Re: maximum connections

Chuck Pitre wrote:

> I'm about to put up our transparent proxy server however i am
> a bit worried about squid puking with a few hundred simultaneous
> connections?? (I currently have a total of 600 + some dialup ports)

You need to make sure that your OS supports enought file descriptors and
sockets and that you have enought of memory available. You should have
minimum 2000 filedescriptors and 1000 sockets available in a
configuration like this, preferably the double or more.

Figures that may help you make a calculation:

* Each active browser user may use up to 4 TCP connections
* Each TCP connection uses up to 3 filedescriptors of which 2 are
sockets (one incoming socket, one outgoing socket and one cache file).
* TCP may require up to 32KB of memory for each active TCP connection
(TCP send/receive + IP defrag buffers).
* Squid requires about another 32KB of memory for each active
connection. More if the user fetches large objects.
* Quite a bit of memory is required to keep track of your cache. See the
FAQ. The guideline is 100 bytes / cached object, but calculate with 200
to be on the safe site.. A estimate of the number of cached objects is
total cache size / 13KB.
* Your OS should have some memory available for disk I/O buffers.

I would not recommend you to activate transparent proxying for all ports
at once, but begin with 25 or 50% to see if your estimate of the
resource requirements is correct. You should also be warned that there
is a number of sites not working well with proxies.

You should also take care to configure quick_abort in squid.conf
properly.

---
Henrik Nordstrom
Spare time Squid hacker