Viewing Why Requests Are Not Sent From The Cache - Nortel BayStack Instant Internet 100-S Using Manual

216 Chapter 7 Web cache configuration
When you evaluate the cache statistics, consider the following:
• Hit Rate Statistics – The hit rate displays the number of times the Instant
Internet unit returned information from the cache rather than a Web server.
Expect a hit rate of between 25% to 45%. A high percentage indicates that
information is being sent from the cache and the Instant Internet unit is
operating efficiently.
If the hit rate is lower, do any of the following:
— Move up one cache level, for example, from Moderate to Aggressive and
— Review the statistics for "Why requests are not served from the cache"
• Single Hit Statistics – If the statistics for a single hit is high (the 1 request
statistic in the Cache entry request count area), the Web entries are being
requested only once which decreases the cache statistics. Web caching is most
effective when multiple users request the same Web content.
Typically, when the statistics for entries with a single hit are 70% or less, the
cache statistics are higher (40% to 50% hit ratio). If the statistics for single hit
entries are above 80%, the cache statistics are lower (20% to 30% hit ratio).
These statistics can vary depending on cache usage.

Viewing why requests are not sent from the cache

When a user requests Web content, the request passes through the cache and is
evaluated. The requested entries are sent from the cache whenever possible.
When a request is not fulfilled from the cache, it is typically because the entry has
expired. In this case, the request is fulfilled from the originating Web server.
In addition to expiring, there are other reasons that entries are not sent from the
cache. The Instant Internet unit tracks and records statistics about these entries
that are not sent from the cache. You can improve some of these statistics by
tuning the Instant Internet unit to enable certain types of special Web requests to
be sent from the cache.
To increase the number of entries sent from the cache, review the following
statistics for why requests are not sent from the cache and then fine-tune the cache
settings accordingly.
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see if the change increases the hit rate.
and adjust the settings to increase the number of hits.