Hi
Protection level is disk space left for sparing that will not appear in your total capacity.
this capacity is always from the largest disk size that is single protection means you lose 2 disks (2 X450 GB)
of the largest size and double means you loose 4 disks.
raid is the way data is spread on the disks if you have raid 5 you loose 20 % and raid 6 40 %
and you can be sfe if 2 disks fail
RSS is an internal setting that the EVA sets. it tries to group the disks into groups of 8 (1 RSS) if
it can but it can go down to six disks and up to 12 disks. you will probably have 2 RSS.
Regards
if this helps give KUDO