It all depends on how much "alot" is, and how long you intend to keep this video stored for. If you're recording, lets say, 2 hours a day and you keep a months worth of video stored, on average 2 hours takes up about 1.5-2gb, depending on the format and compression rates. 2 hours could potentially take up twice that amount or more. But lets stick with 1hr=1gb. At this rate, you would be able to manage quite well with 6tb. 2x7=14gb x4 =56gb. Easily enough. However, something tells me you might be recording more. The best way to know is to do it, in all honesty. Decide for how long you want to keep a record for. Consider cloud storage as an option. Spend a week recording at the rate you plan on doing it at. After one week note the total GB size of all videos. Multiply by how long you plan on keeping them for. That will give you a rough answer.
If you plan on keeping two years or more worth of storage.... At the rates I have calculated, you will have 1.344 TB built up. That's two hours a day. Every day. At 1gb per hour. (I come up with this number considering videos compressed into .MP4 format by looking at movies in 1080p. Guardians of the Galaxy has a total runtime of 120 minutes, convenient in this case. It's total size after all is said and done is 1.85 GB. It is in .MP4 format, at least the digital copy that I own.)