Erase all data from a failed Fusion Drive

[Ankaa]

My trusty 27" iMac died last year and has been sitting since then for me to find the time to deal with it. Since it still powers on (and can boot from an external drive just fine), just can't boot from the fusion drive, I suspect it's the fusion drive that failed. Initially, I had hoped I'd still be able to safe my data off the HD portion, but upon repeated research, this seems to be neigh impossible. I'd even considered removing the drive before doing anything with the iMac itself (recycle?), but that of course is not straight forward with an iMac.

We now have a move in our near future and I'm wanting to put up the iMac for sale for parts or for someone to boot from an external drive. However, for obvious reasons I want to make sure all personal data was erased from the HD. In the disk utility, both drive portions still show up (but can't be mounted nor accessed). First aid and recovery failed and I'm reluctant to start "erase" in case it also doesn't work (or only partly) but then completely removes the drives from the disk utility. Since I can't access them, there's also no way for me to verify any data was actually indeed erased.

Any help or tips or pointers towards software tools that would help me with that are appreciated. Thank you.

 

[HobeSoundDarryl]

Not 100% sure, but I think the only way is to open it up and remove the drive entirely. But if you are going to do that- or have a shop do it for you- might as well replace the drive with maybe an SSD and thus have a working 27" iMac again that boots from internal drive. Shops will do this for you for not that much money, particularly authorized but not-actually-Apple shops. Bring your own SSD vs. buy from them to save some money. If you want to do this, the shop can install macOS on the new internal and then you could optionally "migrate" (migration assistant) from the external to the internal if you want to resume using it... or just leave it as a macOS (only) iMac for the sale.

You have to be able to access a drive to wipe it. An older remedy when it was only HDDs was drill some holes in the drive to basically destroy the platters. That probably works with fusion too. Maybe drill some holes, throw it in a bucket of water and leave it to soak/rust for a few months. That should even damage the SSD portion, supporting chips, etc.

 

[Ankaa]

Dang, I had hoped I could avoid having to open up the iMac. I actually have a repair kit here already, since last year I did want to just remove the drive (to deal with it later), but never ended up having the time nor necessary state of mind. Opening up an iMac is a hassle. But sounds like it might be my only option.

 

[HobeSoundDarryl]

I think it is if you want confidence about "no data recovery" from the internal drive. Someone else may chime in with some other option but if you have no software access to it, I think you have no options but physically removing it.

Again, if you go in, consider replacing the drive with an SSD drive. 1-2TB SSDs are priced $100 and lower. You'll very likely have a fully functional iMac again to use or (more easily) sell (as a functional Mac instead of "for parts"). ALSO, if you have any niche Windows needs and are going Silicon, you have a full Windows computer there too instead of only Windows emulation on Silicon. A very good use for an aging Intel Mac is to turn it into a "new" (or near new) full Windows PC if you have such needs.

 

[Ankaa]

Great point about keeping the Intel iMac for Windows, I didn't think that far! I admittedly haven't used Bootcamp in ages and resorted to Parallels for my odd Windows need every blue moon. It's definitely something to consider, though at this point I'm not sure if the iMac won't just start failing in other parts or becoming too slow/old. It's a 2015 one. It's a shame, though, because I'd really love to hold onto that 27" retina display... (I'm the demographic who's desperately been holding out for Apple to release a 27" iMac again...)

 

[HobeSoundDarryl]

OK, option 2: you can gut it while in there anyway and turn it into a 5K monitor for a silicon Mac...

Don't let the headline throw you. He PURCHASED an iMac 27". You already have one.

 

[Ankaa]

I actually looked into that last year, but came to the conclusion that I just wasn't convinced by the time, effort, and money that would have to go into it. It's tempting, very much so, but I really don't have the time to deal with that and taking it in somewhere for someone else to do it for me would just end up costing $$$ (instead of gaining some when selling)

 

[Fishrrman]

OP:

What happens if
You boot externally and open disk utility
then
Click on either the internal SSD portion (of the fusion drive) or the HDD portion
then
Click the "erase" button?

What do you see?
Do you have the option to erase it?
(you can still cancel out at this point if you wish).
Take a screenshot or phone pic and post it here so we can see what you see.

The way I see it, you have 3 possible choices:
1. Try to "re-fuse" the drives together (if they are "un-fused"). If the drives are not "physically broken/failed", you might just be able to "revive the fusion drive"...
or
2. Erase the drives,
or
3. Open the iMac and PHYSICALLY remove them.

If you erase one of them first, the other one should still "show up" in disk utility and allow you to erase it, too.

There is a "secure erase" feature in disk utility (though I never used it much).
A "one-pass" of random ones/zeros (or however it goes) should be "enough".

 

[Ankaa]

Since I posted, I also made one last attempt to recover some of the data with the Stellar Software following this thread. I've been running the demo version to see if it even is worth spending the $100. It does seem to find data, but I haven't gotten to the actual "recovery" part, yet. However, ever since I've done the scan, it changed the naming of the two internal hard drives. Before they were named something along the lines of "Macintosh HD" and "Macintosh HD - Data". This is what I see now in disk utility, as well as in the Stellar Software.

1. Try to "re-fuse" the drives together (if they are "un-fused"). If the drives are not "physically broken/failed", you might just be able to "revive the fusion drive"...

How would I do that? As far as I understand from everything I researched last year, it's the SSD part that just failed, but because it's a Fusion Drive, the HDD part cannot easily be accessed without the SSD running. I don't think it's possible to "restore"? But I don't know enough about this.

 

[DeltaMac]

Just to make this clear: The fusion drive is not a single device, and it is not a single drive that has two (or more) separate drives. It is a normal 3.5-inch SATA HDD (a spinning hard drive), PLUS a second device (the SSD) which is plugged in to a card socket on the backside of the main logic board. The two separate devices are combined through software, and appears to the system as one storage drive (at least, when the fusion drive is properly fused/working) The logic board has to be removed to pull that PCIe SSD, which is installed in a slot on the backside of that logic board.
One (or both) storage devices need to be pulled, if you really want to make sure that files/data are gone from both devices, or there are sensitive files that you need to "go the extra mile" to be certain of erasure.

 

[HobeSoundDarryl]

I don't know where you are but about $100 would be enough here in Florida to get a local (not Apple) shop to open an iMac and remove the drive. Then you can absolutely and thoroughly destroy it for complete peace of mind. You might want to check a few shops to see what they would charge.

And again, if you have a spare SSD around, perhaps have them slug it in and you'll likely have a functional iMac again that will likely sell for better than a "for parts" price... possibly enough to wash the service cost.

 

[Ankaa]

And again, if you have a spare SSD around, perhaps have them slug it in and you'll likely have a functional iMac again

Would I be able to use the external SSD I currently use to boot from? Or does it have to be a specific type of SSD? I also read somewhere that I would actually need to update the internal temperature sensor?

 

[HobeSoundDarryl]

I don't know for sure. I've been out of iMac for a long time now. If the temp sensor need applies, I'd check OWC or iFixit as they usually offer hardware workaround options when Apple tried to lock such things down.

Assuming the SSD would fit where the Fusion Drive would be removed, I would expect it to go right in. Again, OWC (macsales) or iFixit typically has upgrade tutorials for iMacs. Maybe check the one that matches your specific iMac to see what works? If their tutorial uses a SSD the same as what you have, I'd feel confidence in being able to swap it IN there.

 

[Mr_Brightside_@]

I can pretty much guarantee your external SSD won’t work inside the Mac, unless it happens to be an SSD that was pulled from a Mac and placed in OWC’s enclosure.
I personally once got very lucky in recovering data off a failing Fusion Drive for a client, and keeping the two drives together was key for this. I mention this because somebody local may be willing to remove the drives while you wait in exchange for the computer plus cash.
That said, the iMac isn’t as intimidating to open as it’s made out to be, provided you have the right pizza cutter. The most annoying part is getting at the SSD.
On the off chance you’re in the GTA, I’d be happy to help with some or all of this.

 

[Fishrrman]

Question:
How much do you want to spend on this old iMac?

Answer that first.
Then, we can go forward.

My advice:
ERASE the drives.
Try erasing both internal drives that we see in the first pic in your reply 9 above.

 

[Ankaa]

I can pretty much guarantee your external SSD won’t work inside the Mac, unless it happens to be an SSD that was pulled from a Mac and placed in OWC’s enclosure.

That's what I figured. No, it's not.

On the off chance you’re in the GTA, I’d be happy to help with some or all of this.

Unfortunately I'm in CNY, but thank you for the offer.

Question:
How much do you want to spend on this old iMac?

I do not actually want to spend any money on this old iMac; I had been planning to merely sell it for parts for someone who loves to tinker. This is after all a still fully functional and perfect 5k panel, that alone should be worth some bucks?. All I really care about is not giving anyone access to any sensitive data that was on the internal drive.

I don't have time or nerves to spend a lot of time with this iMac (as much as I'd like to, I like a solid project and am not actually afraid of doing it). If I'd had that it wouldn't have been sitting collecting dusk for now almost 2 years.

My advice:
ERASE the drives.
Try erasing both internal drives that we see in the first pic in your reply 9 above.

I think I may have blown my chance for that. While booted from the external drive yesterday and being in standby, the iMac just randomly crashed, restarted and unsuccessfully tried to boot from the internal drive. The drives now no longer show up in disk utility. Guess I will have to open up the iMac and pull the drive, just for peace of mind.