I bought a WD MyBook 500GB to back up my two internal drives that I have had for over 4 years each. The backup went smoothly over Firewire at a respectable speed and everything was fine for months and months.
"What is going on? Did the heat in the external enclosure damage the drive?
It is impossible to say for sure, as we can't for sure say if the heat is a symptom or a cause. I would tend however to support your thesis, though, as heat affects magnetic properties of materials.
Although it is unlikely that your HD reached any close to the curie temperature, heat can still weaken the magnetic proprieties of materials, as cold improves them. It might be (but this is just an hypothesis) that the magnetic proprieties of the disk surface or of the writing heads have weakened.
Also, heat can have deformed the physical shape of some component, making them less effective (for example a writing head which is now further away from the disk surface).
A test you could do is to wrap your HD in a watertight plastic bag and immerse it in a bowl of crumbled ice (even better: you can mix the crumbled ice with salt, that brings the temperature down to circa -21°C) and repeat the tests there. You might notice an increase of performance.
Incidentally his is a technique that - through contraction of the materials - is also useful to unstuck movable parts (which does not seem your problem, as normally a stuck movable part means no read and no write capabilities at all).
Another common cause of disk failure is vibration. Vibration brings lack of precision in the moving parts, tear of joints, wrong alignments between heads and disk surface, and so on and so forth. In case something is now impeding the disk to revolve smoothly, you would for sure have extra heat generated by both the friction and the increased power used by the engine to keep up the rotation at the same speed. In this scenario heat would be a symptom rather than the cause of your problems.
Why can I still use the drive without any problems other than a slow write speed?
With a metaphor: for the same reasons for which you will go faster on a well lubricated bicycle than on a rusty one. Modern hard drives are smart enough to compensate for hardware problems, so - unless a core component is broken - they will find a way to keep running (this is so because HD's obsolete very quickly, and if they would stop working at the first writing error or corrupted sector, you would be changing your HD every few weeks).
What is going on with this SMART Status and what does that Quick Test result mean?
Unless you find some official documentation, this is a question one might only infer the answer to. You can pick your favorite one: from marketing reasons (so you do not immediately notice defects!) to human mistakes (it's just a bug, it should report ""not passed"") transiting by design ones (""pass"" means the HD is still usable, the test that fails signal the fact a non-essential subsistem is broken)
Should I expect this drive to die on me any second?
Again: you can never know for sure. I have still a 5 Gb unit from the 90's up and running, for example. But consider this: you normally would keep backups of a totally healthy HD because it might - all of a sudden - fail. Now, you have an HD with visible signs of bad health status, heating up like crazy, having degraded performance and failing tests... if I were you, I would definitively hope for the best but prepare for the worst!
Hope this helps, and if you try the cryo trick (the ice thing) I would be very interested to know the outcome of it. Best luck!"
"I would bite the bullet and get another hard drive. That 500GB drive sounds like it may fail at any moment and you shouldn't waste time trying to eek out another few months of service. If the data on that drive is that important to you, surely it's worth $50 for another drive.
If you value your data, backups are important. Don't skimp on them. Get yourself a good hard drive enclosure. I have one made of solid aluminum with USB, FW400, FW800, and eSATA ports -- it cost me about $90. I put into it hard drives with five-year warranties. I replace them every 18-24 months. I also subscribe to an online backup service for about $5/mo. My data is backed up in at least two places, both onsite and offsite.
As I said in one of my comments, the manufacturers of cheap external hard drives don't expect them to last very long. And they really don't expect consumers to claim warranty repairs, either. They'll just replace your broken drive with a refurbished one, anyway.
I know it's hard to differentiate one product from another. The temptation is to go for whatever is cheapest, figuring that the quality must be all about the same. And you're right: for the cheap stuff the quality is all pretty equally poor. Unfortunately, cheap crap is sometimes the only thing available -- the good, quality stuff having been long ago put out of business."
The problem is most likely to have caused by overheating of HArd disk!
Use HDD scan to analyze any errors in Hard disk! Also you can measure you HDD temperature! In most cases, WD mybook would have problems with temperature!
http://hddscan.com/
And another issue: You say u have slow transfer rate!! use the chkdsk /f command to correct some sector problems!
For backing up crucial data: I suggest you upload to an online server/FTP/file-hosting service/skydrive etc... ( IF you have unlimited bandwidth package )
OR
Write datas to DVDS/ CDS and keep then in a SAFE PLACE!
Good luck!
EDIT:
You could try mounting it on the casing and check for any speed improvements ( keep the HDD casing holes near a fan )"
Try connecting to a different USB port. If that doesn't work, back up everything to another drive, since read speeds are ok, then start playing with the drives. When connected with SATA, try a different port, cable and/or computer.
