Question : Problem: Backup Exec 12 - Differential backup media sets

Hello experts,
I have setup a backup system but don't think it is working properly.  The idea is to use a big quantum 160GB tape for a fuill backup on a Friday and then DDS4 tapes throughout the week as differential backups of the full backup on the Friday.  I ran the full backup according to plan but the differential failed because it exceeded the total size of teh tape (approx 20GB).  I have worked out that the system only updates a max of 5-6GB per day so wanted to know why this was happening?  Does all the media have to be in the same pool?  Currently I have the quantum tapes in the scratch media pool (seems to be the most reliable) and the smaller DDS4 tapes are in a seperate pool called "Differential Mon-Thur"

I really thought I was getting somewhere here but obviously not!!

Thanks

Ciscan

Answer : Problem: Backup Exec 12 - Differential backup media sets

As you correctly said the complexity in restoring an incremental is the fact that all incremental media since last full backup would be required.
But if you have small backup window or limited media space (as in your case) - incrmental may be the only option.

with differential you need only last full and most recent differential.
if you do have sufficient DDS4 tapes to hold the largest differential, then go ahead with that.

I would avoid 'modified time' as it may lead to inconsistencies and is resource consuming. using archive bit on a windows system is much more faster and reliable. modified time is good for operating systems without archive bit - e.g. linux

to suggest a proper scheme... could you let me know the exact number of tapes you have with capacity