2015 iMac fusion drive corrupt - 128g ssd dead - fix?

[iOperate]

Hey all,

Looking for some advice from the pros around here. I have a 2015 iMac that suddenly died and started showing the folder with the question mark on startup. I believe it was during the last Catalina update.

Booted off internet recovery and I can see the disk using Terminal - diskutil list. Diskutil cs list shows no core volumes and Disktuil ap list shows no APFS containers found.

I'm not worried about data on the drives. I can and have erased the 2 TB spinning HD with diskutil eraseDisk and was successful. Trying to erase the 128g ssd part of the fusion hangs on creating partition map at 50%.

I have tried installing Catalina on the 2tb HD but when it restarts it goes back to the question mark folder saying it can't find an OS. I'm thinking this must be because its still trying to load the blade SSD fusion drive instead of the HD. In startup disk in recovery mode I can't select the HD to tell it to look there.

So It looks like the 128g blade SSD is gone. I'm not keen on taking the whole unit apart to replace it. Ideally I'd like to just run of the 2tb secondary drive for now and if I can get that working do the HD for SSD swap on that drive and just forget about the blade. Does this seem possible?

Thanks for the advice. Cheers

 

[iOperate]

Update - I booted from standard recovery instead of internet recovery and was able to get El Cap to install on the HD. Restarted and looks like its working off the HD. The blade SSD is still visible in disk utilities. I'm thinking at this point it should be safe to buy and install a platter SSD to replace this slow HD.

 

[Nguyen Duc Hieu]

Update - I booted from standard recovery instead of internet recovery and was able to get El Cap to install on the HD. Restarted and looks like its working off the HD. The blade SSD is still visible in disk utilities. I'm thinking at this point it should be safe to buy and install a platter SSD to replace this slow HD.

Or buy an external SSD. It would be much faster than the internal HDD.

 

[Fishrrman]

OP:

Now that you can boot and run from the internal HDD, can you use disk utility to erase the internal SSD?

See if you can...
- erase it
then
- use disk utility "first aid" on it, and see what it reports.

Let us know what you find.

Agree with Nguyen in reply 3 -- best solution might be to buy an EXTERNAL USB3 SSD, make it bootable, and boot from that instead. It will be far faster than the internal platter-based HDD.

You could either buy a USB3 SSD that's "ready to go", or, buy a 2.5" SATA SSD and a USB3 enclosure, something like this:

SABRENT 2.5 Inch SATA to USB 3.0 Tool Free External Hard Drive Enclosure [Optimized for SSD, Support UASP SATA III] Black (EC-UASP)

SABRENT 2.5 Inch SATA to USB 3.0 Tool Free External Hard Drive Enclosure [Optimized for SSD, Support UASP SATA III] Black (EC-UASP)

www.amazon.com

 

[ignatius345]

So It looks like the 128g blade SSD is gone. I'm not keen on taking the whole unit apart to replace it. Ideally I'd like to just run of the 2tb secondary drive for now and if I can get that working do the HD for SSD swap on that drive and just forget about the blade. Does this seem possible?

Same exact thing happened to my old 2014 iMac 5K. Turns out the way the Fusion Drive operates puts a LOT of read/write cycles onto the SSD, and because Apple skimped on the sizes of those they just wear out too fast. I caught mine (also a 128 GB blade SSD) when it was worn down to like 5% of its life according to DriveDx and another utility.

I ended up getting a kit from iFixit and opening up the iMac, replacing the SATA HD with a SATA SSD and leaving the blade drive in place. Sealed it up with the tape they provided and all was well. Since the 128 GB blade SSD was still operational I reformatted it and it would still mount on the desktop, though I didn't put anything on it after that.

If you're moderately mechanically inclined, patient and follow directions carefully it's honestly not that bad to open up. The worst part was carefully removing all the adhesive from the screen before putting on fresh adhesive strips. I'd guess the whole thing cost me about $250 total (including the 2TB SATA SSD I put in) and maybe 3 hours of my time.

There's also a very good thread here on the MacRumors forums somewhere about replacing the blade SSD on these machines. It's a little more involved and you have to source the drive very carefully to make it bootable, if I recall, but it gives you the fastest boot drive possible. The SATA solution was easier and fast enough for my needs, so I just left it at that.

 

[iOperate]

Thanks for the advice everyone. I'm trying to get loaded up off an external hard drive but having problems.

The SSD is dead and I cannot access it, erase it or do much of anything with it in disk utilities or terminal. It was running Monterey previously.

Now it appears I cannot use APFS. I tried loading Monterey on an external SSD formatted APFS and it cannot see the disk to startup from it or see it in disk utility. Trying to load Monterey onto the internal HD errors out about half way through, I'm guessing at the point that its converting it to APFS? External drive formatted as APFS will not show up in disk utilities or in the finder.

I can load El Capitan onto the spinning hard drive in OSX extended journaled and boot from it. I can format external drives as OS extended journaled and see them when I am booted into El Capitan.

Any ideas what is going on? Something about the dead SSD appears to be getting in the way of anything APFS related.

To reply to Fisherrman - when I'm booted into El Cap I can see the internal blade SSD in disk utilities. I cannot erase it - gives error cannot write the last block. I can run first aid and it completes showing an error - Problems were found that will prevent booting (or something like that).

I played around with terminal to try to split the fusion and any command I try that is related to APFS gives me no core services found or other null errors.

Thanks again

 

[iOperate]

Further to the above -

If the internal blade SSD needs to be removed before I can get things going again, does it have to be replaced? Or could I leave that slot empty and boot off my external? Or I could buy a blade and return the external ssd. The external runs off USB 3.0 so not sure the speed comparison between the two.

I suspect that whenever an apfs boot drive is attempted the SSD which is still alive but malfunctioning is hijacking the boot process and erroring everything out.

 

[Fishrrman]

OP:
"cannot erase it - gives error cannot write the last block. I can run first aid and it completes showing an error - Problems were found that will prevent booting (or something like that)."

OK, I'm going to guess that the internal SSD is busted, and you're not going to get it work again. So let's get on with other things.

Try this (to get the EXTERNAL SSD erased):

Power down -- ALL THE WAY OFF.

Press the power button and immediately hold down (and keep holding down):
Command-OPTION-R
This gets you booted to internet recovery (this is not the same as "the recovery partition").

You may need your wifi password, and the utilities will take a while to load.

When the utilities get loaded, open disk utility.

VERY IMPORTANT: go to the "view" menu and choose "Show all devices".

Now look at "the list on the left".
You should see the internal drives, AND you should also see the external SSD.

Click on the line that represents the physical external SSD (there may be listings for "volumes" on it, do not click on them, click on the line that represents the drive itself).

Now, click "erase".
Choose AFPS, and make sure it's GUID partition format.

Does it erase now?

If it does, quit disk utility.
Open the OS installer, and see if it will install onto the drive now.