User manual

Chapter 3
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• Cache hit rate. This number refers to the ratio of cache hits to
total cache requests.
• Average cache hit object size. This is the average (mean)
document size for documents which were delivered from the
cache.
• Average cache miss object size. This is the average (mean)
document size for documents which had to be retrieved from
their original servers.
• Bandwidth savings. This number reflects the amount of
client HTTP traffic that did not result in documents being
downloaded from the Internet, which results in saved
bandwidth.
• Average cache hit latency. This is the average (mean)
amount of time (in seconds) it took the CacheRaQ to deliver a
document from its cache to a client. The time measured is the
difference in time between the time that the CacheRaQ
receives the request initially to the time that the CacheRaQ
has finished sending the complete object to the client.
• Average cache miss latency. This is the average amount of
time it took the CacheRaQ to deliver a document that had to
be requested from the original server. It is calculated
similarly to the cache hit latency (above), with the exception
that only cache misses are considered.
• Weighted average request latency. This is the average cache
hit latency multipled by the cache hit rate, plus the average
cache miss latency multiplied by the cache miss rate (cache
miss rate is one minus the cache hit rate).
• Request speedup. This number quantifies the CacheRaQ's
performance improvement in terms of user-perceived
latency. It is the ratio of cache miss latency to weighted
average request latency.
The Summary Statistics output also includes three graphs. These
graphs illustrate the number of requests as a function of time of
day, the number of cache hits vs. cache misses as a function of
time of day, and the average cache hit latency vs. average cache
miss latency as a function of time of day.
Usage Statistics. Four options let you view HTTP traffic statistics
for individual clients (users) and individual HTTP servers. Each
option returns a list of client or server hostnames, and for each
hostname, a count of documents sent/received and a count of
bytes sent/received: