In addition to his normal daily backup, my “friend” would like to do a weekly backup to a media which can be saved indefinitely and never written over. It’s about 40GB of data. What’s the most cost-effective way to do this? Tape cassettes? DVDs?
Also, my friend would like to just let the backup run overnight - he doesn’t want to have to be changing disks or cassettes or whatever.
TIA
I’m a bit confused. Does your friend want to make a one-time backup of that 40 GB of data, never to be touched again afterwards? In this case, why does it matter if the backup is done overnight or that he has to change any data medium?
Anyway, to save data “indefinitely”, you better engrave it to high-grade steel (or even more high-grade metal) plates, but in digital form it’s impossible.
I’m no expert in backup strategies, but the first you can rule out for a reliable backup are optical media like DVDs and magnetical like tapes. If this data is of such great value, I would recommend to store it on two separate hard drives and verify the data daily. If one of them should fail, you can swap it immediately for a new one and still have the data on the other. You could simplify this process by using a RAID system, but I’m no expert on this either, so let’s hope someone with more experience will participate in this thread.
You can get a 500GB external HDD from Best Buy for around $60. That’s what I would do. Back everything up, then keep it unplugged (from the wall and the computer) to protect from any kind of electrical surge. If you’re really worried about this data, get two of them, copy everything on to both of them, keep one at your house and the other one somewhere else.
Just read the OP again, and noticed that I overlooked the word “weekly” the first time. So please forget about this question.
Wow, I missed that as well. In that case, pick up a 500GB drive from Best Buy and get (for free, from Microsoft’s Website) a program called SyncToys. It will do exactly what you want to do. It will only add new data to that backup but will never remove anything from it.
Well that will last for about 10 or 15 weeks. Then what? Do I just buy a new HDD every couple months?
Well, if you got to store 40 GB of *new *data each week, either this (that’s the safer option), or else you burn it to DVDs, but as I said before, that’s not a reliable method in terms of durability.
Thank. Basically my “friend” is worried about a Stuxnet type attack where his data is corrupted in some subtle way without him knowing about it until months after it happens.
In this case, the normal dual daily backup he does to flash drives will not protect him.
So the idea is to do a weekly archive type backup on top of the daily backup.
Just wanted to add: If you go for storing your data on several hard disks, then go for the best storage/cost ratio, i. e. you should get you HDs with at least 2 TB.
Oh, I mis-understood the question. I assumed it was 40GB of data that would be more or less unchanging. Weekly backups to catch the small changes or added files, but not competently recreating the entire backup each week. Honestly, based on the way the OP was worded, I just assumed he wanted to back up his porn.
Me too. 
Assuming we aren’t worried about Physical issues (fire, etc), just data corruption, the solution requiring the least screwing with IMO is:
A blackx duet to hold 2 hard drives:
Two 2TB hard drives:
Acronis True image Home: (Set backup to FULL method, and don’t enable auto-cleanup
That should cover you for approximately two years without changing tapes or anything.