Resolved Is macOS incapable of seeing/using drives/storage over 16TB?

[ZombiePhysicist]

I just got a 22TB Seagate Exos drive for my 2019 Mac Pro. I've had 12, and 16TB models work just fine but needed a bigger one for time machine. It does not show up at all anywhere and it' just plugged into the SATA port.

Normally I would think maybe I got a bad DOA drive or something. But over in this thread, I have been hitting a roadblock getting larger 30TB SSDs working, and I'm starting to wonder, maybe macOS cannot see more than 16TB?

Is anyone successfully using (non RAID) single drives over 16TB successfully? If so, could you share the make/model of the drives that do work for you? And what version of macOS you’re using?

 

[HobeSoundDarryl]

I use a 20TB single HDD regularly with no issues but not with a Mac Pro. For the last few years, I've used multiple Seagate Exos X18 (18TB) drives in the same way. No issues with them either.

Drive format?

Try different bay?

Try bare drive dock to effectively make it an external drive for a test. Format it and verify it has full capacity. Then put it back into the internal slot and check capacity.

 

[ZombiePhysicist]

I use a 20TB single HDD regularly with no issues but not with a Mac Pro. For the last few years, I've used multiple Seagate Exos X18 (18TB) drives in the same way. No issues with them either.

Drive format?

Try different bay?

Try bare drive dock to effectively make it an external drive for a test. Format it and verify it has full capacity. Then put it back into the internal slot.

Thank you. Why the heck is this thing not coming up. So weird. Am going to try it on external dock.

 

[HobeSoundDarryl]

If none of that works and you have a PC, connect it and format it for PC (I suggest ExFAT format for cross platform compatibility with any helper apps).

Then bring it back to Mac, check capacity and try formatting it for macOS again. In my experience, PC seems more flexible at seeing and working with more drives... and generally offers low level formatting to revive the ability to use drives Mac can't see. Most of the trick is getting Mac to recognize full capacity, so the PC massage might reset something so that Mac can then see the drive in full.

 

[ZombiePhysicist]

OMG. DOA drive. Wont spin up.

I hate this case, it made diagnosing this a misery.

Thanks @HobeSoundDarryl

 

[ZombiePhysicist]

If none of that works and you have a PC, connect it and format it for PC (I suggest ExFAT format for cross platform compatibility with any helper apps).

Then bring it back to Mac, check capacity and try formatting it for macOS again. In my experience, PC seems more flexible at seeing and working with more drives... and generally offers low level formatting to revive the ability to use drives Mac can't see. Most of the trick is getting Mac to recognize full capacity, so the PC massage might reset something so that Mac can then see the drive in full.

Yea, I tried booting up in bootcamp, when it didnt show up there, I had bad feeling drive was bad. Thanks for the sanity check!

 

[HobeSoundDarryl]

Glad I could help. As in all things tech- even Apple things- occasionally we get a dud. Hopefully the swap for a working one is not too difficult. I generally find those drives work just fine and have been using some for a few years... including having some installed in an always-on, BIG NAS system.