SCO OpenServer System Release 5.0.7V 
          OpenServer 5 Definitive 

          I am seeing problems with the accuracy of the System Clock on
          my SCO OpenServer 5 Virtual Machine running on Microsoft
          Hyper-V, or other Hypervisor. Under light load, the drift in 
          accuracy is small but under heavy load the drift can be
          significant.

          What can I do to ensure that my system maintains accurate
          system time when running in a Virtual environment?

          It is highly recommended that SCO OpenServer 5.0.7V for 
          Hyper-V systems synchronize the system clock to an 
          external time source. This can also be helpful for virtual
          machines on other Virtual platforms, like VMware or Virtualbox.

          This can be done in one of the 2 following ways: 
           
          1. Using ntpdate(ADMN) 
           
          This method manually syncs to an external time keeping 
          source. The recommended method for doing this is to set up 
          a root cron job to manually sync periodically. For 
          example, the following line in root's cronfile will sync 
          to the external time server *clock.isc.org twice an hour: 
           
          25,55 * * * * /etc/ntpdate -v clock.isc.org >> 
          /var/log/ntp.log 2>&1 
           
          You may find that more frequent clock synchronizations are 
          desirable and choose to run this more often. You can see how 
          far the clock was off in seconds in the offset field in ntp.log.  
           
          * clock.isc.org is used for an example here only - though an
          open access public time server, its suitability to sync 
          your server's clock is not being advocated here. 
           
          2. Using ntpd(ADMN) 
           
          ntpd provides for automatic synchronization of your system 
          clock with one or more external time servers. ntpd 
          behavior is governed by its configuration file, 
          /etc/ntpd.conf. A basic /etc/ntpd.conf file syncing to a 
          single server might look like this 
           
          server clock.isc.org 
          broadcastclient no 
          driftfile /etc/ntp.drift 
          
          Check the ntpd(ADMN) manual page or the official ntpd documentation
          at http://www.eecis.udel.edu/~mills/ntp/html/index.html for more
          information on how to configure ntpd.
 
          **Important Note** 
          The following 2 problems have been noted with ntpd: 
           
          - Under heavy load ntpd may stop synchronizing the system 
          clock. This has been observed to rectify itself shortly 
          after the load on the system has subsided.  
           
          - Even when ntpd is successfully syncing the system clock, 
          it will log messages in /var/adm/syslog or your specified 
          ntp log stating "synchronisation lost" 
           
          These issues have been reported to SCO Engineering. If you 
          experience either of these problems then we recommend you
          consider using ntpdate(ADMN) instead. 

           Manual pages for ntpdate(ADMN) and ntpd(ADMN)

           http://www.eecis.udel.edu/~mills/ntp/html/index.html