Have a look at the current location of the status file (e.g. /usr/local/icinga/var/status.dat) and the object cache file (e.g. /usr/local/icinga/var/objects.cache) and determine the size of both files. Add the size of the status file for temporary data (temp_file).

 #> ls -la /usr/local/icinga/var/
 -rw-rw-r--   1 icinga icinga 8.2M Jun 10 11:57 status.dat
 -rw-r--r--   1 icinga icinga 5.9M Jun 10 11:58 objects.cache

Increase the number to a considerable value to allow for future growth (100 MB should be sufficient in this case) and create the RAM disk.

	Caution
	If the value is too high then this will throttle your system because it will start to swap resulting in physical I/O once again.

 #> mkdir /var/icinga/ramdisk
 #> mount -t tmpfs tmpfs /var/icinga/ramdisk -o size=100m
 #> chown icinga:icinga /var/icinga/ramdisk

Adapt the values of user and group to the ones found in your configuration if necessary.

Add an entry to /etc/fstab to make the setting permanent so the RAM disk will be created automatically after the next reboot.

tmpfs                /var/icinga/ramdisk     tmpfs   size=100m        0 0

Edit the Icinga main configuration file and change the setting of the appropriate directives

 #object_cache_file=/usr/local/icinga/var/objects.cache
 object_cache_file=/var/icinga/ramdisk/objects.cache

 #status_file=/usr/local/icinga/var/status.dat
 status_file=/var/icinga/ramdisk/status.dat

 #temp_file=/usr/local/icinga/var/icinga.tmp
 temp_file=/var/icinga/ramdisk/icinga.tmp

Restart Icinga to put the changes into effect

 #> /etc/init.d/icinga restart