Question: My database server is timing out because MySQL seems to hang once it has used up 4GB of RAM, even though the server is equipped with 6GB. How can I make MySQL take advantage of the full 6GB available?
Answer: If your current server setup involves a 32-bit architecture or even just a 32-bit version of your operating system, the short answer is: you cannot. By design MySQL will not be able to use more than 4GB unless it is running on a 64-bit OS.
If you are running Linux, type ” uname -m ” from the command line to see whether or not you are using a 64-bit version. If you know for a fact that your server actually has 64-bit processors, you can reinstall Linux with a 64-bit kernel.
The other less-drastic measure you may be able to take is to install a PAE (Physical Address Extension) kernel, which will allow your server to access physical address space larger than 4 GB. Some distributions, such as CentOS offer PAE kernel packages that you can easily install.