High Memory Utilization
Hi,
There are some production servers for LDAP (OpenLDAP) that we have in place. I see that Memory (RAM) utilization remains constantly above 90% on all of them. We also have had alerts stating high time being taken for LDAP Authentication. I also find that Swap utilization at the same time is very nominal or not at all. So, how do we measure and determine that a certain level shows an "optimum usage" of Memory / RAM and beyond which an investigation is required? Any guidelines for specifying these levels of alerting/monitoring: Load Average or CPU Utilization: Memory / RAM Utilization Swap Memory Utilization and other such essential or critical aspects from the monitoring / alerting and administrating point of view? |
That sounds like the typical misunderstanding of Linux ram stats, which the following page was written to explain
http://www.linuxatemyram.com/ Quote:
In your current situation, I expect free+buffers+cache is a large fraction of total ram. If that is true then there is no memory pressure worth worrying about. The low swap utilization also indicates lack of memory pressure, but a high swap utilization doesn't necessarily indicate significant memory pressure. What matters with swap is how often pages are read back in. When free+buffers+cache adds up to less than 30% of total ram and there is significant use of swap space, it becomes harder to determine whether that indicates real memory pressure. |
to check the amount of RAM is really available now, run this:
Code:
free -m Code:
georges@w520:~$ free -m Now to diagnose your performance problem, you can use those commands: Code:
top There are other tools, but I would start with those two And also, you should check your DNS resolution on that machine. Many machines are set to use a dns server that is unreachable, and then lots of network transactions take an additional 5 seconds because the machine waits for a timeout of its reverse DNS request. please post the result of Code:
cat /etc/resolv.conf |
Quote:
|
All times are GMT -5. The time now is 01:16 AM. |