1 Description
2 Step-by-step guide
- 2.1 Configuration file settings
- 2.2 Virtual machine operating system settings
  - 2.2.1 On OpenVMS/AXP
    - 2.2.1.1 Using a batch queue
    - 2.2.1.2 Using a detached process
    - 2.2.1.3 Considerations using DECnet-Plus software
  - 2.2.2 On Tru64 UNIX
3 Related articles

Description

This document will explain how to implement the time synchronization feature using the "sync_to_host" parameter in the configuration file. This parameter allows to keep TOY time always synchronized with the host's time and disable undesirable updates to the TOY from guest OS.

Restrictions: Minimum product versions/builds required:

Windows:
- Charon-AXP V4.4 Build 148-02 with patch 148-09 installed
- Charon-AXP V4.6 Build 166-03 and later
- Note: Charon-AXP V4.5 Build 153-03 and 153-05 (patched) are not supported
Linux:
- Charon-AXP V4.6 Build 168-03 and later

Step-by-step guide

Configuration file settings

Update the configuration file with the following settings:

Syntax:

set TOY sync_to_host = "{as_vms | as_tru64 | as_is}[, nowrite]"

If "sync_to_host" parameter is specified there is no need to specify "container" parameter in addition.

where:

Parameter	Description

Parameter	Description
as_vms	If the guest OS is OpenVMS/AXP and its date and time must be set to the host's date and time each time it boots.
as_tru64	If the guest OS is Tru64 UNIX and its date and time must be set to the host's date and time each time it boots.
as_is	If the TOY date and time must be set to the host's UTC date and time
nowrite	Forbid updates to the TOY from the guest OS If you want guest to synchronize itself using DTSS or NTP for example, remove "nowrite"

Example:

set TOY sync_to_host = "as_vms, nowrite"

To synchronize the guest OS with TOY, use the following commands (from "SYSTEM"/"root" account):

On OpenVMS/AXP	On Tru64 UNIX

On OpenVMS/AXP	On Tru64 UNIX
`$ set time`	# date -u `consvar -g date \| cut -f 3 -d ' '`

The default value is "not specified" - it means that by default Charon does not synchronize its guest OS time with the Charon host time but collects date and time from the file specified with "container" parameter.

If "sync_to_host" parameter is specified there is no need to specify "container" parameter in addition. If both parameters are specified, only the seconds of the guest system time are synchronized with the host time.

The Charon virtual machine must be restarted in order to take the new parameter into account

Virtual machine operating system settings

The commands mentioned above used to synchronize the guest OS with TOY are effective only when they are executed. To avoid time difference, these commands must be executed at specified intervals.

You will find below examples on how to implement scripts to perform time synchronization for OpenVMS and Tru64 UNIX.

If you have NTP running on your OpenVMS or Tru64 UNIX system, you can keep it running even if sync_to_host is enabled

On OpenVMS/AXP

You need first to perform a manual synchronization between the Charon server and the Charon virtual machine using the SET TIME= command:

$ SET TIME=12:30:00

You can use either a batch queue or a detached process to synchronize time. The two methods are described below.

Using a batch queue

Create a simple script containing the following lines. The example below will sync time every hour:

In our example, we will create the script in the SYS$MANAGER folder and name it CHARON_SYNCTIME.COM. The OS version used is OpenVMS 7.3-2. Its content is:

$ SET NOON
$ SET VERIFY
$LOOP:
$ SHOW TIME
$ SET TIME
$ SHOW TIME
$ WAIT 01:00:00
$ GOTO LOOP

How to implement time synchronisation between CHARON-AXP Host OS and Guest OS (sync_to_host)

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