Stability problems

Requirements:

If there is a problem with the stability of your Dedibox (for example, it crashes often), you should do some checks of your server.

  • Check that your operating system and the firmware of your server is up to date and in “Stable” version
  • Check the use of your RAM dedibox via the command “free -k”. If there is massive use of the SWAP of your server, we recommend that you check the configuration of your software.
  • Run a server hardware diagnostis through your management console.
  • If the hardware diagnosis reveals no defect, we advise you to complete this test with memtest: stop all running programs on your dedibox then launch the software 'memtest' with parameters 'all 4' (if this does not pass, specify the free memory in a parameter)

Known problems with Debian unstable and Ubuntu dapper can cause crashes your dedibox. Install a Dedibox Kernel to solve this problem.

High CPU load

In a first step, you need to check which process causes the problem.

The commands top & htop can be very useful in this case.

htop is not installed by default on most distributions. You have to install it manually.
Example for Ubuntu/Debian: sudo apt-get install htop

These software will list the processes and show you the top consumers.
This can be a normal load (eg your site is very popular), but can also be a problem.

In the second step, you have to check if your server is using the SWAP partition.

It will be used by the server, if it does not have enough memory (RAM).
The SWAP is on the hard disk, it can increase CPU usage via I/O wait.
If you have completely used up your RAM, it can also be a configuration problem or a server undersized for your need.

To verify it:

free -mh
             total       used       free     shared    buffers     cached
Mem:          3,8G       3,4G       325M       529M        44M       869M
-/+ buffers/cache:       2,5G       1,2G
Swap:         3,9G       1,6G       2,3G

In this example we can see that 1,6GB of the SWAP is used.

Finally, check and optimize the configuration of your software, if it is not done already.
This can sometimes have a great impact on the resources used by the server.