Windows Server 2003, with its hundreds of small improvements and refinements, is an evolutionary upgrade from Windows 2000 Server. But two areas where Windows 2003 proves to be a dramatic improvement over its predecessor are performance and scalability. Indeed, the numbers are impressive: On identical hardware, Windows 2003 performs twice as fast on average as Win2K Server. Here's what you need to know about Windows 2003 performance and scalability.

A Faster File Server
Windows 2003's better caching algorithms and memory management improvements make it a dramatically faster file server than Win2K Server, with 85 to 140 times the I/O bandwidth on the NetBench throughput benchmark and as much as 75 percent higher NFS Server performance on SPEC SFS v3. And Microsoft claims that ChkDisk is as much as 600 percent faster than earlier versions.

For Active Directory (AD), significant scaling improvements in Windows 2003 make all aspects of directory performance, including searching, site replication, and overall performance, much greater than with Win2K Server. In the initial AD version, Win2K's scalability limitations actually caused some 8-way systems to underperform 4-way systems. Now, customers will see about 500 percent better performance on an 8-way system when compared to a 1-way system, and about 70 percent better performance when compared to a 4-way system.

Microsoft says that Windows 2003's memory management improvements will deliver up to 140 percent higher user capacity in Win2K Server Terminal Services. General networking improvements—a faster TCP/IP stack, VPN system, and improved drivers and scalability—will lead to dramatically faster out-of-the-box performance. TCP/IP performance is about 25 percent faster, while the VPN outpaces the Win2K version by about 20 percent. DNS queries are 120 percent faster, and FTP access features 125 percent higher throughput.

A Faster Web Server
Windows 2003 also significantly improves Microsoft Internet Information Services (IIS) 6.0, which has a completely rewritten process model and a kernel mode Web driver. IIS 6.0 also features better caching heuristics to help handle cache hits and misses more intelligently than previous versions. On various WebBench benchmarks, IIS 6.0 outperforms IIS 5.0 by 30 to 170 percent, depending on the scenario. For Web hosting, IIS 6.0 takes advantage of Windows 2003's scalability features to host more sites per box—as many as 50,000 static sites on a machine with 2GB of RAM—and improve throughput to those sites as much as 245 times at the 10,000-site limit that IIS 5.0 imposes. And startup time is dramatically faster—as much as 14 times faster than IIS 5.0, depending on the number of sites.

A Faster Database Server
Because of its architectural improvements, Windows 2003 now scales to 32-processor systems with 64GB of RAM on the 32-bit Intel x86 architecture and 64-processor systems with 512GB of RAM on the 64-bit Itanium family. Database servers running on Windows 2003 can also take advantage of improved Hyper-Threading Technology on newer Intel chipsets, improved Non-Uniform Memory Access (NUMA) capabilities and improvements to the I/O path, key system locks for scheduling and memory management, and kernel structures that are optimized for new hardware. Before Windows 2003, the highest performing database on Windows was a 32-way Pentium III Xeon 900MHz Unisys ES7000 system, which scored 164,218 transactions per minute (tpmC) on the industry standard TPC-C non-clustered benchmark. With Windows 2003, a 32-way NEC Express5800 system with 1GHz Itanium chips achieved 342,746 tpmC, placing Windows in the top 10 for the first time for this benchmark.

Recommendations
The performance and scalability improvements in Window 2003 practically scream "server consolidation," with many of the product's enhancements coming from major scheduling, memory management, and I/O improvements. If you're running into performance or scalability ceilings in Win2K Server or you want to consolidate servers to save money, Windows 2003 is a no-brainer.