Removing a FULL tape which contains a full backup

[felonious_caper]

So, a cumulative backup only backs up information changed since the last full back up.

My question is lets say, i ran a full back up on monday every other week and cumulative backups run every day after that. If on the following monday, i remove a tape which contains last weeks full backup will the next cumulative backup write ALL the files or will it know even though the tape is removed what was changed since the last full back up.

[Kiran_Bandi · Accepted solution]

NBU verifies the timestamp/archivebit of a file to findout whether the file is changed or not from last full backup. Doesn't matter whether the FULL backup tape is available or not to NBU. Not just NBU, no backup software will work in that manner.

Regards....

[felonious_caper]

Thank you very much for the prompt response.

[J_H_Is_gone]

NB does not care where your tape is - and if NB was a person it would hope you have that full backup at a safe place offsite (along with its catalog).

NB knows what it did and what it has.  So it knows - Hey I did a full backup to tape 123 - so in tonight's cumulative I will only backup the changes based on time stamp or archive bit to tape 456.

Now if you did a complete restore - NB would tell you it needs tapes 123 and 456 - no matter where they are physically located.

But if tape 123 expires (by expiration date or by human intervention) and the next backup is a cumulative - it would get worried because it either has no full backup - or the only full it knows about is from 4 weeks ago - it would have to do a little bit more work to make sure it gets everything needed.