I ran in to a problem with the VBK file size of a Veeam backup Job (running Veeam B&R 6.5). It didn’t fit on tape anymore. So I split up the Job into two different Jobs. One with important VMs and one with less important VMs. The important VM backup job goes to tape, and the other one stays on disk.

But after I deleted the VMs from the Job my VBK file size didn’t get any smaller. It was only growing. That was not what I expected.
So I contacted Veeam support and they pointed me into the right direction. See http://helpcenter.veeam.com/backup/70/vsphere/index.html?retention_deleted_vms.html

There is a Delete VMs date retention period. Default its configured at 14 days. See explanation and screenshot below.

In the VM retention section, specify the number of days to keep backup data for deleted VMs.  When a backup job starts, Veeam Backup & Replication checks the list of VMs included in the job. If a VM is no longer available (for example, it was deleted or moved to another location), Veeam Backup & Replication will keep its data in the backup for the period you specify in the Deleted VMs data retention period field. When this retention period is over, data of the deleted VM will be removed from backup files.

The retention period for deleted VMs is particularly useful if the job is configured to create synthetic full backups, and you want to make sure that the full backup does not include redundant data.
This was an option that I didn’t know it existed. So I changed this to 3 days, and indeed the backup job shirked. Problem solved, the Veeam job fits on tape again.

** Edit 14-02-2014, updated Veeam link to the new location. Thanks Cor for pointing that out.

Disclaimer.
The information in this article is provided “AS IS” with no warranties, and confers no rights. This article does not represent the thoughts, intentions, plans or strategies of my employer. It is solely my opinion.