Best Practices - Suggestions Request

[Anup Shukla]

Hi All,

We have been running varnish for over a month on our production servers now.
We are using the default configuration with a small change, that is to 
cache request with Cookies.

We have a number of web servers behind a load balancer, each web server 
running varnish + apache.

I understand that running both services on the same server is probably a 
bad idea, but due to time constraints i had no option but to go ahead 
with the current setup.

The problem is, the varnish process dies every 7 - 10 days, and i have 
to manually restart it.
One solution would be to write a script which monitors varnishd and 
starts it if not running.

I, however, would like to understand "Why it dies"... I have been 
monitoring the servers for long times at a stretch and it seems that a 
flood of requests for big files (100+ MB) seems to get varnishd down. I 
cannot be very sure about this though.

Is it really a bad idea to run varnishd on the same server with apache?

Another thing is, is it possible to configure varnish such that it adds 
a custom header to the response (for example, the ip of the server which 
processed the request or any custom value). This would greatly assist in 
knowing which server served the request.

Is it possible to make varnish refuse connections from the clients it it 
detects that the backend has stopped responding and start servicing 
again the moment it detects that the backend is up?

Sorry, if i have asked too many questions at one go.

Any help/pointers would be greatly appreciated.

Regards
A.S.