Hi,
Does these command help you?
::> storage pool show
::> storage pool show-disks [This shows you individual SSDs capacity]
::> storage pool show-available-capacity
If you want to know 'raw' physical size of the SSD, go to specific node.
::> node run -node node-0x
node-0x> sysconfig -r
You can see the physical raw size of the SSDs.
Thanks!