If your server has a lot of accounts or is overloaded Cpanel`s cron started backup doesn`t work. In this case set up your own cron job or log in and create a backup manually from shell. Here is how to do it:
touch -B 170000 /backup/cpbackup/daily;nohup nice -n 19 /scripts/cpbackup &
Wait a second to let it start. Then press enter. Now it should go back to the shell where you can enter commands. Enter top. Then press i. Now you should see all the processes that are currently running. You should now see either rsync or pkgacct processes. That means you started the process successfully. Press q to leave top. Then type exit to log out. The backup will keep running in the background. Preferably start the backup so that it will not run during peak business hours.
You can also set up a cron job to execute the command above. For some reason it is much more reliable then Cpanel`s cron command.
The touch command doesn`t work with all versions of touch. On some servers you got to do:
touch -t 05050505 /backup/cpbackup/daily
PLEASE NOTE: Canel does suspend the creation of backup if the load is above the load you specified on WHM for log file processing to be suspended (backup will be resumed later but only if the load goes down). At least it used to be like that. I`m not sure if they still do it that way but I pretty much do think so. Make sure you set this value to a higher number. By default it is 0 so the load can be 1 or 2 depending on the amount of CPUs which is usually not enough because most servers have a higher load even if they are not overloaded (i.e. because cron jobs are all run in the same second which will increase the load but the server will be idle again a second after this so the load doesn`t really mean that much).