I have read the Wikipedia pages for both these file systems:
but I couldn't find a real answer. For example, for SFS the common Operating Systems that use it are listed as AmigaOS, AROS and MorphOS. But I haven't heard of those being used today. Unix-based OSes like FreeBSD also use ext2/3 by default — or at least that is what I have read, might be wrong.
Are these file systems still used?
The reason I am asking is that, for example, the SFS uses a technique to avoid fragmentation when appending data to a file. It removes the allocated data completly (if the extend has no room when after the initial data) and places it in a new place where enough sequential data is free. The SFS is the only file system I have found that does this. Is that correct?