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The people behind SFS
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There are some very good reasons to write a new filesystem for the Amiga. Most of
them are related to problems with the currently available filesystems but there is also
much room for improvement.
The FastFileSystem (FFS)
This filesystem is used on almost all Amiga computers as it is built-in the AmigaOS.
It is a filesystem which has some very good things going for it. FFS stores a
lot of redundant information in such a way that even if a FFS disk is heavily damaged
(partially formatted for example) that it is still possible to recover data from it with
good results using a good recovery tool.
The problems of FFS
- The 30 character limit on file and directory names.
- If during write actions to the disk a crash or reset occurs your disk will need to be
revalidated which can be a lengthy process. There is also the remote chance that
your disk will not validate at all because of somekind of error. In that case you'll
be forced to use a recovery tool to get your disk in working order again.
- Performance with large files, for example 5 MB or more, isn't very good when you use the
default blocksize of 512 bytes with FFS. Larger blocksizes can fix this problem but
introduce other problems.
- Directory reading speed without the DirCache option is quite slow, and becomes even
slower with larger blocksizes.
- The DirCache option improves directory reading speed drastically. However, using
the DirCache option will cause an overall drop of performance. Creating, deleting
and renaming files will become slower.
- Larger blocksizes can be used to improve a lot of performance problems in FFS, even to
the point that the performance becomes quite acceptable (especially with the DirCache
option). Larger blocksizes however make FFS use a lot more diskspace than it does
normally (especially if you have lots of small files).
- The caching used in FFS is very simple and you'll need a lot of buffers to get good
performance with large directories.
- There are a lot of recovery tools for FFS available. Most of them however only
work with blocksizes of 512 bytes and do not support any of the 64-bit standards which
allow for harddrives larger than 4 GB. In other words, if you have a large harddrive
or use large blocksizes you may be out of luck the next time your system recovers from a
crash.
- It doesn't seem likely there will be an update for FFS any time soon addressing these
problems, as most of them will require major changes to the internals of FFS.
AmiFileSafe (AFS)
This is another filesystem which is still in use today. It was originally named
Professional FileSystem (PFS) and was written by Michiel Pelt. I don't know the
exact details but at some point in time Fourth Level Developments has acquired this
filesystem and became its distributor. Fourth Level Developments however didn't last
very long and it seemed for a while that the development of AFS ended there.
Recently however, the original author of AFS, Michiel Pelt, has reacquired the rights
to AFS and has made it available again under a new name: Professional Filesystem 2.
This new version of this filesystem also seems to have solved most of its problems.
There seem to be recovery tools available and it's back under development again.
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