thanks you for the response but it looks like I'm the problem ;) It's actually a 2 step process to get this working. 1 -  System setup (f2) --> device settings --> h710 management --> VD Management --> Reconfigure VD --> Selected Raid 5 -->  Select new disk --> click apply. then, the screen goes back to the previous menu 2 - Make sure Raid 5 is still selected, click apply again voila...
H710 mini installed on a R320 server. 3 Sata drives in a RAID5 group, 1 VD 1 Sata drive not configured All drives the same make, and model, I'm trying to add the 4th disk and expand the VD but the Expand VD size option is greyed out. Installing OMSA is not an option on the server. What am I missing here?
Cannot reconfigure RAID5, Expand VD size option greyed out on H710 mini