There are several important things you should consider backing up on a Linux system in order to be able to recover from a disaster or failure. Here are some key areas to consider:
System files and configuration: This includes important system files such as the kernel, system libraries, and system utilities, as well as configuration files for the operating system, applications, and services.
User data: This includes personal files, documents, and other data that is stored in user home directories or other locations on the system.
Databases: If you have databases installed on your system, it is important to back up the database files and any associated configuration files.
Software packages: If you have installed additional software packages on your system, you should consider backing up the package files and any associated configuration files.
Boot files: These include the bootloader configuration files, as well as the kernel and initial RAM disk (initrd) files.
By regularly backing up these key areas of your Linux system, you can ensure that you have the necessary data to recover from a disaster or failure. It is also a good idea to test your backups regularly to ensure that they are working as expected and that you can restore from them if needed.