Just to be sure, the KBA at My Cloud RAID Online User Guide and Solutions implies that if one needs to swap drives in a RAID configuration, the replacement drive must be the same size. That is, is a 4TB HDD is removed it must be replaced with a 4TB unit. In other words, there’s no way I can replace a 4TB HDD with a 6/8/12TB HDD.
NO idea if this will work with WD ex but a backup copy many be faster
Used other NON WD NAS to do the following
Upgrading RAID 5 array with a larger hard disks
Backup everything, blow away the raid array and restore to the new array. ( Faster)
Replace 1 drive wait for it to finish rebuilding. Continue one at a time waiting for rebuild to finish.
Once all drives have been replaced most raid controllers will then let you expand the raid volume it’s self.
Option 1 sounds good but unfortunately the WD NAS is my backup and I don’t have 12TB of space anywhere else.
I set my raid to use a few shares so I can backup using the USB port to smaller disk units
no need to have to backup raid to ONE disk. You can still put more than one share on a backup USB port disk.
The MyBook 4 TB have been on sale and I have a lot of old WD 1 and 2 TB internal drive from old system people gave me after updating their systems.
The SATA to USB-3 interface is easy to find and is even a part inside old MyBook units that people throw away.