htop Memory meter is full. I haven't even started any service yet

I don't understand why my htop meter is full already. I'm not even running some task. Here's the screenshot of my htop:

The green meter shows used memory, the blue meter shows buffers, the yellow meter shows cache. it seems that the cache have used up all my memory here. Or am I just confused? Because the numeric number shows 48/494MB.

So what is happening here? Should I increase the memory of my server?

I'm going to run nginx, php and wordpress. is this server enough to handle this setup?

Solution 1:

Since you weren't using your memory for anything better, its being put to use as disk cache. If you start services, they will just take memory from the cache. This is a good thing, not a sign that anything is wrong. See linuxatemyram