Understanding NetBackup image copy numbers...

[jaromolson]

I am trying to grasp how the process of enumerating the backup image copy number is handled in NetBackup.  Specifically in the following case:

Storage LifeCycle Policy

 - Backup to PureDisk Disk Storage Unit (Copy 1)

 - Duplicate to PureDisk Disk Storage Unit (DR Facility) (Copy 2)

Then I setup a Vault process that looks at my Copy 1 images on PureDisk and runs a vault to offsite tape storage.

Is the vault process then listed as copy 3?

If my Vault job runs before my duplicate copy to Pure Disk Storage Unit (DR) runs, do my copy numbers enumerate as follows:

 - Backup to PureDisk Disk Storage Unit (Copy 1)

 - Vault to offsite tape - (Copy 2)

 - Duplicate to PureDisk Disk Storage Unit (DR Facility) (Copy 3)

OR

Am I not understanding the process and there is a copy 1 for the backup and then the Duplicate to PureDisk (DR) and the Vault to offsite tape both listed as copy 2?

Final question:

At what point is the image enumerated, at the time the duplicate job kicks off or at the conclusion of the job?

Thank you in advance for any answers to this question.

[Nicolai · Accepted solution]

In Netbackup copy numbers are sequential, each new copy get is own copy number that is retained during is's lifetime. Expiring a copy does not "re-arrange" the copy numbers. Restore is always carried out from copy number 1 also know as the Primary copy. You can change the primary copy with the bpimage command.

As you have observed changes in the copy schema will result in different copy numbers. Using Netbackup Storage Lifecycle Polices is designed to handle multiple duplication and will secure each duplication is completed before the next start.

Hope this answers most of the questions.

[watsons]

You can always refer to the output of bpimagelist -L <backupID>.

Nicolai has explained how the number goes. 

Additional note, if you expire a primary copy (let say copy1), it's going to make the next copy to be primary automatically.

[David_McMullin]

And, if you backup to disk as copy #1, then duplicate to create copy #2, then expire copy #1 =

copy 2 is automatically moved to primary. no copy 1.

If you then copy #2 you get copy #1, and unless you specify, #2 is primary until it expires, then copy #1 will be!

So - the copy numbers increment - but will fill in lower numbers if they are expired.

I believe the copy number is assigned at the start of your copy.

If you use SLP it is easier to control the timing of the duplications.

You will never have 2 unexpired copies with the same copy number.