Every television professional should have certain numbers memorized. Here are mine: 70, 100, 150, 600.
Here's what they mean:
70 gigabytes per hour: ProRes 422.
100 gigabytes per hour: ProRes 422 HQ.
150 gigabytes per hour: Uncompressed SD.
600 gigabytes per hour: Uncompressed HD.
Those are all 60i, so they're worst-case-scenario. Also, they're rounded up a bit for ease of memorization and also to give you a little bit of wiggle room when you have to deal with audio and junk.
By a delightful coincidence of math, you get about 100 minutes of uncompressed HD per terabyte of disk. So two terabytes will hold 400 thirty-second spots.
Now, only
you can tell
us if 400 spots is sufficient for your needs.