Change and synchronize the time-of-day Clocks

z/VM® allows you to simulate running your sysplex environment with a date and time that is different from the system date and time with the CP SET VTOD command.

In a z/VM environment, all virtual machine Time-of-Day (TOD) clocks are synchronized with the system TOD clock when they log on. If you want to run the virtual machines in a sysplex with a TOD setting that is different from the current system TOD setting, you must change and synchronize all the virtual machine TOD clocks within the sysplex.

To change the TOD clocks for the coupled guests, prior to starting your sysplex issue the following sequence of commands:

From the CGUEST1 user ID, issue the DEFINE MSGPROC commands to add CFCC1 and CFCC2 to your I/O configuration. Because CGUEST1 has only Class G privileges, the SET VTOD command in the next step requires that the CF Service Machine whose date and time that you want to set be in the I/O configuration of the coupled guest that is issuing the SET VTOD command.
```
def msgp cfcc1 vdev 400
```
```
def msgp cfcc2 vdev 500
```
From the CGUEST1 user ID, issue the following commands, substituting the appropriate values for the date and time.
Set the TOD clock:
```
set vtod date mm/dd/yyyy time hh:mm:ss
```
Set the TOD clocks for the CF Service Machines:
```
set vtod cfcc1
```
```
set vtod cfcc2
```
Issue the following command from the CGUEST2 user ID to synchronize the CGUEST2 TOD clock with the sysplex:
```
set vtod fromuser cfcc1
```
Issue the following command from the CGUEST3 user ID to synchronize the CGUEST3 TOD clock with the sysplex:
```
set vtod fromuser cfcc1
```

See z/VM: CP Commands and Utilities Reference for a complete description of these commands.