Replacing 4TB for 12TB Red Pro in EX2 Ultra


Will it work to replace the 2x 4TB drives for 2x 12TB Red Pro HDD in my MyCloud EX2 Ultra?
I think I have read somewhere it is possible to replace them for 10TB drives?

Thanks Rudolf

Yes that works.

Hi - do you know if that will work on a My cloud ex ultra 2 that is 3 years old which was originally sold with a max disc size of 4TB / disk?

Yes the OS3 firmware supports any size of WD Red drives… they just don’t update the list of officially supported drives that often (at the bottom of


Thanks thats really useful.

So while I’m on can i ask how you might suggest I migrate from my existing 2GB RAID1 NAS configuration to a 10GB RAID1 NAS configuration.

Is it as easy as removing a 2GB RAID1 disc and replacing it in the bay with a new larger disc and allowing it to sync to the new device - then remove the other old device and replace it with the other new device and allowing it to sync again?

Or am i going to need to back it up somewhere and then set up the new RAID1 pair, copying the data back to the disc manually?

Thanks in advance


The price of 10TB vs 12TB isn’t that much of a difference, in case 12TB doesn’t work it’s way too much… :wink:
I don’t mind about officially supported, I just want to be sure it works

BTW, I’ve got EX2Ultra with 2x WD red 10TB (WD100EFAX-68) here myself, straight from the web shop… so it’s definitely supported.

Expanding RAID is indeed that simple, I suggest looking up the instructions in the support section.

I received an anwser of WD support this morning where I have asked the same question:

We have received your email about biggest capacity of the My Cloud EX2 Ultra NAS. Thank you for your interest in our products.

Currently the biggest capacity the EX2 Ultra exists is 20TB (2x10TB drives):

The link above also has a hard drive compatibility list for this device. Drives of 12TB (or higher) are not supported by the current processor of the device, regrettably.

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