I created a maintenance plan to backup all user databases (full) and set them to expire after three days.
This has proved to be cost inefficient in regards to disk space so I want to switch to differential backups.
I then created a maintenance plan to backup all user databases (differential) and set them to expire after seven days.
I had thought the first time this job ran that the first backup would have to be full but it's not, it's significantly less than what a full backup should be.
I thought it would work like this:
Day 1: Full
Day 2-7: Differential
Then on day one it would do another full backup and start all over.
Am I just misunderstanding how differential backups work?
I mean what did the plan back up differentially if it didn't do a full backup first?