Hi, It depends on the RAID level, but more than 8 should be fine. 16 virtual disks per disk group. So yes your example is fine. You cannot pause the raid expansion. 
Hello, I have poweredge r720xd with a perc h710 min embedded raid controller, 1. I remember that I read some where that the max number of drives I could have in a single virtual  disk in this server was 8 is this true? 2. how many different raid types can I have in the server at once, for example can I have 1 raid 0, 1 raid 5, and one raid 6? (a virtual disk for each raid) 3. if I am adding a drive to this array can I pause the raid expansion during work hours? thanks Regards Eric Hendrickson
poweredge r720xd raid limitations