In the network shown above, RSTP will always disable one of the links, and any redundancy will be lost. Spanning tree's job is to determine one path, and one path only, to any given destination. Any redundant path's will be turned off by STP.
What you CAN do in this situation, and if you wish to split your traffic into two or more VLANs, you can run MSTP, and create an instance for each VLAN. For instance, you could split your traffic up into two VLANs, name them VLAN 200 and VLAN 300, and assign them to seperate SIDs (SID 2 and SID 3 respectively). Your command set would look something like this (this is from memory, btw):
The command for setting up MSTP for each instance are as follows:
switch(su)->set spantree stpmode iee8021 <---not needed on C/D/G Series
switch(su)->set spantree version mstp
switch(su)->set spantree mstcfgid cfgname MSTCFG-1
switch(su)->set spantree msti sid 2 create
switch(su)->set spantree mstmap 200 sid 2
switch(su)->set spantree msti sid 3 create
switch(su)->set spantree mstmap 300 sid 3
In order for the stations in each of these VLANs to communicate with each other, they will need a routed interface, so you'll have to set that up as well. If you want link redudnancy, you'll also want to set up different switches to be the root bridge for each instance. And although there are other ways to skin this cat, this will ensure that all traffic won't be restricted to just one link, enable the redundant links to share the load, and to ensure that a path will exist should one of the links fail.
Otherwise, you can simply enable RSTP and be content with the fact that one of your links will not be in use unless another fails. And as always, don't be afraid to call GTAC. They know what they're doing, and they are always ready to assist.
Good luck.
