My Red Hat Enterprise Linux system shows that I am using a lot of memory, even though nothing is running. Why?

Issue

• My Red Hat Enterprise Linux system shows that I am using a lot of memory, even though nothing is running. Why?

• Is low free memory in Red Hat Enterprise Linux a cause for concern?

• My Red Hat Enterprise Linux server is using more than 90% of RAM (as reported by free). Should I be concerned about this?

• Our Service monitoring group was reporting false memory utilization alerts, as RHEL5.3 servers could easily reach 99% used memory.

• How can we better monitor the memory resources on the servers?

• What is a good metric to base memory shortage alerts on?