Internal Hard drive not recognised

[Tinhare]

I've seen many threads on this and solutions. Unfortunately none help.

To cut a (very) long story short.
I have two MBP's both 13" 2011 models. MBP(a) failed to recognise HDD. Tried usual diagnostics but could see drive.
Thinking HDD failure but just to be sure took drive out of MBP(a) and installed it in MBP(b). Sure enough it booted up just fine. Which was handy as wife could continue to work.
Which made me think that there was a fault with MBP(a) itself. So, to confirm i put the HDD from MBP(b) into MBP(a). It also booted just fine. Hmmm.
So now we have both MBP running but with the HDDs swapped about.
Sooo, once the wife had finished her work I swapped the drives back to their correct machines.
Once again MBP(a) failed to boot but MBP(b) worked fine. Grr. Swapped the drives back again to confirm and yep, sure enough when the drives are swapped (i.e. drive from MBP(a) in MBP(b) and visa versa) all is great and both machines work.

So, basically MBP(a) will not recognise its HDD but will MBP(b)'s. MBP(b) will recognise and boot of either.

Doing my head in as there is no logical explanation as far as I can see.

Any thoughts?

(oh, that wasn't that short was it).

Thanks,
Alan.

 

[Tinhare]

Wow, the response has been totally underwhelming.

 

[AlphaDogg]

Wow, the response has been totally underwhelming.

You'll fit right in here at macrumors...

What troubleshooting steps have you done so far? Disk utility? Holding option at boot? Repair volume? Repair permissions? We need more information

What kind of hard drive? WD? Seagate? Hitachi? SATA 2 or SATA 3? Stock drives? What operating system are you running?

 

[Weaselboy]

Wow, the response has been totally underwhelming.

I suspect the reason you have gotten a response is nobody has a clue what is wrong with your machines. I recall reading your post a couple days ago (I actually read through it twice to understand) and could not think of anything that might cause this.

The drive cables do go bad in these, but that would not explain why MBP(a) won't work with its own drive and does with the other. I suppose it is possible the cable is starting to go and something about the brand/internal design of the one drives causes it to fault while the other drive does not. Maybe buy a new cable for A and see if that helps? I think they are only ten bucks or so on iFixit.

 

[Tinhare]

Thanks to you both for your replies.
Alphadogg,
Tried Disk Utility after doing an Option boot on MBP(a) but the hard drive wasn't showing up in Disk Utility. So made any other DU options null and void.
However, when I swapped the drives over I did use DU on MBP(b) with MBP(a)'s drive in it. Was able to verify disk, nothing found.
Repair button was greyed out so assumed nothing to repair. Happy to be corrected on that one.
Also verified the permissions and did a repair on them.
Both drives are stock 750Gb drives. Hitachi I think from memory.
Both machines are running OSX 10.9

Weasleboy,
My thought also was that the cable could be faulty but as you said it doesn't explain why the other drive works. If it did work after the swap you'd expect it to fail again shortly after. It's been six days now and MBP(a) has been running fine with MBP(b)'s HD.
As for brand of drive etc, they are the stock 750Gb drives. Same brand etc etc.,

The only reason I posted was because it was such a weird scenario and thought that maybe, just maybe, someone had seen something similar.

Makes you wonder though, if other people have had HD or cable "failures" but they were't failures at all but a similar problem to mine but they didn't have access to another machine to test it out.

I wonder how many average, non-technical users have had their hard drives replaced, as obviously replacing the HD solved the problem, when in fact it wasn't faulty.

Thanks again,
Alan.

 

[duervo]

Put the drives back in their own systems and just swap the cables.

 

[Tinhare]

duervo,
What a great suggestion. I'll try it later when I have time. That would verify if it is a cable issue.

Thanks,
Alan.

 

[pragmatous]

I've seen this before. On a PC. I think it had to do with the BIOS version. Are both macs up to date with the latest firmware? I'm well aware macs don't have a BIOS but it does have firmware.

If the cable doesn't work try and do a system update on it. Make sure they are both update.

The cable swapping is a good idea too. I just think the firmware is older than the other mac and the mac with the older firmware can't recognize the drive.

I don't think it's the cable because then none of the drives would work. I would think anyway.

But who knows I've been wrong on many things before.

duervo,
What a great suggestion. I'll try it later when I have time. That would verify if it is a cable issue.

Thanks,
Alan.

 

[Weaselboy]

However, when I swapped the drives over I did use DU on MBP(b) with MBP(a)'s drive in it. Was able to verify disk, nothing found.
Repair button was greyed out so assumed nothing to repair. Happy to be corrected on that one

That is not normal. Whether it needs repairs or not you should be able to run repair disk. Double check on both systems in DU and confirm with the same selections one has repair disk greyed out and the other does not?