Backup means not only backing up data on disks. Backup also means verifying that backup media contains valid data that can be used to restore the system, as well as providing replacement parts for disks, power supplies, software disk media etc.
Do not schedule any batch jobs in M3 Business Engine during the backup of the entire database!
Backup of disk data is utterly important. Make sure you have understood the backup needs of SQL Server databases, for more information, see M3 Business Engine and Microsoft SQL Server - Best Practices (SQL Server BPG) on Xtreme Documentation Portal. You must also define a backup and recovery plan, and practice recovery from backed up files.
Also make sure that you have fast access to spare parts like disks.