Re: [squid-users] httpd accelerated server config questions

From: Henrik Nordstrom <>
Date: Sat, 31 Mar 2001 14:57:11 +0200

Einar Bordewich wrote:
> One of our hosting customer has a publishing solution based on PHP4, running
> on a dual PIII 700 1Gb RAM. From time to time there is extremely high load
> on one of the virtual domains, making PHP chew memory. The data is
> generated dynamically, but it's realy static data, changed 1-4 times a day.

Good candidate for caching then. Even more so if you modify the server
to include proper expiry information indicating the approximte time of
next update.

> Regarding this, we have configured an squid httpd accelerated server planing
> to put this in front of the individual domains. For now, we have only dummy
> tested against temporarily sites. Seems to work excelent!


> Is there any software available to stress test the squid?

For large scale stress tests there is polygraph, but it is more intended
for proxy testing than accelerator testing.

> Any tips on how to configure the apache server best way?

Shouldn't need much special tuning.

> Any tips on how to best configure squid for caching timeout 5 to 60 minutes?

See refresh_pattern, but the best way is to make the server indicate the
caching time using the proper Expiry/Cache-Control HTTP headers.

For an accelerator you might also want to tune the READ_AHEAD_GAP to
make the accelerator more aggresivle suck content from the backend
server, thereby finishing the server request quicker. This define
controls how much data Squid buffers when forwarding a reply from the
origin server to a client. Defaults to 1<<14 (16K) + TCP windows.

> We want the httpd accelerated server to cache for the backend server(s), is
> this entry needed: httpd_accel_with_proxy on

No and yes. It is not really needed for accelerator operation, but
HTTP/1.1 standard requires it to be turned on as HTTP/1.1 servers MUST
accept fully qualified URL's for compability with future HTTP versions.

Note: you must have proper access controls limiting what the accelerator
might be used for if this or httpd_accel_uses_host_header is enabled, or
else it becomes trivial to abuse your accelerator as a proxy.

My recommended setups always have both enabled and proper access
controls, but then I like to have generic but perhaps slightly more
complex setups that is trivial to expand later on when needed..

Henrik Nordstrom
Squid hacker
Received on Sat Mar 31 2001 - 05:59:01 MST

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