OpenVMS x86-64 V9.2-1: Significant TOY Slippage over time

[bobgezelter]

I have observed multiple occurrences of accumulating TOY skew running OpenVMS x86-64 under Virtual Box. The underlying Windows host is not particularly busy. In the most recent episode, the time skew is over 1 hour 50 minutes(!) in approximately 24 hours. The skew appears not to be uniform, but episodic.

The hardware/software configuration is:

Host CPU: Dell Latitude E6420 (i5-2520M@2.5GHz; Turbo to 3.26GHz; Typical usage: 30% @ .90GHz); 16GB; 2TB Seagate Barracuda

Host OS: Windows 10 Professional, all patches to date
Virtual Machine: Oracle VirtualBox 7.0.6r1555176 (Qt5.15.2)
Basic OpenVMS x86-64 install; only VSI-supplied basic products (OVMS Community License; TCPIP; DECnet IV)

Examples:
Host Time (EDT) VMS Time (UTC)

Bootstrap 1:
09:38 1338Z
15:25 1857Z
16:26 1958Z
16:47 2019Z
18:46 2218Z
22:49 0219Z

Bootstrap 2:
10:25 1425Z
10:31 1431Z
23:22 0309Z
09:23 1211Z

This is a serious flaw for multiple reasons:
- The slippage is not at a constant ratio. Processes that sequence events based on time can not be reliably run if the clock reference is unpredictably varying. At best it triggers timeouts and correctable errors. At worst, it can compromise the safety of equipment operation.

- Time comparisons between OpenVMS-recorded events and other logs are not reliable.

- Unreliable time stamps compromise the ability to use OpenVMS log time stamps in legal proceedings. Having testified in court involving software-generated logs, unreliable Time of Year recording significantly undermines the reliability of such logs.

- SET TIME from DCL has no effect

It should be noted that guest Ubuntu LTS 20 virtual instances do not encounter corresponding difficulties.

- Bob Gezelter, http://www.rlgsc.com <gezelter@rlgsc.com>

[bobgezelter]

jonesd,

Yes, my VM host(s) is/are connected to the network. Running NTP is a possibility. HOWEVER, using NTP is far less efficient than a hypervisor call.

Second, and far more importantly, is whether the base OS TOY is reliable. Part of my consulting practice involves forensic and evidentiary issues. Log timestamp reliability is a significant issue in investigations AND when matters end up in some form of litigation. The base OS TOY should be reliable on a production system without special site-specific provisioning arrangements.

Been in the hot seat more than a few times. Take my word for it: Timestamps count and will be correlated against external events.

Note that to the best of my knowledge linux with the VirtualBox additions appears to do the correct thing.