Friends,

Need some guidance.

memory usage according to Grid Control is >95%. Oracle should be using 50% not 95%. I need to know what in oracle is consuming 95%

what is eating up all the memory?


free output
total used free shared buffers cached
Mem: 4041428 3945060 96368 0 147664 2206852
-/+ buffers/cache: 1590544 2450884
Swap: 8345656 42008 8303648


top output
Tasks: 223 total, 1 running, 222 sleeping, 0 stopped, 0 zombie
Cpu(s): 1.0% us, 1.7% sy, 0.0% ni, 94.9% id, 2.4% wa, 0.0% hi, 0.0% si
Mem: 4041428k total, 3932916k used, 108512k free, 147668k buffers
Swap: 8345656k total, 42008k used, 8303648k free, 2206984k cached

Linux preallocates most memory to buffers/cache so you'll always see a high memory utilization in free if you look at the first line.

However if you look at the "-/+ buffers/cache" line you'll see what is used/free without the buffers/cache. This is your ACTUAL memory used/free. Looking at what you posted I don't see a memory constraint.

Look at the output after buffers/cache. Seems to me you have 2.2G free memory.

In short, Linux is pretty advanced kernel, and it has "free memory is wasted memory" philosophy. So, it uses almost all free memory to cache stuff. Cached memory is free. It takes virtually no CPU time to give cached memory to program, it's like it is not used at all.

Anyway, always look at the output after -/+ buffers/cache, and search the Internet if you want to know more about Linux memory managment (which is the best as the current computer science can provide).

EDIT: jlightner answered while I was typing this (I'm sleepy after work, so I type with ease ). Gotta love LQ

Thank you for the prompt reply along with the explanation.

what would be your suggestion to me for monitoring the threshold
suppose i want to be notified when memory usage is above 75%
do i keep track of -/+ buffers cache.

Thanks again

That's what I do. My monitoring is based on the +/- buffers/cache.