform shatters the earlier 4 GB limitation – for example, Windows Server 2003 R2
Datacenter x64 Edition with Service Pack (SP) 1 supports up to 2 TB of RAM – effectively removing
kernel memory limitations and eliminating disk I/O bottlenecks. By deploying a Windows Server
x64 Edition operating system, customers can fully utilize the resources of their existing HP SBC
servers and take full advantage of new, more powerful systems – whether they are running 32- or
64-bit applications.
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