Do I Need to Stop the Server Before Performing a Backup?

No. You can back up servers that are in use. When a server is running, data is written onto disks on the server, and some newly generated data is stored in the server memory as cached data. During a backup task, the data in the memory will not be automatically written onto disks, resulting in data inconsistency between disks and their backups.

To ensure data integrity, back up the server during off-peak hours when no write operation is performed on the disks. For applications that require strict consistency, such as databases and email systems, you are advised to enable application-consistent backup.