I have a setup for a customer whereby a full backup is conducted on a Friday – then Monday through to Thur, differentials are carried out. Now, there is a single media set for these two jobs (I understand that is obviously not the best way, if even a good way, of doing this, but, the customer uninstalled Backup Exec without recording his original setup, but wants it back exactly how he had it, I'm just confirming that a certain event won't occur) which both the Full and Differential will backup to.
Now in terms of the overwriting – the full is set to overwrite the media, since it runs once a week, I always want it to overwrite the previous weeks Full. But the Differentials are too going to the same media set. Now, obviously as they are differentials, I want them to always overwrite the previous days differential, so I have set them to Overwrite media when the job begins.
But, does this mean the Monday Differential will go ahead and start to overwrite the full backup from Friday, or will it not because the Full and Differential are two separate jobs?
Best Answer
hmallet is right...however:
Since your question seems to state that you have to use a single media set...yes, you would be overwriting the FULL with the first DIFFERENTIAL that takes place.
If there's enough room on the media, the best bet is to set the media set's Overwrite protection period to 6 days as hmallet has said, and set the Append period to 1 year (or anything longer than 6 days).
This would allow the backups to write a FULL backup and then up to 6 differentials to the same media, then it would overwrite again on the next FULL...repeat.
NOW, if there's not enough room on the media for a FULL and 6 differentials, then you need to consider doing what hmallett recommends and using multiple media and media sets. OR, you can switch to a FULL and INCREMENTAL method instead of DIFFERENTIALS....after all, you are only keeping a week's worth regardless on a media, so restoring a FULL then incrementals won't be that bad at all.