Monitoring and Tuning Your Server
About the Inetinfo Working Set
The Inetinfo working set does not have a fixed size. The requirements of the working set vary depending upon the number of connections maintained, the number and size of files, and the use of other supporting services, such as security features and logging.
IIS 5.0 runs in a pageable user-mode process called Inetinfo.exe. When a process is pageable, the system can remove part or all of it from RAM and write it to disk if there isnt enough free memory. If part of the Inetinfo process is paged to disk, the performance of IIS 5.0 suffers. Its extremely important to be sure that your server or servers have enough RAM to keep the entire Inetinfo process in memory at all times. The Web, File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP) services run in the Inetinfo process. Each of the current connections is also given about 10 KB of memory in the Inetinfo working set.
ISAPI DLLs, including ASP, can run in or out of process; in IIS 5.0, ASP processing is done in pooled out-of-process mode by default, and should certainly be run out of process during development and testing. The out-of-process pool is part of the dllhost space, the size of which you can also monitor.
The working set of the Inetinfo process should be large enough to contain the IIS Object Cache, data buffers for IIS 5.0 logging, and the data structures that the Web service uses to track its active connections.