How does NetBackup select images for duplication?

[rjrumfelt]

Does anyone know how NetBackup selects its images for duplication via vault profiles?  I'm not talking about how to set up the selection criteria, but once you have set the desired criteria, within that framework, how does NBU choose which image to duplicate first.

Say that I have my profile set to look back between 14 and 7 days since the backup occurred.  Are the images between that time frame randomly selected?  The behavior that I would like to see is the oldest image get duplicated first, however that is not what I'm seeing in practice, so I was curious of the internals as to how that selection takes place.

[julies · Accepted solution]

Vault admin guide page 90, table 5-8 states selection options for detail.

According to the Guide, By default, Vault duplicates images from largest to smallest, which improves tape drive utilization during duplication and duplicates more data sooner.   

By default, Vault duplicates tape images using the time the backup was created.  It duplicates images from the oldest to the newest.

[rjrumfelt]

Thanks.  I should have caught that.  So since we're duping from disk, there doesn't appear to be a way to change that behavior. 

Thanks.