An anonymous reader writes "Almost three years ago, I started looking for a cloud storage service. Encryption and the "zero-knowledge" concept were not concerns. Frankly, after two weeks testing services, it boiled down to one service I used for almost 2 years. It was perfect — in the technical sense — because it simply works as advertised and is one of the cheapest for 500GB. But this year, I decided changing that service for another one, that would encrypt my files before leaving my machine. Some of these services call themselves 'zero-knowledge' services, because (as they claim) clear text does not leave your host: they only receive encrypted data — keys or passwords are not sent. I did all testing I could, with the free bit of their services, and then, chose one of them. After a while, when the load got higher (more files, more folders, more GB...), my horror story began. I started experiencing sync problems of all sorts. In fact, I have paid for and tested another service and both had the same issues with sync. Worse, one of them could not even handle restoring files correctly. I had to restore from my local backup more than once and I ended up losing files for real. In your experience, which service (or services) are really able to handle more than a hundred files, in sync within 5+ hosts, without messing up (deleting, renaming, duplicating) files and folders?"