[This is preliminary documentation and subject to change]
Scaling up means adding resources like RAM or CPUs to a Web server to increase the number of sites that server can publish. Scaling up can be an inexpensive way to scale and boost performance, especially if you host static-content Web sites. For example, an Internet Service Provider (ISP) that wants to scale up can take an existing server that currently houses 5,000 Web pages and by adding more RAM and CPUs may boost that level to 8,000 Web pages. The impact to the budget and resources is limited to adding pieces of hardware, in comparison to adding servers, software licenses, and more administrators to help manage more servers.
One of the primary benefits of scaling up pertains to finding and fixing errors. If performance issues arise, problems are typically easier to locate when scaling up because the number of servers and connections to backend servers has not grown.
Performance results when scaling up are typically not as good as Scaling Out. See About Scalability for a quick summary of the benefits and drawbacks of scaling up versus other methods of scaling. Adding more resources to a server can increase performance, but requests coming into the server have to share resources, which means that performance will not double because you doubled the amount of RAM in a server. Shared resources can result in lock contention, which is a much bigger issue when scaling up than Scaling Out.
Test your server before adding hardware. Use Tools Used to Monitor Performance to establish a baseline for your system's performance and scalability. After installing the new hardware, test the system again to see if the results are positive. If the results are not positive or not as good as you want, see the Scalability Testing and About Network Capacity Planning topics for tips on improving results.
Microsoft.com currently houses information on the Scalable Hosting Solution, an IIS virtual hosting ISAPI filter sample application. The Scalable Hosting Solution (SHS) sample application enhances the ability of IIS to host thousands of static-content sites using an ISAPI filter that provides an alternate approach to configuring individual sites in the metabase. Search for SHS on www.microsoft.com and select the link for Scalable Hosting Solution Overview and Sample Application.
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