obroin@hslrswi.UUCP (Niall O Broin) (07/31/87)
I have recently experienced some very odd behaviour on my hard disk and I
wonder has anyone got any ideas as to what caused it. I am running MS DOS 3.2
on an Amstrad 1512 with a Shugart drive. I moved house recently so I just
last night got my machine back on the air. Before moving, I had had some disk
errors, so I was ready for problems. On booting, I got a message that there
was a disk error in FAT 1, but it still booted O.K., though I also got 'bad
or missing CONFIG.SYS' - it was junk. My previous problem had been with a
directory, C:\SC4. I could not read it and CHKDSK wanted to convert it into a
file - needless to say, I did not let it. CHKDSK also reported 417 lost
clusters in 85 chains - again, I did not let it - CHKDSK's cures are often
worse then the disease (Headache ? - a quick lobotomy will cure that !).
Despite answering N, CHKDSK reported 894,nnn bytes were freed and DIR showed
that much more free space - I have had this kind of behaviour from DOS before,
where it badly loses track of its free space - a reboot is usually needed to
cure it, to make it re-read the disk.
I then ran Norton's DT (on files) which reported problems with two files - no
big deal, as they were programs of which I had copies. However, when it got
to C:\SC4, DT could not CHDIR, apparently, and I got DOS Abort, Retry, Ignore
message - after two Ignores, DT went on to the next directory.
Now comes the odd part. At this stage, I was despairing of recovering data
from C:\SC4, though there was not too much to lose. I decided to RMDIR it
and then restore it with UNREMDIR. So first DEL C:\SC4, yes, I am sure,
and then for some reason, I did DIR C:\SC4. Voila ! Empty directory
appears. (recall that I could NOT read this directory). Shelve plans for
RD C:\SC4, and substitute QU - result - '48 erased files in this directory,
all may be Quick Unerased'. Recover all files and DOS can read them all.
One file is corrupted - an ARC which PKARC says is 'NOT AN ARCHIVE' and ARC
says has an error in the first header. DOS can now CD happily to and from
C:\SC4 with no problems. I then ran DT again and it found NO ERRORS with
files. Odds teeth ! What is happening here ? I am not unfamiliar with
DOS or recovering dodgy disks, but this puzzles me. All I can think of is
that the corrupted ARC was the cause of all the nastiness, including the
FAT error on boot, and that Norton's QU fixed the errors in FAT 1 by
reference to FAT 2 while unerasing the files - an undocumented feature
(Don't quote me - I'm not a great manual reader except of course when all
else fails, though I have been known to tell others to R.T.F.M. on more
than one occasion). But that this also fixed the two files that DT found
broken the first time ?
A nasty thought has just occured to me - perhaps other files are actually
corrupted too, though appearing O.K. to DOS ! I don't think so however -
one of the files DT reported as bad the first time was MASM.EXE, and after
all the shenanigans above, MASM was reported O.K. and I assembled CPUID.ASM
as a quick test with no problems.
SO . . . fortunately, I don't need any help on this one. I intend to
backup the disk tonight and then run HDTEST on it to see if it is in
fact in any way physically flaky. But I remain damn puzzled by the above
behaviour - (Why couldn't that have happened with a paying client - "I've
fixed your sick disk and got your invaluable data back - that'll be X
please" where X is an arbitrarily large figure - ah well !) Has anyone ever
experienced anything remotely similar ?
Niall O Broin
AXE Software Development
Hasler AG
Berne
Switzerland
obroin@hslrswi.UUCP
There are a lot of things money can't buy, but have you ever tried getting
them without money ?