External Clone won't boot
 

OS X 10.12.5
I'm selling my iMac (2012 - 27" i7) Fusion Drive (all SSD)
Successfully copied HD to External backup (non-SSD). All green indicators.
Erase the SSD drive via Disk Utility on my Repair partition.

When I restarted the Mac holding the option key, the Clone did not appear, only the EFI boot.

Plugged in the external to my MacBook Pro (also 10.12.5). Clone HD shows up in my System Preferences>Startup Disk panel, however, when I chose that as my Startup Disk, it subsequently fails to boot, reverting instead to the MBP's startup disk. As an alternative, held down the option key on the restart. Only the MBP HD appears.

I have never had a problem booting from a SuperDuper cloned drive. Any suggestion about what else I can do. Thanks for the help.

Try using a USB2 cable (which will fit in 1/2 the port) rather than a USB3 cable.

(I have no idea what an "all-SSD Fusion Drive" could possibly be, because that's sort of totally not what a Fusion drive is, but the type of drive doesn't matter. We're working at the file level, not the "physical drive" level.)

Thanks for the suggestion Dave. Don't have a USB 2 cable for the WD drive. Tried the cable from another WD drive and a Seagate drive (both USB 3). No change in behavior. Strange I can see the drive in my Startup Disk Panel but won't boot on the restart.

Wondering if I could remedy by cloning the HD to another drive?

Regarding the Fusion Drive. The original conventional HD started showing signs of failure about 6 months ago. Purchased a 1TB drive and had certified Apple rep do the install. He said installing the SSD would not change the Fusion behavior.

That's why I'm suggesting a USB2 cable. Let me suggest getting one that fits (either microUSB or regular USB depending on the drive).

Really, using SSD on both sides of a Fusion drive is kind of crazy, since the whole point of it is to use SSD to cache frequently accessed blocks. If both drives are fast, it doesn't do anything except make things more complicated.

I don't think 2.0 USB micro cable can fit into a WD HD 3.0 micro slot. The 3.0 cable has 2 joined sections, where the 2.0 cable has only 1. Could you clarify please? Thanks

Regarding Fusion Drive, the machine's general operation proved much faster than its original state. Open/Save file time was much faster too. Also, never noticed any operating oddities. Prior to making the decision to switch to the 1TB SSD by OWC, I consulted both an Apple certified repair guy, plus an upper tier Apple tech rep. Both thought the combo would work without issue. Said the interaction of the 2 drives would be seamless from a user perspective.

The micro cable fits in 1/2 the slot. A USB 3 port is a standard USB 1/2 port plus an extension.

I'm just saying that simply operating off the straight up SSD would be the same speed as the "fusion" SSD+SSD. It's a weird setup that doesn't make much sense. That's all.

Oh...I see. Thanks. Once I get the cable, I'll post back and let you know if I could boot via the clone.

Earlier in this thread, I asked if I could make another clone from the one that won't boot. Thoughts?

I thought so too. That's why I consulted Apple re options.

Yes, you can make a copy from the copy.

That may be my only out. Tried the USB 2 cable, however, drive did not boot. Thanks again for your help. Appreciate it.

Did it act any differently?