freebsd server limits question

[Eduardo Morras]

At 20:12 02/01/2012, Muhammet S. AYDIN wrote:
>Hello everyone.
>
>My first post here and I'd like to thank everyone who's involved within the
>FreeBSD project. We are using FreeBSD on our web servers and we are very
>happy with it.
>
>We have an online messaging application that is using mongodb. Our members
>send messages to "the voice" show's (turkish version) contestants. Our two
>mongodb instances ended up in two centos6 servers. We have failed. So hard.
>There were announcements and calls made live on tv. We had +30K/sec
>visitors to the app.
>
>When I looked at the mongodb errors, I had thousands of these:
>http://pastie.org/private/nd681sndos0bednzjea0g. You may be wondering why
>I'm telling you about centos. Well, we are making the switch from centos to
>freebsd FreeBSD. I would like to know what are our limits? How we can set
>it up so our FreeBSD servers can handle min 20K connections (mongodb's
>connection limit)?
>
>Our two servers have 24 core CPUs and 32 GBs of RAM. We are also very open
>to suggestions. Please help me out here so we don't fail deadly, again.
>
>ps. this question was asked in the forums as well however as someone
>suggested in the forums, i am posting it here too.

Is your app limited by cpu or by i/o? What do vmstat/iostat says 
about your hd usage? Perhaps mongodb fails to read/write fast enough 
and making process thread pool bigger only will make problem worse, 
there will be more threads trying to read/write.

Have you already tuned mongodb?

Post more info please, several lines (not the first one) of iostat 
and vmstat may be a start. Your hd configuration, raid, etc... too.

L