Can I insert an SSD into WD My Cloud EX2?
Sure if you have the correct form factor. You will likely need a caddy:
Beyond just inserting a random set of SSDs which may or may not work, be sure to use the official WD Red SSD NAS drives:
I have used and tested sets of these in both a MyCloud EX2 and MyCloud EX2 Ultra dual-bay NAS and they work great for JBOD, Spanning, RAID0, and RAID1 configurations. I tried some other branded SSDs (e.g. Kingston) and they did not work in the EX2 series NAS.
I’ve used the Sabrent mount before and agree it is a good choice in general, but for the EX2 style NAS slots I use something a little more chunky that is roughly the dimensions of a 3.5" drive: