Specifications

Chapter 15. Virtualization 159
It is possible to configure logical disk drives to be shared among multiple virtual guest
machines. Do not do this unless you are absolutely certain you know what you are doing!
Linux (which we assume is the basic operating system on all the virtual machines) does not
routinely support shared disks.
2
(To better understand the considerations, think about the disk
cache that is so important for Linux performance.)
15.1 VMWare
Again, we stress that you must obtain the necessary skills to install and use VMWare.
Figure 15-1 illustrates a basic VMWare configuration that was used for initial zPDT testing.
Figure 15-1 Simple VMWare configuration
In this configuration we have a VMWare server
3
with two virtual machines (Linux1 and
Linux2). The VMWare hipervisor has its own IP address (192.168.0.199). Each virtual guest
has an IP address for a (virtual) NIC. The console on the VMWare server is used for the most
basic hipervisor configuration (such as assigning an IP address); it is not used to manage
virtual machines that run on the server. In our most basic configuration, only a single NIC
existed on the server and was shared by VMWare and all guests.
4
2
Read-only (logical) disks might be used, but not if they contain emulated 3390 z/OS volumes. z/OS does not
support read-only volumes.
3
We initially used ESXi Essentials, but later changed to VSphere Enterprise on one of our test machines.
4
In later configurations we assigned a separate NIC to each Linux guest. Our 3650-M04 machines had at least four
NICs. With our test workloads the use of a single shared NIC presented no problems.
NIC
192.168.0.2
vCenter
client
NIC
192.168.0.3
VNC
viewer
NIC
192.168.0.4
x3270
x3270
NIC
Linux
License
server
UIM server
Datastore
192.168.0.198
NIC
VMware
hypervisor
192.168.0.60
Linux2
guest
vncserver
zPDT
192.168.0.50
Linux1
guest
vncserver
zPDT
192.168.0.199
VMware server
Console
Router/hub
Windows
Control
Point
Windows or Linux
Could be used to access
the Control Point remotely
Linux (or Windows with PCOM, etc.)
zPDT z/OS users
This could be a guest within
the VMware server