Problem: Lost, Erased, or Corrupted Partition Table on External Hard Drive.
Seagate External Hard Drive
1TB Seagate Expansion Portable Drive
*Used only for my time-machine back up for my Early 2011 Macbook Pro.
Early 2011 Macbook Pro (13-Inch, 2011)
2.7 Ghz Intel Core i7
16 GB Memory
*Swapped out the Optical Drive for an SSD.
Storage Drive 1TB
SSD 128 GB
Problem Started Here:
-Picked up a New Apple MacBook Pro w/Retina Display 13.3" Display - 8GB Memory - 256GB MF840LL/A Laptop. Powered it up, and plugged-in my Seagate External Hard drive, (I believe Yosemite was the OS on this) Anyways in attempt to eject correctly; the eject Failed, and with haste I unplugged the Hard Drive. By this time, I had re-formated my Early 2011 Macbook Pro. My intention was to restore from my time machine backup on the Seagate, but when I attempted the restoration, the Hard Drive was not mounting, or even being recognized by my Mac. I verified any sign of the Seagate with
- System Information
- Disk Utility
Troubleshooting Attempts
- Went to the Local Frys picked up.
1. USB 2.0 to IDE/SATA/2.5"/3.5" Hard Drive converter
2. USB Y Cable for External Hard Drive - Dual USB A to Micro B
I attempted the following with the following results.
1. Remove HD from Enclosure and connected via SATA, but nothing changed. The lights on the hard drive didn't even light up.
2. I placed the HD back within the enclosure, and used the Dual USB A to Micro B Cable. Hard Drive Powered, and was spinning. (Only possibly with 2 USB). At this point. I went back to the Disk Utility and the System Information Panel and noticed the system has recognized my Seagate HD but it appears to have a Lost or Corrupted Partition Map Type.
Here is the System Information
Capacity: 1 TB
Removable Media: Yes
BSD Name: Disk3
Host Controller Driver: AppleUSBEHCIPCI
Partition Map Typ: Unknown
PCI Device ID: 0x1c2d
PCI Revision ID: 0x0005
PCI Vendor ID: 0x8086
Disk Utility Information
Left Sidebar indicated an External Drive: Seagate Expansion Media BUT there is no partition (Indentation Underneath).

Also these are the only available options, the rest have been greyed out.
-First Aid (Works but is of no benefit)
-Erase
-Info - listed here.

So I proceeded to Terminal Command and tried the following with their respective results.
1. Diskutility list - Listed the drives with the same information as the DiskUtility Utility.

2. Sudo Pdisk /dev/rdisk3 - Prompted Password. Password Entered, and the following was returned.
"pdisk: Can't read block 0 from '/dev/rdisk3'.
3. Sudo Fdisk /dev/disk3 and returned the following.

4. Sudo got recover /dev/disk3 - Entered the Password and the following returned.
"gpt recover: Unable to open device '/dev/disk3': Resource Busy
5. Sudo lsof /dev/rdisk3

6. Unmounted and Mounted (At this point I've run out of options. I tried to Mount and Unmount the Drive).
Unmount via : "sudo diskutil unmountdisk force /dev/disk3".
Result: Forced Unmount of all volumes on disk3 was successful.
Mount via: "Diskutil mount /dev/disk3.
Result: Volume on disk3 timed out waiting to mount.
7. Sudo diskutil repairdisk /dev/disk3

I can't get the drive to to do anything without timing out or without a greeting from a Pread error resources busy. I have picked up the following tools.
Disk Drill
Test Disk
Disk Warrior
R-Studio
Easeus Data Recovery Wizard
Photorec
While my Hard Drive isn't visible on most of these, all except for R-Studio, Photorec, & Disk Drill. I can see the drive in Disk Drill, but I keep getting the Disk Drill Log keeps showing the following error: 12/21/15 12:24:47.824 PM Disk Drill[515]: timeout read from offset 1048576, reopen disk handle.
Photorec shows a unpartitioned Raw File without any structure to it.
Any initiative is timed out or stuck because the systems resources are busy. The drive will not read or write. Looking for some help troubleshooting this drive in hopes of salvaging the data on there. Any experience and help would go a long way.
Thanks!