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32 FAT Corruption by 16 FAT Access,

Symptoms,

and

What 2 do about it.

First Wiz Tip, ALWAYS backup.

{Geek Speek for 'My Windows was giving me random Fatal Exception' and 'illegal operation' errors, it kept locking up and doing ScanDisk, occasionally booting up into 'SafeMode' AND NOW my screen says 'Invalid System Disk or Disk error. Please insert a valid System Disk and press any key'. You do - and nothing happens!}

1st possible warning sign is a C:\ partition of 1.2 GigaBytes. This was a limitation of the older DOS6.22 and the first 'Upgrade' version of Windows95 from Win3.X. You can also cause a FAT corruption by running older DOS programs from your Window's Dos window.

2nd warning sign, and prelude to total system corruption, scandisk finds lost file fragments. This is bad news :-( These could be files once lost are not needed by system. They may not even be needed by any programs. But they could be needed system files and that is when you will begin seeing random error messages occurring more often and with increasing fatality. {grins} Your system locks up and only a hard {dirty} shut down gets you out. Of course, scandisk will run again. {bigger grins}

Skip this part if the physics don't hold much interest for you. {Go directly to 'What 2 do about it'} But if ya' want to know what 16 FAT has to do with the Windows 32 FAT operating environment, venture on brave apprentice :-)

The FAT {File Allocation Table}, consists of 3 parts: BOF, data, EOF {Beginning Of File and End Of File}. A small section of track on your hard drive's disk {16 bytes} is allocated {addressed physically} by each FAT cluster. IF an older version {prior to Win95B} of Fdisk is used, it DOES partition the drive using 16 FAT. Then, when you install Window 95 or newer, it emulates a 32 FAT environment by combining two 16 FAT clusters.

This is like patching potholes. Works for a while but watch out for heavy traffic. That pothole is still there just waiting to be uncovered. Yeppers, new ones even crop up trying to miss the others. LOL Yeppers, a 16 FAT file WILL sooner or later find a neat little 16 byte cluster to jump into.

When that does occur, the EOF is now re-assigned to the 16 FAT EOF address. The new BOF is now in the middle of a 32 FAT :-( Those lost file fragments found by scandisk? Yeppers again. They are the part of the file that MUST be truncated {chopped off} when the 32 FAT oriented Scandisk resets where the EOF is supposed to be. This, as I said, is the beginning of the end. Cascade failure of other clusters will occur each time this 16 FAT file is found and used again. No, Defrag does not correct the problem. It actually could hasten the system's demise.

Eventually, one or more of your system start up files will be corrupted and it is at this point that you will wish you knew where all cards' drivers are. You will also find out if you have a good boot up floppy. It is also too late to do ought else but call your local computer guru if you do not print out these pages {3 ?}.

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What 2 do about it.

Do NOT try to reformat your Primary {C:\>} drive UNLESS you are prepared to reinstall your OS

{ Windows 9x } This means: If your setup is on a CD, does your bootup floppy install any needed CDROM support drivers? I have found the Bootup disk made by Windows 98 often {not always} has the CD Drivers :-)

IF you are absolutely certain that you will be able to access your CD Drive after you wipe your Hard Drive {means losing ALL your drivers - even your DOS drivers for CD} You say you still have the Setup Floppy for your CD? How old is it? Is it still readable with no bad spots {run a 'through' ScanDisk on it}? Again, if YOU are sure you are ready to erase and wipe out all files {Important documents and database files backed up? Email? Pictures? Address Books?}, let's get started {big grins}

1st, Print out this page. You'll need it :-) Yes, writing it down would be good practice, but be cautious of typos and syntax {spacing and slashes}. Once started down this path, you will be slowly losing a safe passage to return and say, "What was I supposed to do 1st?". Yes, it does matter what order some of these steps are done in. Different results can be expected if done out of order. Also, always reboot between each step.

Step one: Boot up using your floppy StartUp disk with the CD ROM Support. {May require changing your boot up sequence in BIOS}

A. You should be at the A:>\ Prompt. Type 'ver' without the quotes and hit enter. {no, your mouse don't work at this point - grins} The Wiz sez the OS version should be Windows 95 or newer.

B. Insert a CD ROM {preferably your Windows setup CD}. Now, type the letter of your CD drive. {D: if only one HD drive and no partitions.} Hit enter. Type 'dir' {again without the quotes} and hit enter. You should see a list of folders and then files flash by and then DOS prompt at bottom again. Do they look like the files of your Windows setup CD? Yes? Good!

C. Type A: and hit enter. Now comes the fun stuff. Type 'fdisk' hit enter. You will be wanting to delete ALL partitions. Use choice 3 to delete partitions. To see partition information, select choice 4 and hit enter. Your 'Esc' key is your Panic button {biggest grins}

D. Once you have deleted ALL partitions, you MUST reboot. Yes, reboot BEFORE recreating partition(s).

< Reboot >

Step two: Verify C: partitions are gone.

A. Still booting up with your good Win95B or newer bootup floppy with CD support, you will from the A:>\ prompt, {Do NOT panic, you may even get an ominous warning saying that your hard drive was not detected and about some virus being able to cause such an error - grins} Yeppers, your C should be in this shape at this point. There is no data and no FAT addresses yet assigned for data to be put on. Well Done! Too late now if you just remembered you were supposed to have backed up any files.

B. Type A: and hit enter. Now comes more fun stuff. Type 'fdisk' hit enter. You will be wanting to now create partitions. To see partition information, select choice 4 and hit enter. There should be NO partitions defined.{biggest grins}

C. The Wiz suggests making just one partition on drives smaller than 8 GigaBytes. Hit the 1 then hit 1 again. Fdisk will test drive size and ask U if U want to use all space it found for your new partition.. just say NO.. that is correct, say NO at this point, it will test a second time for available space. This time, U may choose to use part or all of available space as your C drive. Just hit the 'Enter' key to accept setting the entire space found as the partition. Call me superstitious, but it seems to work a bit better that way :-)

D. You will then B prompted to set the partition Active, choice 2 will set your drive active and make it ready to B formatted as a bootable drive.

< Reboot >

Step three: Verify C:>\ has been wiped clean and create new partition(s).

A. Still booting up with your good Win95B or newer bootup floppy with CD support, you will from the A:>\ prompt, type 'c:' and hit enter. You should get a C:>\ prompt.

B. Type 'dir' hit enter. Do NOT panic, you should get an error message saying invalid media or error reading disk. You may even get that ominous warning again about some virus being able to cause such an error. {smile} Nope, your C should be in this shape at this point. There is a FAT now but the FAT is not yet formatted to accept data. Well Done! It B way too late now if you just remembered you were supposed to have backed up any files.

C. Type A: and hit enter. Now comes more fun stuff.

< Reboot >

Step 4: Format your C: Hard drive

Ready to format? From the A:\> Command Prompt, type

'format C: /u /s'

{again without the quotes} This will do an Unconditional reformat of your C: Drive and install the System files to a new clean C: Drive.

You will B given a couple of chances to chicken out of formatting this drive. R U sure it is the right one? Confirm that U want it formatted J Good luck. Watch what size it says it is formatting. Does it look close {not exactly but close} to the size of your Hard drive? Hope so J

You should now have a nice clean new drive, which is bootable. Remove floppy, reboot system, and start enjoying all your new Disk space. Hope you remembered to backup in case you now find that there were some important emails or text documents on the old drive.

U can read the information at the Microsoft Knowledge DataBase

{ http://support.microsoft.com/support/kb/articles/Q255/8/67.ASP?LN=EN-US&SD=gn&FR=0 } to learn more details about how to use Fdisk and Format to partition or repartition a Hard Disk.

Wiz Tip #1 - Always Backup.

You heard about when Satan challenged Christ to a PC Contest?

The Computer Programmer's Contest {I first saw this in an email message dated Tuesday, April 28, 1998 2:32 PM}

Jesus and Satan have an argument as to who is the better programmer. This goes on for a few hours until they come to an agreement to hold a contest, with God as the judge.

They set themselves before their computers and begin. They type furiously, lines of code streaming up the screen, for several hours straight.

Seconds before the end of the competition, a bolt of lightning strikes, taking out the electricity. Moments later, the power is restored, and God announces that the contest is over. He asks Satan to show what he has come up with.

Satan is visibly upset, and cries, "I have nothing. I lost it all when the power went out."

"Very well, then," says God, "let us see if Jesus fared any better."

Jesus enters a command, and the screen comes to life in vivid display, the voices of an angelic choir pour forth from the speakers.

Satan is astonished. He stutters, "B-b-but how?! I lost everything, yet Jesus' program is intact! How did he do it?"

God chuckles, "Everybody knows... Jesus saves."

No Frames Entry Ways