External Enclosure - Odd

Ok guys I have a real mind boggling crazy thing here....

I fired up my external 750 GB drive to do the usual backup of my important data and it showed up as unusable/unformatted and 1.4 TB. Wtf? It would not work. I rebooted the drive and it showed up as 115 GB this time and still.... unformatted. Again, wtf? :/

Further reboots resulted in nothing, not even showing up. I booted my 250 GB and it worked just fine over and over reboot after reboot.

So I *swapped the drives between the enclosures* and the 250 was the one now not firing up, the 750 firing right up with no problem. Then another few reboots later both drives fire up just fine But, the 250 Wasn't advertising incorrect drive sizes..... I did even further testing by swapping the ports back and forth they are plugged into in the back of my Mac and both still work fine. So I kinda ruled out a couple problems there I guess.

Both HDDs are Western Digital drives. A 4-Year old 250 GB standard hard drive and a new 750 GB 'Green Power" HDD around 8 Months old, same exact model 750 is in my Mac.

Both enclosures are exactly the same model, they are very nice Aluminum Sabrent cases for SATA and/or IDE (both connections inside) as well as a choice of USB or eSATA for external connections to PC. Furthermore both of these cases are brand new.

Attached below are some screens. These were take a few minutes after I fired up my 750 for the usual data backup from my Mac OS X side. Note I underlined "Master Boot Record" for the 115 GB picture. This is because this drive is was not FAT32 or NTFS, it was Mac's HFS at the time of the malfunction. The HFS formatted drives use "GUID Partition Table".

So what do you guys think? Write off as a defective enclosure controller board? I know most of you guys probably don't know a lot about Macs or care to but were using some common mac and pc components here (Sata, USB..etc..), only thing different is the drive's File System and the OS X disc utility.

I think you need to contact Western Digital after double checking your USB port and cables.

I've been playing with it on and off the past hour while I do other things and my 750 is staying up and running in the other "good" enclosure, the 250 is obviously still in the enclosure in which the 750 was in producing errors, it also seems fine, but I dunno. When I first swapped the hdds within the two enclosures, the 250 seemed to produce the same errors the 750 was and the 750 was running and starting up as well as the 250 had been. I want to say it was the enclosure, But I'm going to see what happens in an overnight backup.

I'd send WD a support ticket, but I'm positive they will tell me to do everything I have so far and since my first post I'm much more confident that we have here either a bad USB cord, usb port on my mac or a bad controller board in the enclosure.

Actually, I'm running one more test right now and I'll post the result of it.

based on the info thus far I'd guess that it's the external enclosure sata controller that is messed up... it might be easier to just buy a second enclosure for +/-$20 rather than try to send anything for RMA.

It seems pretty obvious to me. There was probably a bad connection in the "bad" case, such as a connector not fully inserted, or dust/dirt/oxidation on a contact. Disconnecting and reconnecting the drives probably cleared out the dust/dirt/oxidation and/or the connections were fully mated. I wouldn't worry about it unless it happens again.

If it happens again, you might want to check if there seems to be any bad connections or cracks on the circuit board in the case.

P.s. - I've also seen weird problems arise because of a bad master/slave jumper on a drive (hard or optical), but it's rare. And, of course, since it's SATA there may be no jumpers at all on the drives. But if there are any, it doesn't hurt to pull them off and reinsert them just to make sure their contacts are "cleaned" too.

Hey all. I did talk to WD support and we pretty much narrowed it down to the case as well. The drive (in a known working case) keeps checking out "OK" when a disk check is run, and in the good case i did a backup of around 212 GB and they were all accounted for once on the drive. I don't use the drive that is now sitting in the bad case, often, so ... at least I do have my backup drive working properly though.