For our Magento users this is a common error that causes the site to become unresponsive.
As the error message states: Write error saving DB on disk: No space left on device
It is due to not having enough drive space on the server.
You can easily check by running from the CLI:
As Magento loves to suck up drive space with log files, and of course normal usage of product additions, not having not enough space can cause your server to become unresponsive.
Best to reserve at least a third of free space available to your server to make sure everything runs smoothly.
How to increase an EC2 volume? Right here >>