Why VLAN is no option for you? Your scenerio is a good usage model of VLAN. Actually I believe the only way to seperate one port from other on the switch is to use VLAN.
The configuration on this My Flex is the following, I have four Compute Module and one LAG with eight members, they are connectet to the system-switch. The big problem is, one of this Compute Module is a SQL-Server and the performance over the LAG is to slow (all Compute Module are active). I have tested the performance only with the SQL-Server (all other Compute Module are not active). The SQL-Server performance was much better.
I have see the Switch AXXSW1GB can make Trunk Groups, is this a option?
If I understand correctly, you're saying your SQL server is not getting enough bandwidth right? If that's the case you may want to configure QoS on the switch. See Ethernet Switch user guide, section 10 for details.