Synchronize engines and servers

The times on the engine and server machines must be synchronized. By default, DCM allows machines accessing the same database to have time discrepancies of up to 60 seconds. If a machine has a time difference that is greater than 60 seconds with another machine, the object might not be included in DCM transfer packages.

The DCM time sync tolerance can be modified to allow for greater time discrepancies. However, it is better to use standard time synchronization facilities of your operating system, such as using NTP servers, to keep system times synchronized across Synergy servers and engine hosts. DCM detects and reports an error during DCM receive for packages that appear to have been generated at some future time.

Here is a description of how object can be missed by a DCM transfer when machines are not closely synchronized:
  1. A DCM generate is performed on a server whose time is accurate.
  2. A few seconds later, a user checks in a file using a session with an engine process. The engine process is running on a machine that is 100 seconds behind the actual time. The object is not included in the first DCM transfer package because it was not checked in at the time that generate determined the delta.
  3. A few seconds later, another DCM generate is performed on the machine that has the accurate time.

    However, the object is also not included in the second DCM transfer package because it is older than the last generate time.

When a DCM generate is performed, DCM subtracts a small time value from the current time (by default, 60 seconds) to use as the generate time. This operation allows for a time difference of 60 seconds between machines accessing the same database. An object that is modified or becomes a direct or indirect member of a transfer set within 60 seconds of the start of a DCM generate can be included in that DCM transfer package and in the next one.

The synchronization process varies from one installation to another. For specific information about this operation, contact your system administrator.


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