After updating your OS or APC Pecl module, you probably noticed this in your Apache log file :
PHP Warning: PHP Startup: apc.shm_size now uses M/G suffixes, please update your ini files in Unknown on line 0
As mentioned, size values must now be specified with suffix :
M = Megabyte
G = Gigabyte
To correct this, simply edit :
/etc/php.d/apc.ini
And the following parameter :
apc.shm_size=256
Must now be written as :
apc.shm_size=256M