Thanks for your feedback. The reason I don't like open-source licenses is that I don't want for-profit companies to use my software without paying. The ideal license would be the one that requires them to pay while being appealing to personal users like you. I don't think these two goals are irreconcilable, but unfortunately such a license doesn't exist yet.
Free or not free aside, my question is, does it matter to personal users between this free-for-personal-use license and any of those more permissive licenses like MIT, BSD, or GPL?
I noticed that, but didn't know if Borg has another meaning. I can understand why they forked the project, but in my opinion a name that makes the origin more obvious would have been better.
Author here. The experiments actually ran BorgBackup 1.1.0b6 as you can see from the Setup section. We liked to call it Attic out of the respect to the original Attic author.
We use a pack-and-split approach -- files are packed first (as if it is building a big tar file first, although this is only conceptual) and then split into chunks using a variable-sized chunking algorithm. You can customize the chunk size but by default the average chunk size is 4MB so you won't be uploading too much small files.
I agree the name is confusing, however this is not intentional. As I explained in the other comment, I chose duplicacy because the domain name was available and this is a very good name for a backup tool (even better than duplicity).
I chose this fair source license because this is basically the only free-for-personal-use license. Many people here ask why I didn't go with a free license like GPL. Here is why. I believe software should be free for personal users, but I don't like for-profit companies using it for free. This software can potentially help companies solve a painful everyday problem (and therefore make more money) and yet there isn't a license to require them to pay if they don't distribute the software. In my opinion, this is extremely unfair to independent developers like me.
Naming chunks by their hashes is not a new idea, but this technique along does not give you a practical backup tool. The deletion of unreferenced chunks becomes a hard problem, and the center piece of lock-free deduplication is the two-step fossil collection algorithm that solves this hard problem.
I might be wrong but I want to hear more from you if you're a Borg developer. My understanding is that you may be able to have multiple clients uploading chunks at the same time, but you won't be able to exploit cross-client deduplication if different clients have a similar set of files (OS files or a large code base for instance). Moreover, if your implementation require locks then it would be very hard to extend to cloud services.
I think Amazon only blocked rclone's application key for Amazon Drive. There is no way for Amazon to prevent a third-party application from accessing S3, since users provide their own S3 credentials and Amazon doesn't know who is on the other side.
I didn't want to sound like duplicity intentionally, but duplicacy.com was still available at that time and I thought it was a perfect name for a backup tool...
Duplicacy doesn't use the filesystem events APIs. Instead, it checks the timestamps and sizes to identify modified files and only back up these files by defaults.
The main use case supported by Duplicacy but not any others including Duplicati and Arq is backing up multiple clients to the same storage while still taking advantage of cross-client deduplication. This is because Duplicacy saves each chunk as an individual file using its hash as the file name (as opposed to using a chunk database to maintain the mapping between chunks and actual files), so no locking is required with multiple clients. Another implication is that the lock-free implementation is actually simpler without the chunk database and thus less error-prone.
one of our users wrote a long post (https://duplicacy.com/issue?id=5651874166341632) comparing Duplicacy with other tools including Arq, based on his experience. I also added a comment to that thread comparing Duplicacy with Arq based on my read of their documentation.
Developer here. Duplicacy is built on the concept of Lock-Free Deduplication (https://github.com/gilbertchen/duplicacy/blob/master/DESIGN....), which allows it to backup multiple computers to the same storage without using any locks. Currently it supports local or networked drives, SFTP servers, Amazon S3, Backblaze B2, Microsoft Azure, Google Cloud Storage, Google Drive, OneDrive, Dropbox, and Hubic.
I recently released the source code under the Fair Source 5 License (https://fair.io/) which means it is free for individuals or businesses with less than 5 users. Otherwise the license costs only $20 per user/year.
By "full snapshot" I meant an incremental backup that still appears to be a full one. A full backup in duplicity is not an incremental backup so it is not qualified as a full "snapshot".