2015 iMac got circle with line through it 2 days after I moved it on boot. Computer just couldn't see the HD. HELP! (Info in comments)

[TwitchOSX]

So, a couple days after I moved my iMac I rebooted because it seemed to be acting up and on boot I got a black screen with a circle with a line through it. I looked online for fixes and ended up restarting holding command-r to get into recovery mode. Once in there I went to disk utility to try to repair the HD and it basically didn't see the hard drive. So people on reddit suggested the drive was dead. I'm not so sure about that. Sooooo, I had an external hard drive that I re-formatted using my other older mac and then I reinstalled OSX onto that drive using the original backup to the iMac. Didn't think it would be ideal booting from some random external drive but it works.

So when I finally booted up from the backup restoration, I noticed that the computer in fact DOES see the internal drive. So the computer was showing the external drive that I'm booting from, it also sees the Time Machine backup external drive AND it saw the internal drive! So I know the computer can see the internal but something isn't right. The internal even showed up in disk utility.

The computer seems a bit laggy overall because I'm booting off an external drive (a small pocket WD My Passport Ultra) which I doubt it meant for booting off of (more for data storage). So I rebooted the computer to see if it will run any faster off the external after the initial reboot from restoration and I got an error saying that one of my drives is unrecognizable and gave me the ability to ignore or initialize. I canceled that and when I got to my desktop, I noticed the computer doesn't see the internal HD anymore. Just the external boot drive and the external time machine drive. And the internal is not showing up in disk utility anymore. It's just showing "disk0s2" (APFS Physical Store disk0s2) for "Internal"

Any ideas on what I should do? It JUST saw the internal drive. But then I reboot and it doesn't show. WTF is going on here?

Any ideas guys? macOS 10.14.6. How can it be working for 2 days after I move it and then I reboot and it won't see the internal drive and then after I restore to a external drive and I boot and the computer again SEES the main internal HD and I reboot again and now it can't see the internal. I don't think I can really use the computer for what I need off this external hard drive. Either I need a better external hard drive to boot from or preferably I'd like to get the internal working right. And at this point, if I need to somehow wipe the internal and reinstall osx from scratch, I'll do that. Thanks!

 

[PinkyMacGodess]

Sounds like the boot part of the drive is corrupted. It still could be that the drive is toast. I'd be really trying to copy as much off that internal drive as I can right about now, and plan on replacing it soon.

It could still be good, but I had a drive do what you are saying, and it was an infamous SeaGate wonder of shingled technology, and was the third of that model/type to die on me. (THANKS SEAGATE! LOVE YOU, NOT!!!)

But anyway, getting everything off of it will make the low level format less stressful. But consider it on life support, with a very limited time to live, if at all... GET YOUR DATA OFF THAT DRIVE. Laggy because of USB, most likely.

BTW: Hate your sig. Really? Not cool...

 

[TwitchOSX]

Sounds like the boot part of the drive is corrupted. It still could be that the drive is toast. I'd be really trying to copy as much off that internal drive as I can right about now, and plan on replacing it soon.

It could still be good, but I had a drive do what you are saying, and it was an infamous SeaGate wonder of shingled technology, and was the third of that model/type to die on me. (THANKS SEAGATE! LOVE YOU, NOT!!!)

But anyway, getting everything off of it will make the low level format less stressful. But consider it on life support, with a very limited time to live, if at all... GET YOUR DATA OFF THAT DRIVE. Laggy because of USB, most likely.

BTW: Hate your sig. Really? Not cool...

Well, I've already got the drive completely backed up with time machine. I used time machine to restore the drive to the external drive which I'm currently booting off of. So, I'm not worried about data at the moment as I have everything. I just want to get the internal drive working correctly.

And the sig is from Family Guy FYI

 

[DeltaMac]

When you start getting boot errors (that popup during boot that asks if you want to initialize, etc.), particularly if it's a hard drive, then you can try 2 steps:
1. Replace the hard drive, preferably with an SSD. (It is failing!)
2. there is no step 2, except to reinstall and recover from your backup to your new drive. If you leave the failing HDD inside, you can find out that hard drive sometimes will interfere with booting to an external. Best plan is to remove it, and you have to open it up to do that, so replacing that hard drive with something better and faster (an SSD) will be a Good Thing™

 

[glenthompson]

If you don’t want to crack the case to install a new drive, using an external SSD will do fine. I do that on a 2012 Mac Mini. Once you have it setup and running well you could erase the old internal drive and just let it be and it won’t be recognized as a boot drive.

If you do go to the trouble of opening it up, don’t replace it with a spinning drive. It’s not worth the effort.

 

[TwitchOSX]

If you don’t want to crack the case to install a new drive, using an external SSD will do fine. I do that on a 2012 Mac Mini. Once you have it setup and running well you could erase the old internal drive and just let it be and it won’t be recognized as a boot drive.

If you do go to the trouble of opening it up, don’t replace it with a spinning drive. It’s not worth the effort.

Yeah, I really don't want to crack the case. The internal drive is a hybrid "Fusion" drive. Which is fine, and I'd rather use the internal drive than an external. But if I HAVE to, I can do an external like I am now but I think I need a better external drive than the one I'm using right now. The one Im using right now is for storage so Im sure I can get a faster one to use as a boot drive. Just not sure where to look regarding that, ie: what type of drive I should be looking at. I'm using a My Passport Ultra drive right now which is a tiny little drive. Probably not an SSD. I think it's probably a laptop drive of the spinning sort

 

[glenthompson]

Yeah, I really don't want to crack the case. The internal drive is a hybrid "Fusion" drive. Which is fine, and I'd rather use the internal drive than an external. But if I HAVE to, I can do an external like I am now but I think I need a better external drive than the one I'm using right now. The one Im using right now is for storage so Im sure I can get a faster one to use as a boot drive. Just not sure where to look regarding that, ie: what type of drive I should be looking at. I'm using a My Passport Ultra drive right now which is a tiny little drive. Probably not an SSD. I think it's probably a laptop drive of the spinning sort

Samsung T7. Attach to the back of the iMac with Velcro.

If the fusion is a 1tb model the SSD portion is too small (24 or 32gb) for much use. If it’s a 2 or 3tb (128gb SSD) model then you could break the fusion drive and use the SSD separately from the dying spinning drive.

 

[TwitchOSX]

Samsung T7. Attach to the back of the iMac with Velcro.

If the fusion is a 1tb model the SSD portion is too small (24 or 32gb) for much use. If it’s a 2 or 3tb (128gb SSD) model then you could break the fusion drive and use the SSD separately from the dying spinning drive.

The fusion drive is a 3TB. But I don't want to open the case just to screw with a fusion drive. IF I opened the case, I'd just replace the whole thing with a SSD. I'll look into that T7 though. Thanks.

 

[Fishrrman]

OP:
"Yeah, I really don't want to crack the case. The internal drive is a hybrid "Fusion" drive. Which is fine, and I'd rather use the internal drive than an external."

Hmmm....
Fusion drive.
I've seen numerous posts from owners of older fusion drive iMacs that are starting to have problems with them.

The fusion drive is actually TWO drives:
- a small SSD
and
- a larger platter-based hard drive
... that are "fused" together in software so that they appear as one drive on the desktop.

If one of the drive components starts to get flaky, of course it's going to effect the entire fusion drive.

Your problem-solving technique in your original post (creating an external boot drive) was excellent, just what I would have suggested.

What I would suggest next:
Try erasing the internal drive, and testing it.
This MIGHT clear up any errors with it.
You could then restore it and perhaps use it as a backup.
HOWEVER...
If one of the component drives is starting to experience hardware failure, it will never be reliable "as a fusion drive".

It usually seems that the platter-based portion of the fusion drive is the first to fail. Not always.
Another approach (if the HDD is flaky) might be to "break" the fusion, then use the internal SSD portion (which is actually pretty fast) as a "standalone" boot drive.

Hmmm... the HDD portion was 3tb?
Seems I remember that Apple had a recall on some of the Seagate 3tb HDDs in fusion drive models, because of premature failure of these drives. May not have applied to the 2015 iMacs, however. But if the fusion drive is getting flaky, I'll bet this is the culprit.

Finally -- perhaps the best long-term solution would be to use an external USB3 SSD as your new boot drive. Much better than using a platter-based drive for this.

Alternative:
Break apart the fusion drive and use the internal SSD component (128gb) as the boot drive.
It has the advantage (over an external USB3 SSD) of being faster.
You will have to be careful about what you put on it:
- OS
- Applications
- "Slimmed down" home folder (with large libraries stored externally).
But it could work. Even if you just set it up this way to become a second boot drive for emergencies.
You DON'T want to have the external SSD as your ONLY bootable drive.

 

[TwitchOSX]

OP:
"Yeah, I really don't want to crack the case. The internal drive is a hybrid "Fusion" drive. Which is fine, and I'd rather use the internal drive than an external."

Hmmm....
Fusion drive.
I've seen numerous posts from owners of older fusion drive iMacs that are starting to have problems with them.

The fusion drive is actually TWO drives:
- a small SSD
and
- a larger platter-based hard drive
... that are "fused" together in software so that they appear as one drive on the desktop.

If one of the drive components starts to get flaky, of course it's going to effect the entire fusion drive.

Your problem-solving technique in your original post (creating an external boot drive) was excellent, just what I would have suggested.

What I would suggest next:
Try erasing the internal drive, and testing it.
This MIGHT clear up any errors with it.
You could then restore it and perhaps use it as a backup.
HOWEVER...
If one of the component drives is starting to experience hardware failure, it will never be reliable "as a fusion drive".

It usually seems that the platter-based portion of the fusion drive is the first to fail. Not always.
Another approach (if the HDD is flaky) might be to "break" the fusion, then use the internal SSD portion (which is actually pretty fast) as a "standalone" boot drive.

Hmmm... the HDD portion was 3tb?
Seems I remember that Apple had a recall on some of the Seagate 3tb HDDs in fusion drive models, because of premature failure of these drives. May not have applied to the 2015 iMacs, however. But if the fusion drive is getting flaky, I'll bet this is the culprit.

Finally -- perhaps the best long-term solution would be to use an external USB3 SSD as your new boot drive. Much better than using a platter-based drive for this.

Alternative:
Break apart the fusion drive and use the internal SSD component (128gb) as the boot drive.
It has the advantage (over an external USB3 SSD) of being faster.
You will have to be careful about what you put on it:
- OS
- Applications
- "Slimmed down" home folder (with large libraries stored externally).
But it could work. Even if you just set it up this way to become a second boot drive for emergencies.
You DON'T want to have the external SSD as your ONLY bootable drive.

Is it possible to "break" the fusion drive based on software without messing with it mechanically? I mean, if I had to open the case to mess with the fusion drive, I'd just replace it all together. And I checked out the iFixit website instructions on how to open an iMac and it seems like things could easily be broken doing so.

 

[Fishrrman]

"Is it possible to "break" the fusion drive based on software without messing with it mechanically?"

Yes, with terminal. I've never had a real "hands on" with a fusion drive Mac, but it can be done without much trouble.
Once "de-fused" the drives will appear as "standalone" drives on both the desktop and in disk utility.

I'm wondering if even disk utility can do this now? (not sure).