[K12OSN] What hardware for Squid/Dansguardian?

[Sean Harbour]

A P3-700 will typically handle at least 400 students, correctly configured. It may choke if there is a lot of multimedia going through it.

A dual Xeon 2.8Ghz will handle several thousand, given enough RAM and fast SCSI drives.

Memory is the most important, followed closely by CPU then disk speed.

An adequate system that is crippled by low memory and slow hard drives will not perform acceptably.

An adequate system with enough ram and a slow hard drive will work okay.

Given a choice, I would put more RAM in a proxy cache vs faster hard drives.

128 MB is not enough for over 50 users, 256 MB over 200 users, 512 MB over 400 users typically. YMMV, but this is a good rule of thumb.

The top and sar commands are your friends. Make sure that the maximum memory in use is not maxed out within minutes. If the system load
is staying consistently over 3, you definitely need more CPU or to reconfigure your filter settings. I like to see the CPU load stay under .7 except during heavy load spikes, then I don't want it going over 1.5 if possible. 

There are some performance tweaks you can do to the system to optimize it.

You can adjust the cache to hold more/larger objects in memory to reduce disk load, or less/smaller to reduce memory footprint.

You can use a fast lookup optimized file system such as reiserfs for a small disk performance boost.

You can change the filtering parameters. Just changing the phrasefiltermode setting in dansguardian.conf can half the cpu usage with very few downsides.

In short, a 500 Mhz PC, with 256 MB RAM and a 10 GB IDE hard drive should perform adequately as an internet filter for a facility with around a 100 students total on a 512Kb Dsl circuit . A 1 Ghz PC with 512 MB RAM and a 40 GB IDE hard drive should handle around 400 students adequately on a 1.5 Mb T1 circuit . A dual 3 Ghz Xeon with 2 GB RAM and several 10000 rpm SCSI drives should be able to handle several thousand students with a 10 Mb circuit fairly well.

For home use with dansguardian, I have seen acceptable performance with a dedicated Pentium 200 with 180 MB RAM on a cable modem, but some latency was noticeable. Latency was almost unnoticeable with an AMD 500 and 256 MB ram.

Of course, these parameters can vary widely from situation to situation, but they should at least get you into the ballpark.

Sean Harbour
sharbour at nwresd.k12.or.us




>Fortunately we have a local vendor who gave us an excellent ($1700)
>price on a dual 2.8Ghz Xeon small server/graphics workstation box that
>they had, which has worked out great for us.

>My hypothesis is that the single processor setup simply couldn't keep up
>with the heat generated by doing so much work on the single unit, where
>the dual processor setup spreads the load/heat around enough that the
>fans can keep up.

>Of course I don't have any "technical data" to back this hypothesis up
>(besides the fact that the new proxy hasn't had a problem since we put
>it in), so your mileage most likely will vary.



On Thu, 2005-05-19 at 00:07, Robert Arkiletian wrote:
> What hardware is more important for a caching/filtering proxy server
> that runs Squid/Dansguardian for a school of ~300 internet
> connections.
>
> I'm thinking from most important to least
>
> 1) hard disks
> 2) memory
> 3) cpu
>
> Anyone agree/disagree? What min. sys. req. would people recommend?
--
Jonathan S. White
Computer Technician
Shaker Regional School District
jwhite at shaker.k12.nh.us
(603) 267-9223
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