ISA 2004 cache usage breakdown (Full Version)

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Optic -> ISA 2004 cache usage breakdown (6.Sep.2005 3:00:00 AM)


Recently for the first time I decided to have a look at the Reports that ISA 2004 can produce. I generated a report for the entire month of August 2005 with all the options.

Part of the report is the "Cache usage breakdown". I was initially impressed to find that roughly 50% of our HTTP traffic is returned from the cache (some with and some without verification). Not bad, I thought.

I then noticed the actual figures next to the percentages and found them confusing. It is showing only 2.5Gb total traffic. So I am saving about 50% of this.

However, we do approximately 30Gb of traffic per month and the vast majority of it is HTTP. In another section of the report I can look at the "Top Websites" (which includes a line for "All Others") which shows a total amount of traffic at around 30Gb.

I tried generating reports for different months and found the same thing each time. The total HTTP traffic was around 30Gb, with the total "Cache usage breakdown" between 2Gb and 3Gb.

Can someone explain why this is so? I would have expected the "Cache usage breakdown" to show roughly 30Gb as the total as well, and then a certain percentage of this would be returned from the cache. Why is it that only 2-3Gb seems to even go through the caching process?

If the numbers ISA is reporting to me are correct then it is hardly worth running a cache at all. To save 50% of 2Gb is hardly worth the expense of a set of quick U320 SCSI drives in a RAID 10!

Am I missing something?


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