recovering hard drives information

[amigaoneproductions]

You say the drive is dead,  does it spin up and make the usual noises ?  if not there is no chance of getting any data off the drive in that state.

All is not lost however,  the problem could be on the PCB that controls the drive,  if you can find an identical working drive (exactly the same make and model), you could swap over the PCB and try that.   I've used that trick before,  although it does help that I tend to work on large sites where there are 1000's of identical machines so finding an exact match is not too difficult,  your old drive might be a bit more of a challenge to find another one of the same type,  but you never know your luck ;-)

[amigaoneproductions]

Oliver wrote:
I use a dyson too.  Damn good.

Heating definitely can work, but I would try freezing first.

Agreed,  Dysons SUCK !

[amigaoneproductions]

Hyperspeed wrote:
I wonder if hard disks have their own air purification filters?

Yes they do,  well,  nothing that looks high-tech,  it's a fine paper / cloth filter,  have you ever seen on a hard drive's casing "Do not cover this hole" - That's the hard drive breather hole, under which is the air filter.
There's usually a small sachet of silica gel hidden inside as well to absorb any moisture that does get in there.

I have stripped down several hard drives,  if you are careful, you can do all of the above without a clean room.  Eating a jam sandwich or a sticky toffee pudding while working on a hard drive is not really recommended ;-) ,  but all of this can be done,  all this talk of having to send a hard drive to a high cost lab is utter nonsense.

These are the facts (As written by me,  a computer engineer who has been doing this stuff for the last 18 years :-) )

If the hard drive is spinning and being recognised by the OS,  then software recovery tools will usually get the job done.

If the drive is not spinning or seen at all, i.e. not even at the lowest level then you have a more serious fault which will probably mean getting out your screwdrivers.

If the PCB is the cause of the fault,  which is the most likely - it's the most complicated part of the system,  changing it with an IDENTICAL (same revision, same firmware) one will solve your problem.

If you still need to go further,  then changing the head assembly (if the drive is spinning, this is the easiest bit to do)  or moving the platters across to another drive is all perfectly possible.

Lots of people seem to be guessing at what is possible and what is not,  believe me,  all of the above is possible to do with some very basic tools,   I've probably not covered all the different possibilities here,  

It's all a myth,  probably created by the same people who tell me I can't replace surface mount components with a standard soldering iron,  hmm,  so this is not a DMA fixed AmigaOne I have here is it then,  must be a figment of my imagination.  

All this comes down to knowledge of what is needed to be done,  special tools,  expensive clean rooms,  all a big money making con
 :-)

[amigaoneproductions]

when HDToolBox maps out a bad block or low level formats a hard disk, is this updated information stored somewhere on the platter or in the drive's logic?

It is saved as a file on the hard drive,  I can't remember if it was HDToolBox or QBTools,  but one of them creates a file called bad.blocks, that file just uses those bad blocks so nothing else will try and write to them.

As for bad blocks that you never get to know about,  i.e. those that the drive maps out automatically,  thats a different story.  All drives have defects,  older drives used to have the defect list printed on them, and you would need to enter this list into your formatting software to tell it not to use those areas, but new drives do this internally and try to present themselves to the OS as perfect disks by automatically remapping spare blocks.  Only when it can no longer do this will the drive actually admit to you that it has a problem.
As for where this information is stored,  I am not sure if it's platters or logic,  anyone else know that bit ?
(I know a lot about how this stuff works,  but I don't know everything ;-) )