Figure 24-2 shows an example of a consolidated server environment that is based on Linux. There are two mainframes: A and B. Mainframe A is an IBM zSeries 900 machine, in which z/VM runs in an LPAR.
z/VM is required to manage the three VM guests, one is used to run Linux for zSeries, a second is used to run Linux for S/390, and a third is used to run TCP/IP. The Linux for S/390 guest acts as a router for routing information between the internal network that connects the three z/VM guests and the external Ethernet LAN.
The Linux guests and TCP/IP guest are connected by means of virtual HiperSockets, ensuring fast and efficient communication among these guests.
The z/OS and Linux for zSeries that run in LPARs communicate with each other via a hardware HiperSockets function. They can also communicate with each of the Linux guests of Mainframe A through the OSA-Express adapter and the Linux for S/390 guest.
The OSA-Express adapter, which uses a high-speed I/O protocol called Queued Direct Input/Output (QDIO), enables communication to take place between the 1-Gigabit Ethernet LAN and the:
- Linux for zSeries operating system running in an LPAR of Mainframe A.
- z/OS operating system running in an LPAR of Mainframe A.
- Linux guests of Mainframe A, through the Linux for S/390 guest.
Mainframe B represents a technology that is slightly older than that of Mainframe A. It is either an IBM 9672 G5 or G6 computer, where z/VM runs in native mode.
z/VM manages the five VM guests, each of which is used to run a Linux for zSeries operating system.
The VM guests are connected by means of virtual CTC connectors.
The Linux guest called Linux for zSeries (3) acts as a router between the Gigabit Ethernet LAN and the Token-Ring network.
Any of Mainframe A's Linux systems, or Mainframe B's Linux systems, can communicate with the Token-Ring through Mainframe B's:
Linux for zSeries (3) router
This assumes, of course, that the routing table of the TCIP/IP guest in Mainframe A contains an appropriate routing entry.
In the "real world," however, companies might configure their mainframe to have a hundred or more Linux guests and LPARS, used for running a wide range of applications. Such configurations are considerably more complex than that shown in Figure 24-2.