I am running my linux application that receives client connection and opens
a connection to a server. I have 3GB RAM and dual CPU.
I manged to support 200,000 (!!!) concurrent connections to my aplications, meaning I open 400,000 sockets (200,000 to clients and 200,000 to servers). This all work fine.
When I try to increase the cuncurrent connections my device freezes up
and I get this error "bash: fork() error . Cannot allocate memory".
And I must reboot the device.

I changed the /proc/sys/fs/file-max to more than 800,000 to allow file-descriptors.

Is there anything else I need to do?
Why do I get stuck around 200,000???
Any Ideas?
Thanks
E.

What makes you think you can support more than 200,000 connections? And *WHY* do you want to? In any case, the error said nothing about file descriptors, but about memory. You are out of virtual memory, most likely.