Hi,
It should be ok.
I checked the Hardware Universe and it shows supported speed 6/12Gb (i.e when connected both will operate a lower common speed as negotiated by the controller ). Attached pdf for E2724 Adapter cards.
For HP H221, we are supposed to check Interoperability matrix (https://mysupport.netapp.com/matrix) : I checked this as well, here you need to check it against the E2724 OS Santricity (I don't know what you are running) but it shows supported for most Controller OS. You can also verify once using the links below, it also suggests which driver/firmware update is needed, which is very useful for proper communication.
Hardware Univserse:
https://hwu.netapp.com/
Interoperability Matrix:
https://mysupport.netapp.com/matrix
Thanks!
