I purchased a 240 GB SSD from Other World Computing (OWC) to replace my existing 120 GB SSD for my mid-2012 13" MacBook Air. I've carefully followed the OWC instructions to install the new drive, format it, and burn the old drive image to the new drive. Here's the rub: I cannot get my Mac to "see" the new drive. I've carefully re-seated the new drive three times, but when I boot into recovery mode (Boot + Command + R), the new drive is not visible the Disk Utility app.
Some other important details:
As a test, I seated my old drive back in the MacBook Air and seated the new OWC drive in the OWC enclosure. Both drives were visible. I even formatted and burned an image to the new drive in hopes that it would work when I re-seated it in the Mac. It didn't.
I spent an hour with OWC tech support yesterday. They were good. They verified that the new drive I ordered is compatible with my mid-2012 MacBook Air. We also tried to "see" the drive using Terminal (again in recovery boot), but completely struck out.
Finally, I tried a regular boot with the new drive installed and the old drive in the OWC enclosure disconnected. The screen displayed a folder containing a big question.
I stole this image from the web, but it's pretty close to what I'm seeing. I can see my old drive connected to the Mac in an OWC enclosure, but the new drive is simply not visible.