--snapshot={always|possible|none}
Defines whether to back up files directly (one by one) or by taking an instant data snapshot.
Available values of the parameter are as follows:
Create a snapshot if it is possible. Back up files directly if taking a snapshot is not possible.
Do not create a snapshot. Always back up files directly. Trying to back up files that are opened for exclusive access will result in a read error. Also, files in the backup may not be time-consistent.
Always create a snapshot. Using a snapshot enables the backing up of all local files. This includes files opened for exclusive access. The files will be backed up at the same point in time. If a snapshot cannot be taken, the backup will fail.