Veeam Backup & Replication automatically retries several operations that are performed within a backup copy job sessions.
Job Tasks Retry
By default, Veeam Backup & Replication automatically retries a failed backup copy task 5 times within one backup copy job session. A new task is started immediately after the previous one, without any interval.
The backup copy task is retried only if the previous task has failed and a restore point has not been copied to the target backup repository. Veeam Backup & Replication does not perform a retry if a task has finished with the Success or the Warning status.
The backup copy task is retried during the same backup copy interval only. If a restore point fails to be copied during all retries in the current backup copy interval, Veeam Backup & Replication marks the synchronization task as failed and waits for the expiration of the backup copy interval. After that, Veeam Backup & Replication performs the necessary transform operations and starts a new backup copy interval.
A backup copy job can process several VMs. If only some VMs are successfully processed by the backup copy task, Veeam Backup & Replication creates a restore point holding data for these VMs on the target backup repository. Veeam Backup & Replication will attempt to process restore points for all VMs during the next backup copy interval.
Some errors from WAN accelerators can block backup copy job retries. For example, if there is no space in the global cache on the target WAN accelerator, Veeam Backup & Replication put backup copying operations on hold and wait for the expiration of the backup copy interval.
After the backup copying task, Veeam Backup & Replication performs a number of additional transform operations on the target backup repository if necessary. These operations include the backup chain transform, removing of deleted VMs from restore points and compacting a full backup file. For more information, see Backup Copy Job.
Veeam Backup & Replication may fail to perform transform operations for some reason: for example, if the backup file on the target backup repository is locked by the file-level restore session. By default, Veeam Backup & Replication automatically retries transform operations for 5 times. The first interval between retries is 1 minute; the interval doubles with every new attempt. If Veeam Backup & Replication fails to perform transform operations during all retries in this backup copy interval, the job is put to the idle state, waiting for the new backup copy interval to begin.
Virtual Infrastructure Access Retry
At the beginning of every backup copy interval, Veeam Backup & Replication accesses the virtual infrastructure to make up a list of VMs processed by the job.
Veeam Backup & Replication may fail to access the virtual infrastructure for some reason: for example, in case the Hyper-V host is not responding. By default, Veeam Backup & Replication automatically retries access operations for 5 times with a 5 minute interval.