We noticed over the last few days that the BAMStarSchema database backup was producing erratic sizes. There were no running instances on the BizTalk Group at the time, but every other backup's size would be larger than the one inbetween. For example:
Backup #1 - Size 5MB
Backup #2 - Size 10MB
Backup #3 - Size 5MB
Backup #4 - Size 7MB
Backup #5 - Size 5MB
Backup #6 - Size 8MN
Backup #7 - Size 5MB
Backup #8 - Size 7MB
And so forth. The obvious commonality was the regular size at every other backup being 5MB. After some investigation it turns out that if the BAMStarSchema backup occurs as precisely the same time as when a BAM DTS Job is running then the backup size is greater. In the case above, a SQL Job was calling the DTS Job at regular intervals that just happened to cause the pattern.
According to the MS documentation at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/operations/htm/ebiz_ops_backuprestore_zsbv.asp If you are using Business Activity Monitoring (BAM), verify that neither the BAM cube process nor data maintenance Data Transformation Services (DTS) packages are running when the backup package is scheduled to run.
Therefore, we will need to modify our backup job to ascertain that no BAM DTS packages are executing at the same time. As our particular BizTalk set-ups are configured to act as a service for potentially many applications that could conceivably include BAM activities then the job will have to loop through and disable these prior to executing and then re-enable them on completion.