OSF DCE Administration Guide--Core Components

Managing the DCE DST

Figure 25-2. Local Fault

Time

Intersection of

correct intervals

(computed time)

UTC

If DTS detects a faulty system clock during synchronization, the severity of the fault and

the system’s tolerance attribute setting determine how DTS reacts. When the fault is

detected, DTS performs one of the following operations:

• If the faulty time interval that is supplied by the clock is within the bounds of the

error tolerance, DTS increases the inaccuracy of the value supplied by the clock and

adjusts the clock gradually.

• If the faulty time interval that is supplied by the clock is outside the bounds of the

error tolerance, DTS immediately sets the clock to the new computed time.

Before you change the default tolerance setting (5 minutes), determine the requirements

of the applications that use the system time. Some distributed applications, such as the

CDS server, require that systems have no more than 5 minutes of inaccuracy. Larger

error tolerances may prevent such applications from properly sequencing CDS

namespace entries. For these applications, you will want to set the tolerance attribute

value to 5 minutes or less.

Some applications may require DTS to adjust the system clock gradually and

monotonically (forward). You can increase the tolerance attribute setting for these

applications to ensure that the clock is abruptly set only in the event of a catastrophic

error. If you could set the tolerance attribute value to inﬁnity, you could guarantee that

the clock is never set abruptly. This setting is not available, but you can enter any

setting less than 10675199-00:00:00.000 (approximately 29,227.5 years).

The following example shows how to set the tolerance attribute value to 3 minutes:

dcecp> dts modify -change {tolerance 00-00:03:00.000}

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