Is it possible to boot or Time Machine restore from an external Thunderbolt disk drive?
(There are several questions - search for "?".)
I purchased a Seagate Backup Plus for Mac Desktop Drive 3 TByte with default USB 3.0 interface, and also acquired the Seagate Thunderbolt Adapter for Backup Plus Desktop Drives and Thunderbolt cable.
I do a redundant backup to the Seagate Drive using both Carbon Copy Cloner (nightly) and Time Machine (hourly) using its Thunderbolt adapter. BTW: One never knows when Time Machine will choke - see discussion titled, "UPDATED: Serious Time Machine bug on Mountain Lion", which I had; Rest In Peace Pondini (James Lewis Pond).
Booting from the external Seagate Backup Plus via Thunderbolt inteface from System Preferences -> Startup Disk:
I select the Time Machine OS X, 10.8.5 Startup Disk (Thunderbolt attached drive), click Restart, confirm my choice, the computer reboots, however, it reboots from the internal Macintosh HD OS X, 10.8.5, NOT the selected external Thunderbolt drive. The SSD drive was used as the Startup Drive, not the selected external Time Machine volume as indicated by the display free disk space command (df(1)) and seeing that the Macintosh HD OS X, 10.8.5 volume is mounted as root. That is very deceptive in that both the internal and external drives will appear in the same manner from a GUI point of view! OS X doesn't even inform me that it did not boot off the selected volume. This is the first half of the problem, that is, Is it possible to boot from an external Thunderbolt disk drive? In my case, the answer is deceptively No. Can anybody else boot off a Thuderbolt attached disk drive? Note that if I remove the Thunderbolt adapter, and attach the drive via its USB 3.0 cable, the MBP boots off the external Seagate Backup Plus just fine, as is expected.
Booting from the external Seagate Backup Plus via Thunderbolt inteface from boot-time "Option - Select startup disk" method:
When I restart the MBP using the startup Option key to select the startup volume, the externally connected Seagate drive ONLY SHOWS UP if it is attached with the USB 3.0 cable, not when it is attached with via the Thunderbolt interface. Can anyone else boot off a Thunderbolt drive with the startup Option key sequence? At least the MBP doesn't deceive me in this case - I know right away that the external Thunderbolt drive is not an option when connected as such.
Time Machine restore from the external Seagate Backup plus via Thunderbolt interface from the "command-R - Recovery Parition" method:
After booting from the recovery partition, I attempt to perform a Time Machine restore from the Thunderbolt connected Seagate Backup drive. When Time Machine attempts to present me with a viable backup Time Machine volume, the external Thunderbolt drive is never offered as an option. So I switch the Time Machine volume to use its USB 3.0 interface, and then Time Machine displays that drive as an option, and the MBP proceeds with the restoration as expected. The interesting thing to note is that while booted in the recovery partition via the Thuderbolt cable, the MBP Disk Utility may be selected, and the Thunderbolt attached drive may be operated on just fine. Can anybody else restore their MBP using Time Machine and the Recovery Partition via the Thunderbolt interface?
This is also a big problem for me in that I am forced to restore my MBP via Carbon Copy Cloner using the USB 3.0 interface, because I cannot even boot off that volume's Thunderbolt interface. Of course, the option may be that I could use yet another eternal USB 3.0 drive, boot from it, and then use Carbon Copy Cloner to restore the Macintosh HD via the aforementioned drive connected by a Thunderbolt cable, but that is less than ideal and not elegant, so I'm not going there.
Another side issue is that the commercially available program, TechTool Pro 7's eDrive, which I installed on the Time Machine volume, will not boot off that eDrive as advertised, but I won't got through those steps here, because that would be beyond the scope of this issue, however, I must say, It does not work either when the Time Machine volume is connected via the Thunderbolt interface, but works just fine when connected via the USB 3.0 interface.
MacBook Pro with Retina display, OS X Mountain Lion (10.8.5)