I've been using an external harddrive to store backups of my laptop for a while now. At first I manually created a set of compressed tar archives about once a month. That was a bad system though because it used a lot of space and was a mission to retrieve files from backups. I then started using pdumpfs, which can do incremental backups by hard linking files which haven't changed. The problem I found with it however was that if a file's ownership or timestamps changed it wouldn't be hard linked even if the content hadn't changed.

I therefore set out to find a better backup solution. My requirements were as follows.

1. Incremental backups
2. Easy to access specific files from backups
3. Able to delete certain backups, preferably arbitrarily¹
4. Compression
5. Encryption

I finally settled on storeBackup which supports everything except number 5. It works similarly to pdumpfs, except it stores ownership and timestamp data separately and therefore can still hard link identical files even if these change. It compresses on a per file basis, which makes it easy to access specific files (as opposed to having to find them in an archive). Old backups can be deleted arbitrarily since they are only related by hard links. I then added encryption by backing up to an encfs encrypted directory.