Drive installation failure

My installation of a new drive in the EX4 failed. I suspected the drive and have since received a replacement from WD but I haven’t tried to install it suspecting that it’s not the drive but EX4 software. I’m running OS X 10.11.8 El Capitan and the EX4 is current with 2.11.157.

I sent an inquiry about this to WD Support and the response was that the installation process should work even if the new drive was a different capacity.

I have three JBOD 1TB drives and a vacant slot. I shut down the EX4, installed a new 3TB WD NAS drive in the fourth slot, powered up, waited for the fourth LED to become red and opened Dashboard.

In Storage/Disk Status the fourth drive was shown as Good. Selected Storage/RAID/Change RAID Mode/Select JBOD/check Create New Volume(s)/Next/ The Change RAID Mode box is displayed and Drive4 3TB is displayed and a “Drice Self Test” runs with a “Good” outcome.

An encryption option displays and selecting Next (without encryption) displays a summary of the selected configuration and selecting Next displays a pre-format notice and selecting Finish displays a Partitioning notice and a Formatting progress bar.

The Formatting progress bar remains 0 and in about 12 minutes a format failure message is shown, “Error Code 635.”

About a year ago I swapped out the first three drives and had no trouble at all. Am I missing a step or making an error this time? Any suggestions? Thanks

The process in question follows the right steps. Is this happening only with this particular new drive in said slot? If you are building a new volume, does it proceed with an already functional/tested drive swapped into the previously-empty slot? If it succeeds then the new hard drive is at fault even if it passes the test. If it fails then the unit’s controller has a problem in said slot and the WD My Cloud EX4 itself should be replaced.

Thank you. Moving a functioning drive from another slot into the fourth slot works OK. I placed the new drive into the third slot and it did partition/format successfully and then created a share and moved it into the fourth slot and it seems to be OK. I will ask support if the partition/format failure in the fourth slot a EX4 fault.