Faulty HDD

[Hawkery]

So my hard drive is faulty and it wont boot. I managed to find access to Terminal and run a few disk checks though it didn't seem to recognise there was even a disk in existence. Opened it up and the connector seemed okay, plugged in a new hard drive and it's working fine and now downloading Yosemite.

I'm planning to put the old one back in and see if Disk Utilities can do anything (I believe there is a disk utilities stored on some kind of internal heard drive to the motherboard, so that when hard drives break users can run diagnostics if anyone can confirm?)

My question though is how easily can hard drives be repaired - if at all? I could probably add more detail once a few more checks are done but does this sound like a recoverable drive?

Thanks in advance

 

[poiihy]

The disk utility thing you mentioned is the recovery partition. It is stored on the hard drive so if the hard drives breaks, you cannot use it; however if you have a newer Mac then it would have Internet Recovery which would download a recovery OS from the internet (Apple's servers) and run it.
http://support.apple.com/en-us/HT4718

It is very difficult to physically repair a hard disk and it should not be done on your own. Hard disk drives have very extreme precision of the read/write head. It's the equivalent of flying a passenger jet 5 inches off the ground, and varying by only a millimeter. (Although at such small sizes physics are different so it does not match). You should have a professional data recovery service do it for you. If you do it yourself then you may almost certainly destroy it further.
This is if the actual hard disk drive part is damaged, like the actuator arm or the metal disks (the actual "hard disks").

If the actual hard drive part is actually not damaged then you can probably recover your data rather easily. Sometimes the connector just goes bad. Other times (rare though) the logic board itself may go bad. I think it is unlikely it is this because you put in another hard drive and it worked. You could try putting the HDD in an external enclosure but I don't think it would work.

Listen to the hard drive. If it makes a repeated loud clicking repeatedly at even intervals then it would be a bad hard drive itself and would require data recovery.

 

[Fishrrman]

Rather than "put the old drive back into" the Mac, if you want to work on it, you might consider one of the following:
- USB3 external enclosure
- USB3/SATA docking station
- USB3/SATA dongle
These run about $25-30 for the enclosures or docks and you can get a dongle for around $20.

This way, you can just put the drive into an enclosure/dock/dongle, then connect it, then test it.

If Disk Utility is able to re-initialize it, then test it using the "repair disk" function. If the first test is good, repeat it about five times. If EVERY test is good, I would then use the drive for "scratch" (non-essential) storage.

Even if the drive is bad, you can still get ANOTHER drive, and use it with the enclosure/dock/dongle as a backup, etc.