There are also two different options for connecting more than one data server to more than one Windows computer. Again, the first option is available for QNX 4, QNX 6, and Linux. The second option uses QNX message passing over a network, which is only available for QNX 4 at present.
This option is essentially a multiple version of the Many to One option in the previous section. Here, each Cascade Connect on each Windows computer connects to one Connect Server on each data server.

Connecting more than one data server computer with more than one Windows computer can be accomplished using:
1 copy of the Connect Server on each data server for each Windows computer connected to it.
1 copy of Cascade Connect on each Windows computer for each data server it connects to.
1 copy of the Cascade DataHub on each data server is strongly recommended. (See When to use the Cascade DataHub.)
The scenario illustrated above would require nine Cascade Connect licenses and three Cascade DataHub licenses.
Connecting more than one data server computer running QNX 4 with more than one Windows computer can also be done by configuring one of the data servers with one Cascade DataHub and having the other data servers exchange their process data with the datahub using QNX message passing over the network. If, however, you are concerned about having a single point of failure in the system, you may want to consider the other option (above).

This connection can be accomplished using:
1 copy of the Connect Server for each Windows computer, all installed on one data server.
1 copy of Cascade Connect on each Windows computer.
1 copy of the Cascade DataHub also installed on that data server is recommended for unidirectional (read-only) mode, and strongly recommended for bidirectional (read/write) mode. (See When to use the Cascade DataHub.)
The scenario illustrated above would require three Cascade Connect licenses and one Cascade DataHub license.