I'd like to tell you a story.
I'm running a Minecraft server for a community since nearly two years, and we have been facing a lot of problems during this long time.
For those who don't know Minecraft, it's a game where there is no real goal, you can play in multi-player, break things and make the world as you want with blocks. It's fun, and special.
The bad thing in Minecraft is that it's all coded in Java, even the server side. Minecraft server eat all your memory, your disk bandwidth, your disk space, your network and ONE CPU (yeah, it doesn't run on multiples CPU).
First, we had a tiny RPS (Real Private Server, which was a real machine with a network disk). We could barely have one Minecraft server with more than twenty players. One day, without warn, we had a crash with our Ext4 /home. It was difficult to backup because a Minecraft Map could make a few gigabytes split in thousands of files. We were doing backup by ftp at a slow speed to reduce the server disk usage. It was a pain!
Then, we switched the server to a new one, quad core, sixty gigabytes of ram and two terabytes of disk. This time, I chose FreeBSD because I knew that it would work greatly ! Linux could have worked too, maybe we could have more performance, but it would not be as easy to manage as our FreeBSD box.
With ZFS snapshots, we backup our map every hour. In case of BIG CRASH, we can restore everything quickly. Java is working very fine on the server side, the server never crashed, even with two Minecraft server on (each server is using 7 Gb of memory). We are also using compressed ZFS pools for the maps, it reduces the load drastically.
I just can't imagine how to do this with another system. How could I save the map without disk latency on our server? We are also running a lot of daemons like "Mumble" for multi-player VO-IP, lighttpd as web server with php-fpm and lisp web server.
We were also available when the leap-second bug occurred the 2th of July, where a lot of Linux systems were overloaded due to a bug causing Java or Mysql to take all the cpu.
With FreeBSD, we don't know any software limitation for the things we need.