Question

Why CentOS droplet uses so much memory?

  • Posted April 11, 2014

I use digitalocean 512 Mb droplet, with centos 6.4, 32bit. I call

top -b -n1

and see that I have only 64Mb of free memory:

Mem: 510888k total, 446184k used, 64704k free, 141832k buffers

OK, I have installed OpenVPN, but it eats only 0.5%, according to ‘top’, the rest is consumed by the system and programs, which were pre-installed.

Well… may be 512Mb is a bare minimum and I should not ask for a lot, but then I create a 1 Gb droplet, with centos 6.4, 64bit, expecting to have additional 512Mb, but… when I call

top -b -n1

I see that there is only 192 Mb of free memory:

Mem: 1020400k total, 827804k used, 192596k free, 24832k buffers

Again, it is a clean system, nothing is running on it yet.

I am also using vps from another provider and the same 1 Gb CentOS 6.4, 64bit gives completely different memory picture:

Mem: 1048576k total, 278932k used, 769644k free, 0k buffers

So, what is wrong with memory usage? Is it possible to do something, to have at least 512 Mb free on a 1Gb droplet?

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Thanks to everybody, who replied. I have no idea what have changed, but 1 minute ago the top command produced completely different results on my droplets. For 512Mb droplet I got <br> <br>Mem: 510888k total, 56972k used, 453916k free, 5988k buffers <br> <br>and for 1Gb droplet I got <br> <br>Mem: 1020400k total, 85708k used, 934692k free, 5772k buffers <br> <br>as you can see the picture changed completely (may be admins heard my cry?)) ) <br> <br>Kamal, for 1Gb droplet your “free -m” gives <br> <br> total used free shared buffers cached <br>Mem: 996 83 912 0 5 31 <br>-/+ buffers/cache: 46 949 <br>Swap: 0 0 0 <br> <br>But anyway, the output from “top” also looks better now. <br> <br>Again, thanks to everybody for the link linuxatemyram.com ))

What’s the output of this command? <br> <br><pre>free -m</pre> <br> <br>It’s possible that the OS is using free memory for disk caching. <br> <br>See <a href=“http://www.linuxatemyram.com/”>Help! Linux ate my RAM!</a>.

Linux uses free memory to cache things. This does not slow things down, and you can still use that RAM. See linuxatemyram.com for a more thorough explanation of what is happening.