Intel 170 Servers, AS/400 RISC Server, 7xx Servers manual

13.File System Considerations: Web serving performance varies significantly based on which file system is used. Each file system has different overheads and performance characteristics. Note that serving from the ROOT or QOPENSYS directories provide the best system capacity. If Web page development is done from another directory, consider copying the data to a higher-performing file system for production use. The Web serving performance of the non-thread-safe file systems is significantly less than the root directory. Using QDLS or QSYS may decrease capacity by 2-5 times. Also, be sensitive to the number of sub-directories. Additional overhead is introduced with each sub-directory you add due to the authorization checking that is performed. The HTTP Server serves the pages in ASCII, so make sure that the files have the correct format, else the HTTP Server needs to convert the pages which will result in additional overhead.

14.Communications/LAN IOPs: Since there are a dozen or more line flows per transaction (assuming KeepAlive is off), the Web serving environment utilizes the IOP more than other communications environments. Use the Performance Monitor or Collection Services to measure IOP utilization. Attempt to keep the average IOP utilization at 60% or less for best performance. IOP capacity depends on page size, the MTU size, the use of KeepAlive directive, etc. For the best projection of IOP capacity, consider a measurement and observe the IOP utilization.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008	Chapter 6 - Web Server and WebSphere	87