Issue :-

Very strange issue after two month of upgrading Netbackup appliance 2.7 (7.7) to 3.0 (8.0), the backups are taking more space on puredisk appliance and it is increasing very drastically and right now only 2 TB space is remaining.

Cause :-

upgrade was very smooth and things was working fine since last 2 month. But there is post upgrade snapshot which is taking space on appliance storage and that is because of upgrade only .

by default Netbackup delete the post upgrade checkpoint during post upgrade processes

if you are facing same issue , I would recommended to first contact the VERITAS support