Hi, I run a minecraft server off a redhat server in a VM, and the past few days, I have been finding that something is eating my RAM! Im fairly new to servers in general, but after a few hours of googling, I noticed disk caching.

Anyway so long story short, i did free -m, and the output is:

Now I am fairly new to this as I say, but surely if it was the disk cache, the memory used for the Mem column and buffers collumn would be different. This suggests that it is a process. Now this is the strange thing, when i do 'top' command, i get this:

http://i54.tinypic.com/126fo88.jpg

Notice how the memory used is still far greater than what the processes use. The only thing I can think of, is that because I have screen installed, the server is opening twice for some reason, and that there is a second hidden javaw process. Anyway, please, I really need some help or advice on how to fix this. I have restarted the server many times, but I still find my memory usage is far greater than it should be when I start the java server!

Is this a VPS? What virtualization technology is your provider using? The only time I've seen 0 for buffers & cache is with .. OpenVZ, I think?

You have 441 MB free. I wouldn't worry about it until you get a lot closer to running out of RAM (I'd say until you start constantly swapping, but you don't seem to have any swap space .. another OpenVZ quirk?)

1 members found this post helpful.

Yes it is an OpenVZ redhat linux VM. Although I have 400mb free, I only have a 1gb guaranteed server, with 1gb burstable. I am just concerned about my server stability, and I have no idea what is taking up this extra chunk of ram! Could it be a ramdisk or something? I just want it fixed, because I was thinking of expanding and installing appache also.

It is perfectly fine for linux to consume all available RAM. It uses free RAM as CACHE, speeding startup of applications. You can check processes by "ps aux --sort rss" and see whats consuming RAM.

As you can see from the output of free, the OP's system is not caching at all.

Exactly my point! Something is using the RAM!

Anyone?

Here is an update:

http://i56.tinypic.com/68sz15.jpg

Getting worse :S

This is a type of virtualization that uses and reports memory very differently from a non virtual or ordinary virtual system. You don't have your own instance of Linux running inside virtual "hardware". Instead you have an environment that is restricted to seeing only part of what is running under an instance of Linux that you share with others.

So most of what you see online about diagnosing memory issues does not apply to your situation.

In the top program you should sort by the RES column to see what is eating memory. One instance of Java appears to be half the problem (based on what you already posted). So you need to investigate what you are using Java for. Since Java is a very general purpose tool, it is unlikely to be a problem with Java itself and likely to be a problem in some application you have using Java.

1 members found this post helpful.

That java instance is fine. It is the only process I want running on the server and I am fine with its RAM usage. I want the java instance to be taking up most of the RAM so the server is more stable. It is the other 1gb of RAM taken by another proccess that I want to kill

You seem to have ignored

Yes, but my point was, add up everything in the res column, and it does not equal the memory used at the top

Top shows not all running processes. If you sort by Res you may get a better view on what is using the memory.

Have you looked at the picture? The process does not show up at ALL on the 'top' command. Something is using up 1gb of pysical RAM and is not showing up!

Amunro -

Dude - you DON'T HAVE A MEMORY PROBLEM!!!!!!!!

And if you WANTED to "optimize" memory usage, the ONE process in question is Java.

Which, in your "top" output, is using 1.484GB virtual, and 860MB of resident memory.

You've got free RAM. You're using zero swap. Please LISTEN to what the others are trying to tell you. You have a Happy System. Relax. Chill

PS:
Two other suggestions to set your mind at ease:

1. As you've been told repeatedly, "top" doesn't show *all* processes - just the most *significant* ones. Here's a command to see all processes, sorted by Resident Set Size:
2. Investigate JConsole (or equivalent for your Java version):

1 members found this post helpful.