Re: [squid-users] How many proxies to run?

Ho Rex

On Tue, Aug 30, 2011 at 2:46 PM, rex_ray . <rex_ray_at_sify.com> wrote:
> Hi,
>       We are a Public University offering free internet access (both
> wired/wireless) to students through three Squid Proxy Servers.The
> number of peak time users even reach more than 3000. To my knowledge
> these proxies are running without any optimization. Also Proxy users
> are always complaining about the slow speed of the net. I inherited
> this setup from my predecessor a week ago,though am a linux
> administrator am new to the world of Squid Web Proxy. I have the
> following questions regarding Squid.
>
>   Is it really necessary to run three proxy servers to support more
> than 3500 users?

Unfortunately the number of users is not a relevant unit to measure
load to a proxy, as the actual load depends a lot on the users'
behavior.
In addition to the OS it runs on, squid offers a wide number of
diagnostic tools to help understand how it is behaving. Among them,
the Cache Manager (http://wiki.squid-cache.org/Features/CacheManager),
a built-in SNMP agent (http://wiki.squid-cache.org/Features/Snmp), a
customizable log (http://wiki.squid-cache.org/Features/LogFormat)
which includes in its default format the time taken for each
transaction to be analyzed by third-party or custom statistics
software.

>  Am asking this question because now users have to configure either
> one of the three proxy addresses in their browsers(a real hassle) if
> they want to browse. I was hoping if it is just a single proxy we can
> use the "WPAD" script to auto-detect the proxy address in the browser.

There are a number of techniques you can use to load-balance among
caches: WPAD (http://wiki.squid-cache.org/Technology/WPAD) is not
limited to single-cache scenarios. In addition you can use DNS-based
load balancing or an external NAT-based load balancer such as Linux
Virtual Server.

>    If a single server can support more than 3500 users then what kind
> of specs it should have? (i.e Processor, RAM, HDD Space, RAID level
> etc)

See my previous remark about number users being a meaningless
indicator of performance.

>  Also I need advice from the Pros who run setups with this much number
> of users. Advance thanks for your replies.

I guess that the first step is collecting some more relevant data:
some info can be found on
http://wiki.squid-cache.org/KnowledgeBase/PerformanceAnalysis and
http://wiki.squid-cache.org/PerformanceMeasure

Thanks

-- 
    /kinkie