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 ?