Manual

HP NonStop Time Synchronization User’s Guide Page 17 of 81
To eliminate potential issues with the system clock being set backward, TimeSync can
instead be configured to “drift” backward changes in slowly as well. In this case, TimeSync
never alters the system clock to an earlier time. Instead, it works by slowing down how
quickly time moves forward on the system, essentially waiting for the reference source to
“catch up” before resuming normal timekeeping. This does not, however, mean that time
stops on the local system. Instead, it moves forward slightly more slowly than real time
until the clocks are synchronized.
Options to control how TimeSync updates the local system time can be set in the
TimeSync configuration file, or via the TimeCom CI. See Configuring TimeSync for more
information on how to set TimeSync up for your particular environment.
1.3. NonStop TimeSync Architecture
NonStop TimeSync consists of three components: the TimeSync process itself adjusts the
local system time if client mode is enabled and/or provides reference times to other
sources if server mode is enabled; the TimeSync configuration file contains settings to
control the TimeSync process; and the TimeCom command interpreter provides a user
interface to dynamically query and update TimeSync process settings.
There are four versions of NonStop TimeSync:
 TimeSync for NonStop (T0811) provides time synchronization for HP NonStop servers
running G06.00 or later, HP Integrity NonStop servers running H06.00 or later, and HP
Integrity NonStop BladeSystem servers running J06.00 or later. It consists of two
versions of TimeSync, one that executes in the Guardian environment and one that
executes in the Open System Services (OSS) environment. You can use either version,
depending on your preferences for your particular system.
 TimeSync for Linux (T0812) provides time synchronization for Linux servers running
RedHat Enterprise Linux 3.0 or later, or Suse Linux 9.0 or later.
 TimeSync for Windows (T0813) provides time synchronization for Windows systems
running Windows XP, Windows 2003 Server, and Windows Vista or later.
TimeSync capabilities are largely equivalent between platforms. In all cases it has the
ability to run both as a client (wherein it adjusts local system time based on reference
times received from other sources) and as a server (in which case it supplies reference
times to other clients). The product components are also the same on each platform, and
consist of the TimeSync process itself, the TimeCom command interpreter, and the
TimeSync configuration file. Unless otherwise stated, any reference to a TimeSync
capability, feature, option, or command in this document applies to all platforms.