How to count dropped connections

[Amos Shapira]

2009/6/9 shimi <linux-il at shimi.net>:
> At what layer do you define "dropping a request" ? Not accepting a TCP
> connection (4) ? Failure to  complete the request from the reverse proxy to
> the backend servers (HTTP error) (assuming you have backend servers - the
> network structure is not obvious from your original message)?

We use Linux Virtual Server (LVS) in DR mode (i.e. packets come in to
a virtual IP through the LVS, outgoing replies are sent directly from
the Real Servers) in load-balancing (i.e. multiple servers accept and
handle requests in parallel).

Some of the Real Servers are configured as "persistent", i.e. all
requests from same client within a two-minute period will be handled
by the same Real Server, due to functional requirements, others don't
have this requirement.

>
> What answers the TCP requests to port 80?

All requests are handled by Apache 2.2 modules written in C++.

>
> Do you use efficient HTTP handlers already, e.g. Lighttpd or even better,
> nginx? :)

We looked at it (lighttpd) and back then didn't see a justification to
make the switch (already had in-house knowledge to write Apache
modules vs. another learning period to take with lighttpd, plus
Apache's flexibility back when we didn't know what we'll need was a
factor, e.g. we also had php, perl and CGI code running around at the
beginning).

As far as we can tell the bulk of the load is inside our own
home-grown module, not inside Apache.

What I'd like to know is how many failed connections clients receive,
be it "connection refused" or time outs.

Hope this answers the questions.

Thanks,

--Amos