#Disk layout
7 messages in this thread
This weekend, I got the dread "Corrupt Disk" requester as I tried to take a
directory on a hard disk partition. I used Sectorama, and found three bad
pointers, which I zeroed out. One pointer was in the root directory, the
other two were in a directory that hadn't been accessed in several days. In
each case, the pointer was to a "Data/Corrupt" type sector; however, it was
a copy of what should have been good data. I could jump to the parent of
the corrupt sector, and find the proper header to the (text) file, which I
could then trace through, data-sector by data-sector, without encountering
the bad sector.
So, I can now use the partition. My questions are: Were these bad pointers
likely corrupt versions of good pointers that had been there previously? I
can't tell if any files are missing, but it doesn't seem like it. Why did
only those pointers, and not the rest of the data in the sector (or for
that matter, the track or entire partition) go bad? Why were there bad
pointers in the header sector to a directory that had been OK after the
last write to it? Or are these just mysteries that mankind was not meant
to comprehend? On a related theme, how can you tell which sector is the
root directory? Is it the first sector of the middle track (on which
head?)? And, how is free space monitored and allocated? What is the format
of the sectors with the free map? Where is this info published, if
anywhere? Thanks in advance /Mike
Mike, As to how your directory/file structure became corrupt, well, only
the GURU knows. The ROOT block appears in the center of the blocks
allocated for the disk/partition. I think that all current HD's conform to
the directory/file block structure as described in the AmigaDOS Tech. Ref.
Manual. ( The info is in Bantams AmigaDOS book to ) This format may change
in the future. If you have any questions, (I'm sure you will) after
reading up on it. Just ask. <Glenn
More news as it happens: This evening, I had to reformat the partition.
One of the freemap pointers was also pointing to bad bad data. Fortunately,
nothing major was lost. Could the bad freespace pointer (the pointer in the
root directory pointing to the freemaps, that is) have caused the other bad
sector pointers? What an annoyance. Mr Blish (if you're reading this)…
what all is involved in getting new software for my old C.Ltd. ? Do I
require the PAL change? Or is the grounding wire sufficient? (That's what
I've got in place right now). Is this even helpful? /Mike
If you want to upgrade, you will have to get the PAL and install it. Involvment
consists of calling C LTD, telling them you want the upgrade, and sending them
(I think) 20 bucks. Grounding wire? Huh? The upgrade not only provides a
substantial performance increase, but will eliminate a very real hardware
problem in the interface. This particular problem could be causing you
troubles, or then again, it might not. Best to fix it, though. –Ben–
I am aware of the real hardware problem, if that is the one that tended to show
up with multiple devices off the bus. I read somewhere that the PAL
replacement was one fix, while adding a connection internally between two
points was another fix. When I installed my Insider, the docs suggested that
as long as I had the cover off, I might as well add the connection; even if my
system didn't suffer the marginal problem, the extra ground wouldn't hurt. The
connection was from F02, pin 7, to the left side of resistor C31 (near DPALEN).
Michigan Software did not say that this fix was as good as a PAL replacement,
but I did read something like that elsewhere. So, if it is just as good, I've
got it done, and shouldn't have to replace the PAL; if it's just auxiliary, I
will have to replace the PAL. Anyone else remember anything like this?
/Mike
Mike,
Yes, it is remembered by all who have been around Amigas for any length of
time. Basically, the PALs in the Amiga were getting a lot of uncalled for blame
for what was essentially a problem of trying to do multiple expansions without
regard to the specs of the expansion bus. The grounding of the PALs on the
daughterboard is something that should be done regardless of whether you are
having problems or not, though Amigas will run fine without it in most cases.
I think though, that Ben is referring to a PAL (the only one) on the C Ltd.
controller.
Regards, Larry.
In addition to what Larry said, the symptom of the missing ground strap is
crashes all the way back to KS. At least according to Ralph.
Rick