>>It's not talked about NFS because it is not necessary.
Yes it is important. vRPA cluster need shared storage for repository. It even dont start installation without both ESXi-s see the same datastore (I tested it). Also, from documentation I readed it must be datastore and not shared virtual disk.
iSCSI I can let both ESXi initiator connect to the same iSCSI target, but vCenter dont allow me to mount datastore in this LUN in both ESXi simultaneously. When datastore is in one ESXi, then in other ESXi vCenter dont allow to mount the same datastore. There is even no option for that. Only option is to make new datastore and the window is empty for that iSCSI target.
>>>>RecoverPoint for VMs supports TCP/IP or iSCSI communication modes between the splitters and the vRPAs. IP splitter communication mode is preferred.
Splitter is vim and io-filter installed automaticallt into hypervisor while cluster install process. Communication must done between vmkernel adapter and vRPA vm (second virtual nic). Of course its TCP/IP, its virtual network. What iSCSI? What is iSCSI to do between vmkernel adapter and virtual machine virtual nic? But installer automatically installs this vRPA VM second virtual nic while install process. First after OVA installation, vRPA comes only with one virtual nic. I made this install process already successfully one time, but with only one vRPA node. Now I want to install 2 vRPA node cluster (that is recommended). But cluster installer even dont allow me to choose second ESXi. I have 2 ESXi, ESXI_12.40 and ESXi_12.42, where vRPA-s are installed. When I boot up vRPA in ESXI_12.40, open web management and start installing cluster, it shown in ESXi-s choice only ESXI_12.40. And ESXI_12.42 grayed out and error says "Incompatible VM VLAN configuration". When I boot up vRPA in ESXI_12.42, boot it up, start installing cluster, it shows I can choose only ESXI_12.42 and for ESXI_12.40 it shows "Incompatible VM VLAN configuration".