Re: [SQU] Tune up Squid Cache Hit

At 06:33 PM 2/20/01 +0800, Awie wrote:
>Folks,
>
>I knew that my topic has recently discussed before. However, I hope you
>will give me comment and suggestion. My Squid seemed running very well as
>transparent proxy now. I also can control it's log growth.
>
>Now, I want to know about CACHE HIT improvement. I set my cache_mem at 128
>MB and 3 GB of cache size.
>
>My questions are:
>
>1. I assume that increasing cache mem and cache size will also improve my
>cache hit. Am I correct?

If you increase your cache size the hit rate can improve if your cache is
currently fully utilized. It depends on the distribution of the accessed
URLs. If your user group browses a small core of sites you will have a good
chance to get a high hit-rate. You can also decide to tune the refresh
rules. This combined with a 12G cache increased my hit rate to 40-55% and
300 users.

>2. What is the default of percentage of "good" cache hit?

That depends on your goal. Mine is mainly increased performance. I like my
50% hit rate. My refresh rules force some files in the cache while the
sites had different intentions. That reduces the dynamic nature of some
sites but that is no problem to me. You also might want to minimize the
network usage. 25% (in bytes) is a good figure to start with in my view.

>3. How can I increase the cache hit? (Please don't tell me to upgrade
>bandwidth)

More cache size, tune the refresh rules (consider caching dynamic URLs from
Ezines and consider ignoring expires headers from cache hostile sites), get
rid of banners (use a redirector based on the add-zapper rule-set for
example). And finally force all users to use the proxy. A router filter on
port 80 does the job (naturally you can't do that when you are an ISP but
for a private network no problem)

Marc

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Marc van Selm
NATO C3 Agency
Communication Systems Division, A-Branch
Tel: +31 70 3142454
E-mail: marc.van.selm@nc3a.nato.int (PGP capable)
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Private: selm@cistron.nl, selm@het.net, http://www.cistron.nl/~selm

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