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I have a memory usage problem with my Checkpoint Firewall (it's a physical firewall).

On my monitoring software OPManager I can see that 94% of my memory is used.

In SSH, when i enter this command : TOP.

I can see this :

Mem:   4138776k total,  3879220k used,   259556k free,   348976k buffers
Swap:  9992388k total,        0k used,  9992388k free,  2777396k cached

So my monitoring is true, but when I sort the processes by memory I don't see which processes are using so much memory.

You can see the top screenshot here:


I do not understand how my firewall uses memory. Can anybody help me?

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marked as duplicate by Tom O'Connor Aug 7 '13 at 10:29

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Should I ask why your firewall has 22 Apache children running? – Ladadadada Aug 7 '13 at 8:34
@Ladadadada Because there is a web based management interface for my fw – Adeel ASIF Aug 7 '13 at 8:37
I'd be surprised if your web based management interface needs to serve 22 simultaneous requests. 4 children would probably be more than enough. I'd also be surprised if it need to run the prefork MPM. It's using 10% of your RAM. – Ladadadada Aug 7 '13 at 8:44
If it's working, I don't see why you should care, other than it's working. – Tom O'Connor Aug 7 '13 at 10:28
up vote 4 down vote accepted

Linux kernel is just doing its job and effectively caching stuff to RAM instead of reading it from the disk every time. Your server has 4 GB of RAM, and only about 700 MB is being used for applications. Around 3 GB of RAM is in use for caching and buffers (which can and will be discarded very quickly if any program suddenly needs more RAM), and about 256 MB is completely free.

Free memory is not effectively used memory! See Linux ate my RAM.

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