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Initially this drive was connected (via FireWire) to my wife's Mac (still running OS X 10.7), but she it would not mount any more and she asked me to look at it. After reading suggestions on-line, I plugged it directly into the wall (i.e., not through a surge protector), and connected it to my MacBook Pro via USB (as the Retina MacBook's no longer have FireWire). It still won't mount. If I run the Disk Utility or Finder GUIs, it does not show up there, nor does it show up under /Volumes. Initially, when I ran diskutil list from the command line, I got:

▶ diskutil list      
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         250.1 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           *249.8 GB   disk1
                                 Logical Volume on disk0s2
                                 29D0D1B5-0293-437E-B2E1-DE425E6BECAB
                                 Unlocked Encrypted
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS My Book                 2.0 TB     disk2s2

I then ran diskutil info disk2 and got:

   Device Identifier:        disk2
   Device Node:              /dev/disk2
   Part of Whole:            disk2
   Device / Media Name:      WD My Book Media

   Volume Name:              Not applicable (no file system)

   Mounted:                  Not applicable (no file system)

   File System:              None

   Content (IOContent):      GUID_partition_scheme
   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 USB
   SMART Status:             Not Supported

   Total Size:               2.0 TB (2000392994816 Bytes) (exactly 3907017568 512-Byte-Units)
   Volume Free Space:        Not applicable (no file system)
   Device Block Size:        512 Bytes

   Read-Only Media:          No
   Read-Only Volume:         Not applicable (no file system)
   Ejectable:                Yes

   Whole:                    Yes
   Internal:                 No
   OS 9 Drivers:             No
   Low Level Format:         Not supported

Naturally, seeing "no file system" was very disturbing, as this drive holds lots of media that is personally important. I should point out that this has always been a Mac-only drive.

After a little time elapsed (while I was doing more research, as I was writing this question), I ran diskutil list again, and now the drive does not show up there, either:

▶ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         250.1 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           *249.8 GB   disk1
                                 Logical Volume on disk0s2
                                 29D0D1B5-0293-437E-B2E1-DE425E6BECAB
                                 Unlocked Encrypted

If I unplug the USB at this point, the drive goes silent. If I plug it back in again, it shows up in diskutil list. I then quickly ran the Disk Utility app, and it showed up there, as well. At this point, I clicked on the Verify Disk button, and after a little time:

Verifying partition map for “WD My Book Media”
Checking prerequisites
Problems were found with the partition map which might prevent booting
Error: Some information was unavailable during an internal lookup.

I went back to diskutil list, and sure enough it was gone from there again. So, I repeated the unplugging/replugging step, went back to the Disk Utility app again, and this time clicked on the Repair Disk button. It's been a while since anything has changed on the output for Disk Utility. Here's the current output:

Verifying and repairing partition map for “WD My Book Media”
Checking prerequisites
Checking the partition list
Adjusting partition map to fit whole disk as required
Checking for an EFI system partition
Checking the EFI system partition’s size
Checking the EFI system partition’s file system

I'm not quitting the app, and the drive still shows up under diskutil list, so that's something, but I'm not expecting any progress here, so I appreciate any other suggestions. (I'll update this question if/when I do see progress in Disk Utility.)

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  • If you don't have a backup, right now I'd be looking at recovery rather than 'fixing' it
    – Tetsujin
    Jan 10, 2015 at 17:51
  • Would recovery involve removing the platter and attaching it to a different controller, or are there less invasive options? Perhaps naîvely I felt that using Disk Utility's "Repair Disk" option would be safer. Jan 10, 2015 at 17:54
  • eek, not if you ever want to see the data ever again;-) I meant something along the lines of Data Rescue not any kind of physical dismantling, which needs an industrial 'clean room'. If the data is important enough, & you have no backup, then there are companies that specialise in dismantling & rescuing the 'hard way' … but they charge appropriately [think hundreds or thousands] & still won't guarantee anything.
    – Tetsujin
    Jan 10, 2015 at 17:57
  • It seems like using Data Rescue will require me to order the BootWell drive and wait for its arrival. Instead, I've reached out to a local repair shop for their 2¢. Meanwhile, I've clicked on the Stop Repair button, and the message "Stopped by user" was added to the screen, but it doesn't appear to actually have been stopped, and if I try to close Disk Utility, I get an ominous message that operations are still in progress. Eventually, of course, I'll have to quit or try disconnecting the drive first. Jan 10, 2015 at 18:19
  • you don't need a boot USB if you're trying to fix an external drive, so long as you have room to save the recovered data to, you're ready to go from a working system.
    – Tetsujin
    Jan 10, 2015 at 18:21

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