Mac Mini Internal HD Intermittently Disappears, cant install Mojave to External SSD.....

[gpspad]

I am posting here because so many people boot there mac mini's from external SSD drives and may have had this issue.

A while back my parents mini started having problems with their computer starting up. Even when I started in recovery mode, I could not get the disk tool to see the internal drive.

I ended up getting an external USB SSD drive and installing Sierra and all was well. Things were much faster, nobody really even noticed.

Then one day I got a call that the computer was acting funning, and low and behold, I discovered the old internal HD had came back to life and was bypassing the external SSD drive.

I ended up reformatting the internal HD and just left it alone. I didn't think I could trust it anymore and didn't want it to accidentally boot up over the external SSD drive. It must have worked for a while because I managed to install High Sierra w/o any problems in August.

Yesterday I tried to install Mojave and I get an error that there is no "firmware partition". The internal HD must be dead again, no matter how I boot up or try to use disk tool the internal HD is not seen.

I have another mini and think i can trick Mojave to install itself onto the external SSD drive by plugging it into another mini, but I will be left with the same problem in the future. I am trying to avoid potential damage by opening my parents mini and installing the ssd drive. I have already broke a status light when I tried it once before.

Has anyone else dealt with this issue of a running an external SSD drive, after the internal HD has died or can no long be seen?

 

[ActionableMango]

Is the SSD from OWC?

 

[gpspad]

NO its a generic samsung ssd, in a generic usb3 enclosure.....

The Mojave update worked fine in another mac mini I use as a server, I have the same ssd drive and the same external ssd enclosure

The only difference is my parents mac mini doesn't haver an internal HD showing, the mini I use as a server has an internal HD showing

 

[ActionableMango]

The reason why I asked is that when I searched for your problem, the top results were many many people all with OWC SSD drives. It is a known problem with a documented fix supplied by OWC. Since it's not an OWC SSD, I'm not really sure what to think.

An external boot drive with a failed internal HDD isn't going to be a common scenario, so unfortunately I'm not sure anyone with experience is going to be able to answer you.

Yesterday I tried to install Mojave and I get an error that there is no "firmware partition". The internal HD must be dead again, no matter how I boot up or try to use disk tool the internal HD is not seen.

Of course I assume you can't pick a dead drive as the installer's destination, but just to be absolutely clear anyway, you are selecting the SSD as the destination for the Mohave installation, correct?

 

[gpspad]

Yes, the internal drive does not come up in the Mojave installation page or the disc tool utility or anywhere else. I guess it readonly comes up, then dies again. I have been noosing off the SSD.

I originally thought it was something I could fix with a disc utility type of tool, but I did reformat at one point when it popped up back up again. The erasing and reformatting obviously didn't last too long before it disappeared again.

I may try leaving it unplugged for a day, then starting it back up.

I wanted to avoid brain surgery on the mini, but while it appears that booting to a External SSD is a good trick, it doesnt get you out of having to put a new HD in when the original one fails.

 

[ActionableMango]

I don't understand why there has to be a working internal drive. It should be able to work with no internal drive at all.

I can only speculate about the problem, and freely admit that the following theory could be totally wrong.

The Mojave installer does an important firmware update. The installer accomplishes this by putting the firmware file in a special area on your drive, and upon reboot it flashes your Mini's firmware with that file. I am guessing that the Mojave installer, as a precautionary measure, doesn't want to put the firmware update on an external drive because if the external drive had a connection issue part way through the update, you'd brick your computer.

Assuming this theory is true, I don't see any way around replacing that internal HDD with a working drive.

Personally I'd just plop the SSD in the Mini and toss the problem HDD. I've been upgrading Minis from the original G4 all the way to the current 2014 and never had a problem adding drives and memory. But I know you had a bad experience so I understand your hesitation to do that.

 

[gpspad]

Assuming this theory is true, I don't see any way around replacing that internal HDD with a working drive.

I have come to the same conclusion and plan on trying to install the SSD, its just different when its not your computer that's going to get screwed up.

It is surprising all the external driver users haven't ran into this issue though. Common advice to my mini's HD is gone is get an external SSD. Maybe the newer OSX's have new requirements regarding the need for an internal drive.

 

[Fishrrman]

OP wrote (among other things):
"Yesterday I tried to install Mojave and I get an error that there is no "firmware partition". The internal HD must be dead again, no matter how I boot up or try to use disk tool the internal HD is not seen."

Solution:
DON'T install Mojave.

My suggestion:
1. While booted from the external, use Disk Utility to "re-erase" the internal to Mac OS extended with journaling enabled. Then run DU's "repair disk" function on it. Do you get a good report? If so, REPEAT the test 5 times. Do you get a good report EVERY time? If so, I'd reckon the drive is fine, so...
2. ... download CarbonCopyCloner. CCC is FREE to download and use for 30 days, so doing this costs you nothing.
3. Use CCC to clone the SSD to the internal drive. CCC will also offer to clone over the recovery partition, YES, you want to do this as well.
4. When done, go to the startup disk preference pane and BE SURE that it's set so that the EXTERNAL SSD remains the boot drive (it will run much faster than the internal platter-based HDD).

Oh, and again -- FORGET about Mojave for now, comprende...?

Also, explain to your parents that they will see -two- drives on the desktop (internal and external). Make sure the drives are named appropriately. Explain to them that the computers runs from the external drive, and that they should "leave the internal one alone" under normal usage.

 

[gpspad]

I'll keep the above in mind if the internal HD ever shows up.

As of now it's now showing, in the disk utility or from the command line. The internal drive has disappeared again.

I know it must have been working when I installed High Sierra, but it must have failed again after that.