134 CHAPTER 13: P ROBLEM S OLVINGSolving WebcachePerformanceProblemsThe performance of the Webcache is poorCheck: Whether any of the cache storage devices have failed. Examine thefront panel LEDs to ensure there are no faults found. If there are,contact 3Com support personnel. As long as there is at least oneworking cache storage device, the Webcache will operate as a cache,but the failure of a cache storage device will degrade the performanceof the Webcache. If all cache storage devices have failed, theWebcache will pass all requests through to the Web withoutperforming any caching. The Caching Performance graphs in the Device View -> Performancefolder. Specifically check the Hit and Miss Rate graph. If the hit ratepercentage is low, save the system log onto another device in yournetwork. Then use a utility like Webtrends to analyze your web trafficand see if a higher hit rate is expected. Run a network performance test between your client machines andyour Webcache using the Ping command. Check that the responsetime is reasonable. Analyze your network to look for network errors. If you are using Proxy Auto Configuration (PAC) files to configurebrowsers, try setting the browser settings manually to avoid theoverhead of PAC files. If you are using the Web Proxy Auto-Discovery (WPAD) protocol toconfigure the browsers on client machines, try setting the browsersettings manually to avoid the overhead of the WPAD protocol. The Webcache Domain Name Server configuration to check that it canaccess the DNS server.No Web sites can be accessed using the WebcacheCheck the Webcache DNS and Default Router settings, and try to pingthese addresses from the Webcache.Alternatively, if the Webcache is operating in transparent mode, it will notservice Web requests from browsers on client machines that are using theWebcache as a proxy server. None of those client machines will be able toaccess the Web. You must configure the browsers to use another proxyserver and bypass the Webcache, or configure the browsers so that theyare not operating in proxy mode.
