I answer questions that have no answer because this question remains open in many forums. fully functional in MyCloud EX2 and MyCloud EX2 Ultra 2-bay NAS devices. I've tried JBOD, Spanning, RAID0, RAID1 and they all work as expected depending on the configuration chosen. For my final configuration, I personally use two WD RED 1TB SSD NAS in RAID0 for better performance and then use rotating USB disk backups for any failures/recoveries that may occur. I've also experimented with other brands of SSDs with no success. If you really need SSDs in your MyCloud EX2 or EX2 Ultra then I would recommend getting the official WD RED SSD NAS drives as these are the only SSDs I personally think will work.
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