Just my tuppence worth here: I started using tarsnap a couple of weeks ago and it's been superb. I needed a way to create encrypted, offsite, incremental backups and I'm not aware of a service similar to Colin's -- usually you get to choose two of those options, not all three. Also, customer service has been excellent after I expressed an interest in using tarsnap under Cygwin: Colin has responded in a timely and professional manner to my emails, so now I can also back up my Windows server as well.
It's sometimes unclear what a startup plans to offer to its customers, and how it plans to make money. In fact, sometimes it's utterly baffling. tarsnap is a necessary product with affordable pricing, and I wish Colin every success with it.
You really hit the nail on the head. There's a solid business plan coupled with the three things backup needs. One thing to add: Tarsnap is even better than incrementals. It's snapshots that don't take up more space. That means that you can do things like delete an old archive since the newer ones don't rely on it for restore. Each archive works like a full backup even though it doesn't take up the storage space of a full backup!
I'm surprised that VC hasn't been banging down Colin's door. He has a workable business plan and a product that's wonderful. Tarsnap, in my opinion, should also have broad appeal to businesses. I know my company does a disk->tape thing, but often the tapes aren't so reliable, the whole setup is labor intensive, and it's stored in one location. Businesses are less hesitant to pay than consumers are and Tarsnap offers a lot of value.
Indeed it is better than incrementals, being close to the behaviour of rsync which can also symlink to previous backups. Surprisingly, tarsnap is much easier to use than rsync: my perl script to work out what rsync should be doing is about 30 lines long, whereas the one to kick off tarsnap is about 3 lines.
As for VC, I can see why sometimes that's not always the best option, especially if the founder has to give up control in return for funds. However, I think it would be great to see more projects like this on HN, grounded in technical expertise and solid business needs.
I'm surprised that VC hasn't been banging down Colin's door.
Probably they either aren't aware of tarsnap or they aren't sufficiently technically inclined to be able to try using tarsnap for themselves. :-)
That said, I have had some inquiries; but my response so far has always been that at the moment, for the small amount of money which I could usefully apply, funding would be more of a distraction than it would be worth.
Don't worry, I plan on doing all of that stuff, too. But I don't need people to beta test a website for months and months -- so making a nice-looking website isn't a high priority while tarsnap is still in beta testing.
It's sometimes unclear what a startup plans to offer to its customers, and how it plans to make money. In fact, sometimes it's utterly baffling. tarsnap is a necessary product with affordable pricing, and I wish Colin every success with it.