1 - metadata corrupt : is contain all of data that are in backup files full or incremental such as mp3,dat.
No, metadata is related to the backup files. This can get corrupted due external factors for example. As said before you can't predict this.
2- vm data block corrupt : each of vm backup file has contain many data block
A VM contains data blocks which we save. If one or multiple of these get corrupted in the backup file we will try to recover it in a new backup file (can be full or incremental). This can also be related to external factors. Again we can't predict this.
in documaind said : At the end of the backup job session, Veeam Backup & Replication performs the health check
when i enable perform health check it will automatically run health check after every backup ?
4. in document said : If the health check detects corrupted data, Veeam Backup & Replication completes the backup job with the Error status and starts the health check retry process. The health check retry starts as a separate backup job session.
what does means from that? the health check is running and detect corrupt data thus why said if health check detect corrupt data start health check retry process?
We will finish the backup job as stated. Then the health check runs and it will complete giving you an error status so you are aware of it and that the file is corrupt and we will try to recover it.
5 -in document said : If the health check has detected corrupted backup metadata in the full backup file :
During the health check retry, Veeam Backup & Replication transports data blocks of the whole VM image from the source datastore, creates a new full backup file on the backup repository and saves transported data blocks to it.
i could not understand means from "transports data blocks of the whole VM image from the source datastore, creates a new full backup file on the backup repository and saves transported data blocks to it. "
is that means if detect corrupt data for full backup delete full backup from repository and get a new full backup ?
It means that if we detect corrupt blocks we get the correct data from the source datastore to create a new full backup file.
6 - in document said "If the health check has detected corrupted backup metadata in the incremental backup file"
During the health check retry, Veeam Backup & Replication transports incremental data relatively the latest valid restore point in the backup chain from the source datastore, creates a new incremental backup file on the backup repository and saves transported data blocks to it.
is that means if detect corrupt incremental backup file will that delete all incremental backups from corrupted and then get new incremental backup ??
No, we will only delete the incremental which is corrupt and try to recover it in a new file. This is the same process as with a corrupt full backup: get the correct blocks from the source and recreate an incremental backup file.