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My iMac no longer recognizes external firewire WD drives.

This has occured twice in the past few months. The first drive was a WD My Book Studio 2TB configured as Raid 1. The more recent occurance on a WD My Book 4TB configured as Raid 1 and housing iTunes :-( The later occurred after loading the latest Lion Update after the iMac rebooted. Error messages say neither of the drives are recognized. Based on my thought that the issue might have been generated by the drives not properly being dismounted on a shutdown, I swithed the drives over to a PC, successfully mounted them, and then dismounted them. They are still not recognized by the iMac. The Disk Utility gives me an error regardless if I try to mount or dismount the drives despite it indicating the drives are not mounted. The iTunes drive is backed up as well as the Mac; but, I do not know what to do to fix the WD drives and I am especially leary of connecting anymore firewire drives since this appears to be hapening way too often and I do not know why. Any help from a great sage would be greatly appreciated, especially if I can recover the two drives.


Thanks,Glenn

iMac (24-inch), Mac OS X (10.7.3)

Posted on Feb 8, 2012 2:00 PM

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Posted on Feb 8, 2012 3:25 PM

Try resetting the SMC.


SMC RESET


  • Shut down the computer.
  • Unplug the computer's power cord and ALL peripherals.
  • Wait 15 seconds.
  • Attach the computers power cable.
  • Wait another 5 seconds and press the power button to turn on the computer.



PRAM RESET


  • Shut down the computer.
  • Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  • Turn on the computer.
  • Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
  • Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  • Release the keys.
8 replies
Question marked as Best reply

Feb 8, 2012 3:25 PM in response to GRK_Astronomer

Try resetting the SMC.


SMC RESET


  • Shut down the computer.
  • Unplug the computer's power cord and ALL peripherals.
  • Wait 15 seconds.
  • Attach the computers power cable.
  • Wait another 5 seconds and press the power button to turn on the computer.



PRAM RESET


  • Shut down the computer.
  • Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  • Turn on the computer.
  • Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
  • Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  • Release the keys.

Feb 13, 2012 10:34 AM in response to rkaufmann87

SMC Reset fixed the issue with the iTunes, 3TB drive, but the 2TB drive seems to be hopelessly in la la land. PRAM Reset did nothing. At last the more improtant drive was recovered. I cannot even reformat the 2TB since it will not mount or dismount. Maybe if i apply a little string theory and work in the 10th dimension.


Thanks for the help, Mr. Kaufmann. -- Glenn

Feb 13, 2012 2:36 PM in response to GRK_Astronomer

Here was the final solution to the WD MyBook Studio 2TB and 3TB drive (quad interfaces: Firewire 800, Firewire 400, USB 2, and eSATA) non-recognition problems:


rKaufmann87 Suggested SME and PRAM resets. The SME reset resolved the issue with the 3TB drive only. PRAM Reset was done, 2TB still not recognized by iMac or separate MacBook Pro.


I finally got the other drive backup in a distructive manner.


(1) Connecting up via firewire 800 - Not Mounted, could not dismount, could not verify, could not erase


(2) Unplug Firewire 800, reconnect as USB - Drive Not Mounted, could not mount or dismount; however, I was able to erase the drive. Drive automatically mounted after erasure.


(3) Dismounted Drive, disconnected USB and reconnected via Firewire 800 - 2TB Drive now automounts again.


It seems strange that I was not allowed to format (erase) the drive via Firewire 800 connection; but, was able to do so via USB 2 connection. This method obviously results in the loss of data on the drive, but effectively corrected the mounting issue. Fortunately, this was just a general drive and was already backed up before the incident of not being able to mount it.

Feb 13, 2012 2:45 PM in response to Rudegar

Rudegar,


Is the drive the WD MyBook (Black single disk) or WD MyBook Studio (silver dual disk) ... two different drives with the latter being Raid configurable as Raid 1 only (Mirrored).


It does sound like there was a power supply issue with yours in any case. My drives could be turned on; they would just not automount anymore.


I do have the black 1 TB MyBook and also a 1TB MyBook Studio and have not had any issues with those.

Aug 21, 2015 9:54 AM in response to rkaufmann87

Thanks for this post. I was having a similar problem on a iMac 21,5" end 2009 on which I was connecting a WD My Passport Ultra external drive. That was recognized temporarily from the system but immediately starting to get a RAID Error and then after a while disconnecting the drive. I was trying several things to adjust this but nothing was looking to be successful until when I was following the SMC reset procedure stated in your message. Now drive looks to run without any issue. Just for info the drive was connecting only by USB. Hoping that this may be helpful for someone else. Ciao e grazie!

My iMac no longer recognizes external firewire WD drives.

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