Adam Sweet's Wiki

Taken from http://bergie.iki.fi/blog/if-your-apache-ever-runs-out-of-semaphores---/

If you get this error message when trying to start Apache, then you're out of semaphores:

#apachectl start
Ouch! ap_mm_create(1048576, "/var/run/httpd.mm.22903") failed
Error: MM: mm:core: failed to acquire semaphore (No space left on device): OS: Invalid argument
/usr/sbin/apachectl start: httpd could not be started

The easy fix is to just remove all semaphores owned by Apache:

# /usr/bin/ipcrm sem $(/usr/bin/ipcs -s | grep apache | awk '{print$2}')

Got the fix from cacti forum.