when we use the PC,the power shut down suddenly. Will the hdd's heads return to the firmware zone(or contact start/stop zone)??

Yes, they will. At least, if they need to they will. Not all hard drives park the read/write heads or have an initial starting point for them. Older desktop hard drives really didn't need this feature. Laptop hard drives and newer SATA desktop hard drives do park the heads, however.

In the event of a sudden loss of power, there are ways to park the heads automatically. You can use a weak magnet (or spring) that draws the actuator arm to a certain position, which doesn't need power. Or you can have a capacitor that purges in a power loss and provides enough electricity to park the heads. I'm sure there are other ways, as well, but these are the ones that I've heard of.

thanks saphalline！！

I have another question. when the hdd start work,the heads how to search the initial address??

The heads don't have to search. Each hard drive "knows" exactly how many bits of capacity it has and where they all are. This is built into the drive's circuitry, control chip, and firmware. They're programmed differently (by the manufacturer) according to this precise info.

thanks , Can I look for these precise info with some software??

Well, the HDD manufacturers all have their own software (on their websites) for doing drive-specific tasks, like zero-filling. But to my knowledge there's no way to retrieve all that complicated bit info from the drive itself. The manufacturers might have whitepapers on your model of hard drive if you search their website, but I can't say that I've ever been quite that curious about my hard drive before. ;)

thanks very much!!!
if i change the hdd's stepper motor,the head will can't search the right info
how to solve this program????

Wait... you mean changing the motor inside a hard drive? Or are you just talking about a program or a setting?

I mean changing the motor inside a hard drive.

That's a no-no! Hard drive motor surgery should only be done by professionals in a bonafide hard drive assembly facility. Mere mortals at home can't do it, unless you have two perfectly identical hard drives (one broken and one working) and even then luck is not on your side.

In general, once a hard drive motor is broken, it's time to get a new hard drive! ;)

thanks!!!
yes,I see I need another identical hdd,I want take my data back!!
I consider if I change the stepper motor the physic address will be change too.
I think the stepper motor and voice ciol motor can't cooprate as uasal, right??
do you think so ??

Well, you didn't change any addresses, but you did change the physiology of the hard drive! It doesn't know how to operate with the new motor because it wasn't designed to do that. And of course there's no way to tell the hard drive it has a new motor! :p

That's kind of like doing surgery on a blind person. If they suddenly woke up with different arms, would they be able to eat breakfast? :eek: Probably not without some trouble! And unlike a hard drive, humans are able to adapt to new things. But a hard drive with a new motor will just sit there and not work.

but as far as I know , if the hdd have only one plate,when pick the plate into another
identical hdd ,we can also read the data ,but we can't use the hdd after data recovery.

No, if you can get the data back at all you won't be able to use the hard drive again.

What Saphalline tried to point out earlier is that hard drives are not meant to be opened and worked on by individuals at home. They are made in an extremely clean, dust free environment, you can't come even close in your home. Data retrieval companies use a "white room" that is a highly controlled environment, dust-free filtered air, moisture control, temperature controlled closely and all that.

It's called a white room because the ones used at NASA for highly close tolerance machine work manufacturing tiny parts was a machine shop in a room with everything white, including the smocks the machinists wore. The white lets dust and metal chips from machining show up quite easily and only a meticulous cleanup at the end of the day keeps it white. (Used to have a friend who worked in one when I was a machinist)

The reason for this is the way hard drives work. The read/write head(s) float on an air cushion only a few molecules thick, created by the platter as it spins. Even a flat, smooth and highly polished disc pulls a bit of air with it as it spins, creating an airflow that acts as a cushion for the heads, but a very very thin one. If the tiniest bit of invisible dust in your house gets inside the hard drive and onto the platter, it's about the same as putting a boulder the size of your TV in front of your car. At 90MPH...

If you open up a drive at home, you'll be very lucky if you replace anything and get it to run again, and probably will not get any data off the drive at all. The only part of a hard drive that can be replaced at home and usually not sucessfully, is the controller card on back of the drive. Sometimes drives go bad but it's the controller that has a problem, not the drive itself, then the card can be replaced but it has a pretty low success rate.

If you open the drive up at all, don't expect it to ever function again and actually read any data, the average house is a dust storm compared to the environment necessary to disassemble and reassemble a drive successfully. I've opened up dead ones, and keep a platter and drive with cover removed hanging on my shop wall so customers can see how they are made. I tried one long ago and it wasn't even recognized by BIOS after reassembling. I knew it was a lost cause, lots of bad clusters but was still recognized, I opened it up, looked around, didn't touch a thing, closed it back and plugged it in...nothing...

but we can't use the hdd after data recovery.
If you recover data from a bad drive, you are correct. But if you recover data from a disk that has been erased, files deleted or the operating system has become corrupted, you can reuse the drive after proper partitionin and formatting along with adding an operating system if neccessary.

Is the point of this thread all about a drive you have that needs data recovered? If so, please explain what the problem and situation is, so we can possibly advise a course of action to recover the files. If the motor stopped working however, your only course of action would be an expensive project for a data recovery company and not something you can do at home. But if the motor spins and the read heads still work, you may luck out..

Thanks!!!May be we can greate a forum for data recovery. I am very interested in this!

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