5 years of bootstrapping a nutrition & fitness tracking web/mobile app for me.
After the first few months it was only making enough income to cover basic hosting costs and not much else, so I ended up getting a job (well, co-founded a different startup with good funding). In the next two years, I was just doing the bare minimum to keep it running, and it grew 80% each year. Start of year 3, other startup failed and I had spare time to invest in the site and it was making maybe 8000/month in revenues, and the decent yearly growth has continued so that now in year 5 I can comfortably live on the business, and have a few employees / contractors to help with support and development.
But all you need to defend against bad actors is for archive.org to hang on to a SHA256 or 512 for every chunk. Much simpler than a distributed blockchain.
It’s a little more complicated than that. I could temporarily take a chunk, compute the hash, then throw it away and report back that I am happily storing the data, even though I’m not.
Anyhow, read the permacoin paper. It’s pretty cool, and it needs a large petabyte data seed to secure the network. Seems like a win-win to me.
The central server has access to the entire file, and hence can compute the hash of any arbitrary chunk. Challenges/verifications don't have to happen all that often ([1] indicates they are looking at once a month) so creating a unique challenge for each user shouldn't be too compute intensive.
For each known user:
- Central server chooses random chunk of each file it wishes to verify the user still has. This could be any length from as long as the hash function to the whole file size and could be offset any number of bits.
- Client is asked to provide the hash of the chunk using the file stored locally.
Precomputing hashes for all possible chunk permutations would take up substantially more space than simply storing the file in the first place. A bad actor would need to store the hash for all the possible chunk lengths starting from every possible start location in the file which is in the order of O(n^2) where n is the stored file size (500GB in this case). For reference that would be about one third of the entire 20PB archive for a single 500GB chunk if using a 256 bit hash function.
It's a good thing in this case they also don't have to worry too much about bad actors, since it's a fundamentally altruistic endeavor. Worst case scenarios:
1) Someone keeps downloading the full archive and throwing away;
2) Someone wants a file erased, keeping it with the intention of denying access in some future.
--
1) Bandwidth has costs on both sides; just balancing upload among receivers would probably suffice for this not to be a problem.
2) Assigning large random chunks to downloaders should prevent this "chosen-block attack"; add in some global redundancy for good measure and that's probably enough (although I still wouldn't trust this 100% as a primary storage, only as an insurance storage).
The added bonus of periodically validating random chunks is that it forms a sort of data-scrubbing function, allowing the detection of non-malicious failures due to bad sectors or whatever as well.
I have a little over 10k DAU for http://cronometer.com/ and it runs on 2 fairly small cloud instances + a cloud database. A single host can handle the load fine, but I keep 2 running to survive failures.
And it took me nearly 4 years to get that many users. We can’t all grow like facebook!
True, it started as a hobby, so it’s been fully bootstrapped and I’ve spent less than $2500 on actual marketing to date. Advertising in the Health / Diet space is super pricy, the ROI still doesn’t make sense. CPA >>>>>> LTV
No, the additional load is not worth it. It would be one of the least sustainable things you could do due to all of the heavier columns you'd have to use.
I had been waiting 4 months for my withdraw -- just email their support and ask them to cancel the transaction. They were able to do so for me today, and I can now trade them again (and transfer them out as BTC anywhere).
After the first few months it was only making enough income to cover basic hosting costs and not much else, so I ended up getting a job (well, co-founded a different startup with good funding). In the next two years, I was just doing the bare minimum to keep it running, and it grew 80% each year. Start of year 3, other startup failed and I had spare time to invest in the site and it was making maybe 8000/month in revenues, and the decent yearly growth has continued so that now in year 5 I can comfortably live on the business, and have a few employees / contractors to help with support and development.