Is there a size limit for attaching USB drives to myCloud?

I was hoping to use 3TB harddrives that are powered and connected via a SATA-USB3 connection. The drives are good- but when I connect to back of myCould it does a lot of thinking and then the red light comes on.

Red light goes away with removal.

Is it a size thing? Or does it not like internal HD that are connected via adapter?

Other USB drives including a 2TB mypassport- work fine.


What file format are they formatted with?

What is their 5V supply requirement (not that I know the limit of what the MyCloud can supply…)

NTFS -they have their own power supply; so should be good there.

There isn’t a size limitation for USB drives. The issue is probably with the SATA/USB dock-adapter you are using. The My Cloud may not be detecting properly since drivers cannot be automatically installed like on a computer.

Fascinating. That makes sense. Bummer.

Ihave a usb3 adapter vith 4 usb3 ports. I have a 8tb extern usb3 hd connected to each port so my extra space to my 4tb mycloud Nas are 32TB. this means that I have proximately 36tb space on y NAS.

What generation My Cloud do you have and have you looked at the User Manual for how and what you can connect to the USB port?

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No its not a size thing. More likely either a problem with the USB device itself or possibly how the drive is partitioned and formatted. The My Cloud seems to have issues if a USB drive contains more than one partition and the data partition isn’t the first partition. Often a repartition so the data partition is either the only partition or the first partition may solve that particular issue.

Where are you getting the red LED? On the front of the My Cloud? Or on the USB enclosure?

The only official limitation is the number of USB devices one can attach to the My Cloud. Currently the User Manual indicates seven total devices but as some of us have found attaching more than five USB devices may lead to mounting problems with the My Cloud. There are several past discussions on attaching multiple USB drives that can be found using the forum search feature, magnifying glass icon upper right.

As a data point I have connected a 5TB USB drive to the My Cloud without issue (use it as a Safepoint backup location).

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The red LED will appear on the front of the myCloud.

The drives came out of a busted synology NAS - but I put them back into a PC and formatted them to NTFS before bringing them back out and trying to attach to the myCloud

But your 8TB drive is an external drive correct? Not an internal drive that is connected through an adapter (SATA-USB3) - correct?
Otherwise, if you are using an adapter let me know which kind.

What is the make/model of the USB adapter the drive(s) are connected or attached to?

Stupid question but did you by chance not repartition the drives after they were pulled from the Synology NAS? Might have to use GPT for the partition type if it isn’t set to GPT already.

it is not an adapter, but a usb3 hub.
the hub is a star tech powered usb3 (But you can use any POWERED usb3 hub) connected to the usb3 port of the my cloud nas. the 8tb drive is an external powered hd formatted as ntfs :WD My Book (NEW) WDBBGB0080HBK - Ekstern Harddisk - 8 TB - Sort

So just to clarify. When you attach the WD My Book drive direct to the My Cloud without using the USB hub the My Cloud front LED turns red. Is this correct?

If you use the forum search feature, magnifying glass icon upper right, and search for My Book you’ll see a few others had trouble (or issues) using a My Book drive with the My Cloud. It is possible one of those past discussions may have additional helpful information.

If you’re relying to Jorn, I think his USB drives are working fine via his hub. He was just clarifying that he’s not using a SATA to USB adaptor, unlike the OP who is having problems…

OK - thanks to all who have weighed in so far. I think it is indeed the actual drive - I got a 2TB 3.5 inch drive connected using the same adapter (made by uGreen) and its just fine. So I’m going to try and reformat this drive (the long wipe) and see what happens.

The magic number is 4TB. Its CPU limited for MyCloud EX2 Ultra. It will initially detect drives larger than 4 TB but the OS5 will gradually freeze and stop responding until a power cycle/hard reset is done and then it will freeze again. Drives with 4TB or smaller works without any issues.

Probably not an issue with a more recent, more reliable USB HDD enclosure.

That being said, most myCloud devices are running on 32-bit Linux, therefore it is likely to be 16TB hard limit for a single partition. You may be able to get away with larger drives with split partitions but your mileage may vary.