Well, it all depends on how much you're willing to spend, and how much of that 73Gb you class as "essential" data.
 
Rgds
AndyF

Sorry, I suppose I should have been more specific. My main question is whether to get a 40/80 or an 80/160, and what exactly these designations mean. Thanks.
 
 

The designation 40/80 is the size that the tape will backup normally/(or)compressed. Depending on the software and the OS when data is read off the hard drive and stored on the tape, you can do a one to one backup or a compressed backup. Depending on the files the compression will be greater, for example, with databases and some .exe's and will be almost negligible with .jpegs and most graphic files since they are already pretty well compressed.
 
Go for the larger tapes. In the old days when you had to format those things, you could spend a day doing nothing but that. Backing up to tape is a physical process and so despite advances, these will still take time. Despite the fact that you can do full backups at night, somebody has to swap out tapes. While they can be set to make only the most recent changes, you will soon learn to basically dedicate certain tapes for certain drives or folders. Despite the fact that it almost doubles the time always allow verification.
 
I have just one question, why did you make your drive Raid1? While it takes three drives, Raid5 might be the better way to go if your data is that important that you want to store it on tape.

It really depends on what your pocketbook can tollerate. DLT prices are falling because it is an older, but very viable technology. A DLT8000 drive is about $1300 street and the DLTIV tapes are about $30/ea.

I use 100/200GB LTO media here at work, and at the time when it was purchased (1.5 years ago, +/-) it seemed that would be sufficient for several years. However, they are already being used at max capacity, and I am having to resort to other options (SAN, etc.). The point being, never assume that just because the backup media is about the size you need now, that it will suit your needs in the future. Databases grow and grow, and so do all the related mission-critical files and documents.
 
Backup hardware can be expensive, but invest wisely, and you will not need to replace it for several years.
 
PS: I just read an announcement yesterday (I forget the details to be honest) that a company in Japan is coming to market with a 500GB LTO tape. Could be good news if the price is right when it comes stateside. It may have been either Sony or Fujitsu, really don't recall, sorry.