I am trying to figure out what is going with a backup job. I have a file server with a raw lun mapping in virtual mode. A backup to disk job that runs every night in incremental mode with synthetic full backups on Sunday and 21 restore points. As a secondary target in this job is a Tape job with one media pool for both full and incremental backups. On Thursday it is set to create virtual full backup which in my understanding does not happen due to the synthetic full. The media pool used for this job is set to create a new media set every Monday 12:00 PM and the retention policy is for 1 week.
What is happening is that every Tuesday the tape job writes to the tape random (as far as I understand) incremental and full backups. In particular at the time of writing the disk backups transferred to tape are, as they appear on the list of file to be written to tape, incremental backups from March 8, 10, 12, 11, full backup from March 13, incremental backup from March 14, 9 and 29.
I am not able to understand why all those backups are transferred to tape instead of today's incremental backup only.
Can anyone explain to me this behavior?
Thank you in advance,