[ILUG] disk recovery

[Paul Murray]

Niall O Broin wrote:
> On 12 May 2009, at 14:28, Paul Murray wrote:
>
>> Two points to note with that tactic:
>>
>> 1) Remove the controller board first
>
> Why? You could well have a heat related problem on a controller chip.

Because if you get condensation on the controller chip, you WILL have a heat 
problem on it ;-)

Theres chips on both sides of a controller board, so you can't exactly see 
if they're wet, and rubbing them with a towel isn't the best advice either.

>> 2) Use it as a last ditch attempt because if the drive isn't dead,  the 
>> condensation inside after it warms up will kill it, you've only  got one 
>> run left.
>
> Do you mean inside on the platters? I doubt there's any significant 
> amount of water vapour in the platter housing. I've heard people  mutter 
> about the condensation issue numerous times, but in my  experiences I've 
> never seen condensation occur. Also, I wonder would  condensation matter 
> anyway? Condensation will be very pure water, and  pure water is an 
> insulator, so where's the problem? [I suppose the  water could rapidly 
> become impure due to e.g. dissolving some  microscopic amounts of dirt 
> from the controller but bottom line if  that I've never seen this cause a 
> problem]

Yeah, you hear all kinds when it comes to HDD recovery, like how drives are 
hermetically sealed and that if you open the cover you'll kill the vaccum, 
despite there being an airhole on every hard drive casing cover. Its one of 
these taboo areas where everyone, including myself, is an f**king expert.

Pure water running inside an airhole will pick up dirt and grime en route 
and become impure.

Condensation does not only happen going from hot to cold, ie, in the freezer 
where the moisture is "pure", but also going from freezing to warm which 
absorbs impure moisture from the environment.

>> The coldest I've ever had to recover a drive from was from a PC left  in 
>> the boot of the car on a frosty night, and yes, the cold does  work, just 
>> freezing it should only ever be a last resort as it will  kill the drive 
>> and kill all remaining attempts.
>
> On one of the drives I've recovered, I had to use two freezing cycles,  as 
> I wanted all the data back, and the drive had heated up again  before I 
> got all the data.

Running under a desktop fan on the drive has achieved the same result for 
the 150+ or so drives that I've recovered from in the past 5 years.

> I really don't know where you get this  "cold will kill the drive" idea - 
> have you actually had this happen?  And if you say you have, how would you 
> really know, as the drive was  presumably dodgy anyway.

Water will kill the drive, not cold, you want mechanical parts to seize up, 
sure, water soak them. Want to do it accidentially, sure, freeze them.

Done my first failed hard drive recovery 8 years ago, and the only one that 
has completely failed since then was an unattended recovery that took place 
the day my desktop fan gave up the ghost. By desktop fan I'm talking about a 
fan that sits on your desk in a computerless office rather than a fan that 
goes inside a desktop chassis casing.

As a rig for doing it, I recommend an IDE / SATA expansion card so that you 
can trail the leads out of the side of the case rather than mounting the 
suspect drive in the case, makes the cooling job so much easier. Heat is 
your enemy, cool is your friend, in my experience, you don't need to freeze, 
just keep the sucker cool.

YMMV,

Paul