SVP time

BS2000 considers SVP to possess its own clock, which can be polled by the operating system via the privileged Store Real Clock interface. The SVP clock must always run in local time. Store Real Clock provides the SVP time with a resolution in seconds. The supplementary information provided by Store Real Clock depends on the architecture of the Server Unit:

• Time zone

• Display: synchronized with external timer

Server Unit	Supplementary information
SU /390	Time zone, Display: Synchronization by the MU active / failed MU synchronized with external timer
SU x86	Time zone, Display: MU synchronized with external timer

Depending on the architecture of the Server Unit, this clock may be present as a hardware clock or may be emulated by X2000, but in both cases it runs independently of the TODR.

Server Unit	SVP clock integration mode
SU /390	Autonomous SVP clock exists, synchronized by the MU. The MU can be synchronized with an external time or with other systems by means of NTP.
SU x86	SVP clock is emulated by X2000 with the help of the carrier system time. The carrier system time is synchronized by the Management Unit.

Notes for use under VM2000

On SU /390 the “Store Real Clock” of a guest system is emulated by the Hypervisor under VM2000. The monitor system’s system time is generally used to achieve this. The following exceptions exist which result in a Store Real Clock command being issued:

• The monitor system was started using a time entered explicitly by the operator.

• The monitor system is part of an XCS network.

• The monitor system is part of an NTP network which has not be configured with an external timer.

• The monitor system cannot be reached at the time the command is executed (e.g. when the monitor system is restarted).

On SU x86 the “Store Real Clock” is also emulated under VM2000 like a native of X2000.