Very cool

It needs only one change when deciding whether to notify for WARNING or CRITICAL status:

————————
instead of:

if [ $MEMORY_USED_REAL_POURCENT -gt $WARNING ] && [ $WARNING != 0 ]; then
STATE=$STATE_WARNING

this line shall be like this:

if [ $MEMORY_USED_REAL_POURCENT -gt $WARNING ] && [ $MEMORY_USED_REAL_POURCENT -lt $CRITICAL ] && [ $WARNING != 0 ]; then
STATE=$STATE_WARNING
—————————-

Also, the value for size should be changed from Go to GB.