Question

What are some best practises for prototyping a filesystem?

I’ve had an attempt in Python using fusepy, and now I’m curious:

• In the long run, should any
  respectable filesystem implementation
  be in C? Will not being in C hamper
  portability, or eventually cause
  performance issues?
• Are there other implementations like
  FUSE?
• Evidently core filesystem technology moves slowly (fat32, ext3, ntfs, everything else is small fish), what debugging techniques are employed?
• What is the general course filesystem development takes in arriving at a highly optimized, fully supported implementation in major OSs?

Answer 1

In the long run, should any
respectable filesystem implementation
be in C? Will not being in C hamper
portability, or eventually cause
performance issues?

Not necessarily, there are plenty of performing languages different to C (O’Caml, C++ are the first that come to mind.) In fact, I expect NTFS to be written in C++. Thing is you seem to come from a Linux background, and as the Linux kernel is written in C, any filesystem with hopes to be merged into the kernel has to be written in C as well.

Are there other implementations like
FUSE?

There are a couple for Windows, for example, http://code.google.com/p/winflux/ and http://dokan-dev.net/en/ in various maturity levels

Evidently core filesystem technology
moves slowly (fat32, ext3, ntfs,
everything else is small fish), what
debugging techniques are employed?

Again, that is mostly true in Windows, in Solaris you have ZFS, and in Linux ext4 and btrfs exist. Debugging techniques usually involve turning machines off in the middle of various operations and see in what state data is left, storing huge amounts of data and see performance.

What is the general course filesystem
development takes in arriving at a
highly optimized, fully supported
implementation in major OSs?

Again, this depends on which OS, but it does involve a fair amount of testing, especially
making sure that failures do not lose data.