DISKS


   Ed: There's a lot of good tips here for keeping your disks and data safe,
  and it's essential reading for beginners, as is Paul's "Data_Recovery" in
  this drawer.


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	HOW TO COPE:

   It's actually quite easy to get along with your disks, as long as they're
  organised, and don't have any viruses, read/write errors or gremlins on
  your system, isn't it?  Well, yes it is; but what happens when one of the
  above does happen, that is, what happens if...

		Your system becomes unorganised.
		One of your disks suddenly has a read/write error.
		Something that previously worked 100% ceases to.

   Well, for the average user, it's time to panic, worry a lot, send the
  software back to the producer, or finally just give up. There's no need for
  any of this immature behaviour, really, it all comes down to understanding
  how some of the disk operations of the Amiga work. The Amiga itself is not
  controlled by a fluctuating bio-being, it's a machine, and it will act as
  always unless some of the situations change, and that is all that has
  happened. No prizes for quessing what I'm going on to now. That's right,
  I'll hopefully help you to understand your system more by giving you a step
  by step introduction to some of the stranger, and more overlooked features
  of the disk drive, at least to the point where you don't break down and cry
  in the event of a read/write error.


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Point 1:		Taking care of your disks

   This is rather important. Often the prevention is easier than the cure.
  Besides, it always takes up less time, and is better. So let's start at
  the basics...

		          WHAT CAN KILL A DISK:

   A disk is a magnetic medium, that is, all the information on a disk is
  stored much like a tape, magnetically. And therefore, one would assume
  subjecting a disk to a strong magnetic field (or even a weak one if you're
  accident prone) would hurt it. Well, in fact it hurts it very greatly, as
  the magnetic field from something, err... magnetic would scramble the
  individual charges on the disk, and all hell would break loose. Unless the
  disk contained something original (ie Something you could never get back)
  it would probably be best to reformat the disk, and start over. So this is
  obviously a very great danger. Commom places for magnets would be
  telephones, TVs (although unless they sat on the screen or inside them for
  some time the disks would be at now risk), and just about anywhere with
  electricity, an electrical/magnetic field could occur. This is no reason
  to be paranoid, as this is not the most common occurrence of disk errors,
  and this will probably not happen at all, unless you are either extremely
  careless, or you wanted to do it.

   Remember also that static electricity can do just as much harm to a disk
  as holding it to a magnet, and thus we have the invention of static free
  PLASTIC (non conductive) disk boxes.  Wonderful things really, but not
  totally essential for the 3 1/2 disks as they come with a protective cover,
  but they came in for the 5 1/4 disks to protect them from dust as well
  (esp. without a cover). But still essential things for keeping your disks
  organised, which we'll come to later.

   You should not open a disks protective cover at all. Period. There is
  absolutely no reason that you use to explain this. Even if diskdoctor
  (another program I'll come to) says there's a hard error on the disk, which
  according to the manual is a physical problem with the disk, there is no
  chance whatsoever of being able to see it, or correct it by opening the
  little disk cover. Believe me, you'll only make things worse for yourself
  and your Amiga. The covers are designed to make the disk as tough as
  possible, and avoid the problems of the 5 1/4 of dust and so on. Just as a
  precaution, if you ever open a disk (for whatever reason although no
  reasonable ones come to mind) don't expect to be able to put it back
  together. For the curious, I have opened a few disks in the past, and out
  of about six of them did I get any back in reasonable functioning order?
  For starters, the disk is not designed to be opened, and opening it
  permanently weakens the disk cover sliding rim (making it possible to put
  the cover back on.) Also the spring that lets the cover slide back into
  place (although I've just told you not to do this I'm sure you've done it
  in the past) is actually very small, and extremely difficult to put back
  into place (this was my down fall, out of six different attempts on six of
  my broken disks, I got a grand total of one spring in place, and even
  knowing how to do it does not help greatly). Anyhow, the inside of the
  disk is very simple. It consists of the disk itself, attached to the
  little metal ring.  A thin layer of a paper towel type of material, to
  allow the disk to spin smoothly, the spring (you won't find out where
  it goes, even if you haven't lost it already) the two plastic casings of
  the disk (front and back), and the shutter. The disk is more interesting
  together than any of its parts.

   As for the disk drive, it's more fragile than the disk, so insertly the
  disks slowly, and carefully with a bit of respect. I should know after
  I've spent over $300 repairing my internal drive just over the last 6
  months!

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Point 2:	Dealing with corrupted or errored disks

   Ever had the message "Volume xxx is corrupt, Use diskdoctor to correct" or
  "Volume xxx has a read/write error"? Have you ever run the disk through
  disk doctor and the good doc has deleted half your files?

   Well, the error messages were probably your fault, but the deletion of
  files was not. You really wanted a miracle rather than a doctor, right ?
  Okay, so at some time in our computer's life, we will end up with an error
  message, and this could occur for various reasons. For example, never,
  that is NEVER, take the disk out of the drive while the drive light is on.
  It is a really bad idea. Well actually, not always a bad idea, in fact, it
  sometimes seems like a good idea, although it should always be considered
  drastic. I'll state what the manual says: "If you take a disk out of a
  drive while the drive light is on, you risk corruption of your disk". What
  my manual would say is: "Taking a disk out of the drive while the disk
  drive is writing is invariably fatal to the disk, but taking the disk out
  while reading is merely very bad for the disk. In either case it's not good
  for the drive."  Does that clear things up a little ? When the disk is
  writing, and you take a disk out of the drive, it will immediatly cease
  writing to the disk, leaving the write unfinished, and the checksum
  unchanged. This sums up to a read/write error at least, or worse still a
  corrupted disk message. The same goes for resetting the computer. This is
  basically the same as taking the disk out of the drive, except it is worse,
  as the system cannot give you a second chance (notice the 'You MUST insert
  volume xxx in drive dfn:' signal, telling you to put the disk back in, so
  it can finish the operation, thus saving the disk from its fate.)

   So when this does, do you panic, and follow the system instructions: take
  the disk to the doctor for deletion? NO. DiskDoctor should be used as a
  last resort, and never as a first time through.

   Here are the steps you should go through.

   1. Make a backup of the disk, using a disk copier, such as PCopy (Fish
  #383), XCopy, WayneCopy, or just about anything other than that awful
  diskcopy program.

   2. If the disk just got the error itself, without any encouragment, such
  as taking the disk out of the drive too early, go to step 4.

   3. Load up FixDisk, a public domain program simply brilliant for this
  sort of work.  Make a good attempt at recovering any sectors that are
  damaged. Check all the files.  And try again. If it doesn't work this
  time, try disksalv, if you have two drives, and then, as a last resort, go
  to diskdoctor. After all that, if the disk still doesn't work, there's not
  much more you can do.  If you're really desperate, and I mean REALLY, you
  could go to a disk editor, and search for your work there, but I wouldn't
  suggest this unless you just typed in the cure for Aids, and now have
  forgotten it or something else that drastic.  This is a lot of work we're
  talking about here.

   4.  Load up DiskSpin (MD 15), and set it on the ORIGINAL disk, not the
  backup, and leave it for about half and hour.  If you notice some
  improvement, keep trying, at half hour intervals, but when you cease to get
  improvement, got to step 3, unless of course the disk is healed completely
  with no errors already.

   After that, theres just one specialised case that I'd like to bring up.
  Lots of people often get messages such as 'Key 880' checksum error.  They
  write into magazines and get replies like:

    'Ummm, theres a checksum error on your root block'

   I'd like to point out that this Key 880 checksum error can mean a variety
  of things.  A checksum error means that some of your data has gone haywire,
  and is not correct, because the AmigaDOS normally keeps a sum of all data
  on a certain section of every piece of data.  The key 880 part means that
  its on block 880, or the root block.  So, what does it mean?

   Well, to give you an example, if a Virus were to get to your Xennon II
  disk, then the next time you booted it, a workbench screen would come up,
  displaying the Key 880 checksum error.  This is because games such as these
  do not support AmigaDOS error checking, and don't have a checksum on the
  disk.  It's a non DOS disk, that's been installed.  Unless you keep a
  backup of all your bootblocks, there's not much you can do about this.  If
  the affected disk was not a non-dos disk, then you should just load up
  Fixdisk, and see what it can do.  Oh, never use diskdoctor on a non-DOS
  disk with the key 880 problem.  It only makes it worse.

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Point 4:		Organising your system

  A good system should include:

   An original Worbench & Extras Disk (Totally untouched. Never write
  enabled in its life, for no matter how short the time)

   A customised backup of the Workbench & Extras Disk. (With a few small
  changes, such as Preferences colour settings, pointers, printers and so
  on.)

    A highly customised workbench disk. (Optional, I use one. It should
  contain commonly used utilities, virus killers, and ARP is always nice.
  This if you have one, should be your most booted system disk. The one you
  use for just about everything. If you don't have one, you should use the
  customised backups.  A good example is Super Workbench from Prime Artifax,
  or there are a number of good ones in the MegaDisc PD library.)

   Your PD software (if any).

   Your Commercial software Backups of the commercial software (where legally
  viable)

    Your data disks.

   A system saver disk. (This should be a disk which you will never write
  enable, after the original writing. It should be written to when you are
  101% sure you don't have a virus. It should be packed with every virus
  killer you could find, and should be an installed dos disk (bootable).
  This is so when you have a virus, like the Lamer II, where it hides itself,
  you can cold boot to this disk, being absolutly sure you have no virus in
  memory when you run the virus killers, contained on it.)

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   Well that's about it. I hope you found that useful. Remember that if
  something is continually going wrong with the system, you can format a new
  disk, and see if that works without a error. If it doesn't, it might not
  be your disks, or a virus, it might be the hardware. The Amiga is just a
  wonderful machine, not something that has moods. If it doesn't work, there
  is a reason. The trick is to find that reason, and make the reason
  redundant.


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