Comment by ryao

I first tried btrfs 15 years ago with Linux 2.6.33-rc4 if I recall. It developed an unlinkable file within 3 days, so I stopped using it. Later, I found ZFS. It had a few less significant problems, but I was a CS student at the time and I thought I could fix them since they seemed minor in comparison to the issue I had with btrfs, so over the next 18 months, I solved all of the problems that it had that bothered me and sent the patches to be included in the then ZFSOnLinux repository. My effort helped make it production ready on Linux. I have used ZFS ever since and it has worked well for me.

If btrfs had been in better shape, I would have been a btrfs contributor. Unfortunately for btrfs, it not only was in bad shape back then, but other btrfs issues continued to bite me every time I tried it over the years for anything serious (e.g. frequent ENOSPC errors when there is still space). ZFS on the other hand just works. Myself and many others did a great deal of work to ensure it works well.

The main reason for the difference is that ZFS had a very solid foundation, which was achieved by having some fantastic regression testing facilities. It has a userland version that randomly exercises the code to find bugs before they occur in production and a test suite that is run on every proposed change to help shake out bugs.

ZFS also has more people reviewing proposed changes than other filesystems. The Btrfs developers will often state that there is a significant man power difference between the two file systems. I vaguely recall them claiming the difference was a factor of 6.

Anyway, few people who use ZFS regret it, so I think you will find you like it too.