How to erase fusion drive with target mode?

[cltd]

Hello,
I have iMac (with dead GPU) which I want to get rid of, so I need to wipe out all data. Fusion drive still works, so I can reach drive with target mode.
I found a lot of threads how to split fusion drive, erase and then create it again. However, terminal-way works only when I can boot from this machine. But I can't, recovery mode doesn't work too.
So question is: how can I securely wipe fusion drive in target mode? Is it possible?

 

[barbu]

Do you know if the drive protected by FileVault? If so, you needn’t do anything since the data is already scrambled/random. If not, and the machine still runs, you could enable it. This would be the fastest way. Otherwise you could use a tool that would overwrite the disk with random junk a few times. This takes a while though.

 

[cltd]

Thanks for advice. Apple Disk Utility doesn't work with technology Apple sells... such downer.
Perhaps I'll try this software:

Securely and Permanently Wipe Data from Fusion Drive on Mac

Learn how to erase Fusion drive on Mac. Start your iMac/Mac Pro or MacBook into Recovery mode, and then choose Disk Utility, use it to erase the Fusion drive on your Mac.

www.doyourdata.com

 

[cltd]

Do you know if the drive protected by FileVault? If so, you needn’t do anything since the data is already scrambled/random.

barbu, I can boot iMac drive from Macbook via target mode. If I get into iMac OS and switch Filevault on, will it secure my data?

 

[barbu]

Essentially, yes. Encrypting the data and discarding the key (your password) is functionally the same as overwriting the disk with random data. From a file recovery perspective, there is no difference. Bonus points if you set it up with a password that even you don’t know

 

[Fishrrman]

What I'd try:
a. boot to target disk mode
b. open disk utility
c. select the fusion drive
d. ERASE it, "as is"
e. once "the first erase" has gone through, turn on filevault for that drive (not sure if this can be done, I don't use filevault)
f. once the entire fusion drive has been encrypted via filevault, RE-open disk utility
g. now, ERASE the encrypted drive AGAIN
h. at this point, I'm guessing that for all practical purposes your data is "un-recoverable"...

 

[barbu]

those steps are fine but I think qualify as "security theatre". A scrambled drive is indistinguishable from an encrypted drive. As long as OP keeps the password to themselves, or never memorize it in the first place, the data is unrecoverable. It will be random junk to anyone looking at it. The outcome is the same but with fewer steps.

 

[cltd]

Bonus points if you set it up with a password that even you don’t know

Hey, it's a part of the plan

c. select the fusion drive
d. ERASE it, "as is"

If I've understood forums, that's the problem - Disk Utility will not let me erase fusion drive.