What are semaphores and how are they caused? has a fairly good explanation of what semaphores are, but I'm not sure what my configuration should be. I recently ran into the same problem as that question, and when looking over the internet I found wildly different examples of what the new config should be. Here's a couple of examples:
On RHEL 7.2:
# cat /proc/sys/kernel/sem
250 32000 32 128
On Fedora 20:
# cat /proc/sys/kernel/sem
32000 1024000000 500 32000
Those are some crazy different numbers. What makes sense for a medium size server, and what are the downsides to larger numbers?