224 CHAPTER 14: P ERFORMANCE M ONITORINGThe Webcache has its own internal cache of DNS entries. The DNS HitRate shows how effective this cache is being in avoiding DNS lookups tothe DNS server.Viewing SystemPerformance GraphsTo view the System Performance graphs select System from thenavigation tree. The following items will be displayed: CPU LoadThe average and maximum percentage of load on the Webcache’scentral processing unit (CPU). Memory UsageThe average amount of physical memory in megabytes that is beingused in the Webcache. Buffers and Cached Memory UsageThe amount of memory in megabytes used by the Webcache’soperating system as buffer memory and cache memory. Swap UsageThe amount of disk space in megabytes used by the Webcache’soperating system as swap space. Cache Storage UsageThe percentage of the caching disk(s) currently in use. Space is clearedon the caching disk(s) only when it is needed. The Webcache does notcontain any cached articles when it is first deployed so the CacheStorage Graph starts at 0% and increases towards 100% as articlesare cached. If the cache is cleared, the Cache Storage Graph willreturn to 0%.EmailingPerformanceGraphsYou can set up automatic emailing of the performance graphs tospecified email accounts, enabling you to easily demonstrate the benefitsof the Webcache to other people within your organization. You canspecify how often the performance graphs are emailed and who theemails are sent to. Each graph is attached to the email in PNG file format.The email also contains text that indicates which Webcache sent theemail, the date on which the email was sent and the period of time thatthe graphs cover.dua1611-5aaa04.book Page 224 Friday, November 29, 2002 8:56 PM
