Practical File System Design with the Be File System (1999) [pdf]

That's a great book. Far from state of the art these days, but still very inspiring for beginners.

I took a lot ideas from it, while designing some in-house DB solution 10 years ago.

I wanted to take a break (A month or so) from my current project to learn a bit about file systems. I've played with Xv6s filesystem before and am interested in reading about bfs, fossil and related arch and modern ideas in general. Any resources would be really appreciated.

A classic on the UNIX filesystem would be Chapter 4, INTERNAL REPRESENTATION OF FILES, from: Maurice Bach, Design of the UNIX operating system, 1986. It's quite short, about 25 pages.

I believe there is an online version available.

This is a classic, although over my head in a lot of ways. I've had it on my bookshelf for years. BeFS with it's awesome metadata capabilities is what spotlight should have been.

+1 for Haiku. I am not a regular user but I listen to the developer list traffic and admiring hopefully; they are often fighting off the "one troll" that antagonizes the list, or of course bikeshedding about when and whether to have the next release, or if they should try and promote the nightlies more instead, since there hasn't been a release since Alpha4 (2012) and substantial progress has been made since then.

For anyone who is not in the know about the BeOS revival OS and its current events, I assure you that Haiku is not dead ;)

The recent addition of package management with recipes and a ports tree breathes new life to the single-user desktop OS. Two factors that get repeated by the list-complainers: 1) people that hardcoded some path in their software product back in BeOS R4/R5 days that needs to change now because package management (this one either comes from the developers of said product, or the users, and you can never tell which unless they follow up with a ticket or a fix)

2) Hardware support is very good, until you get to modern wireless chipsets, 64-bit computers, or USB3. A lot of this comes from drivers ported over from FreeBSD, which will lag behind by a version or two. So there is a potential that it will get better, but still unlikely you are going to be able to run Haiku on bare metal of your brand new brand name laptop from the store with Blah-Next-EFI-SecureBoot Thing and Windows 10 (or realistically, new computer you bought in a store even today.) The progress is going to lag behind a bit because there's obviously non-zero effort required in porting new releases of any kind of upstream components.

Wooo OT -- but how often does an even tangentially related to Haiku post get to the front page? I regret nothing.