[Coco] Can an OS-9 disk get fragmented?

[Allen Huffman]

The OS-9 file system, RBF, can get fragmented as easily as anything 
else out there.  It's probably a more complex file system than DOS, so 
maybe it has the potential of even more fragmentation.

There were a number of utilities to defrag a CoCo OS-9 drive.  First, 
some terminology:

Defragment - make all files into one chunk.  You can degragment all the 
files, but the free space can be horribly fragmented, causing 
fragmentation to start happening immediately.

Optimize - grouping files and directory sectors together in such as way 
that the drive has to do fewer and smaller seeks to get all the parts 
of a file/directory.

Now, the utilities that were made for the CoCo include:

Burke & Burke's FSR (file system repack) -- this was the BEST 
optimizer/defragger.  On my old 20MB drive, after a complete defrag 
(which could take 20+ hours!) the drive was SILENT -- until 
fragmentation set back in.  It would put the FILE ID sector and then 
the file segment list and then the sectors of the file or directory all 
back to back -- VERY SWEET.  This one was the best, but massively time 
consuming.

Burke & Burkes compactor -- I forget the full name, but it ran on a 
graphics screen and was MUCH faster, but didn't optimize.  It reduced 
fragmentation and packed things together so all the free space was at 
the end of the disk.  Nice.

JWT's Optimize Utility Set - Jordan Tsvetkoff had an EXCELLENT set of 
disk utilities for OS-9 (must have, must have, right up there with dEd, 
the B&B utils, etc.).  "optimize" would RAPIDLY run through all the 
files on the disk and degrag the files (not touching the free space).  
This was awesome... But... did you know:

OS-9 defrags by itself.  If you open a file, and specify that you want 
200K, it will find a 200K contiguous block of sectors for you.  So, if 
you want to defrag, you do this:

open file A
get file A size

create file B with size set to size of A
read from A
write to B
close A
close B
delete A

...that little trick (which is why DSAVE defrags) is what optimize did 
-- real slick.

There may have been other utils but I never heard of them.

There were utils to repair the bitmap/DAM (disk allocation map), set 
bits (sectors in use), clear bits, etc.  Armed with these tools, and 
dEd, I could just about repair anything -- got real good since my HD 
crashed all the time...

I wiped out the CompactFlash card I had a few months ago -- found a 
tech manual for OSK on the net (same format, basically), and used dEd 
to bring it back.  I really like the RBF file system.

		-- Allen