TSD Time Calculations


Overview

Tasks

Included with

Tivoli Service Desk

Overview

TSD time processing

Tivoli Service Desk incorporates several functions that standardize the way time is stored in the database and make time data easier to understand.

Displayed time data

When users view time-sensitive data stored in the TSD database, time appears in the context of the time zone of the user. As a result, all the users have an accurate sense of how long a problem or other issue has remained open.

For example, if a help desk analyst opens a problem in New York, transfers it to Chicago, then a user in Los Angeles resumes work on the problem, each user sees times relating to this problem in terms of their own time zone. The time the problem was opened appears as 8:00 a.m. to the New York user, 7:00 a.m. to the Chicago user, and 5:00 a.m. to the Los Angeles user.

Normalization

Normalization reconciles slight differences in the time clocks of the various workstations that use Tivoli Service Desk. Time data stored in the TSD database is "normalized" or altered to agree with the database time. This ensures that audit trails and actions such as escalations and automatic notifications reflect a single, consistent time reference.

Every time a user starts TSD, the difference between workstation time and database time is calculated using GMT. This is the hours, minutes and seconds that the workstation GMT is different from the current database GMT. This difference is added to the workstation time when time data stored is stored in the TSD database.

Note: If you change the time on the workstation clock while running any Tivoli Service Desk application, you must restart the TSD application in order to recalculate the time difference.

For example, a user starts TPM in Chicago and the workstation clock time is 10:30:00 (GMT 16:30:00). The database clock time in New York is 11:31:30 (GMT 16:31:30). The difference between the clocks is 00:01:30.

The user in Chicago opens a problem at 12:15:00 (GMT 18:15:00). If TSD is using normal GMT processing, the time the problem was opened is stored as 18:16:30. This is the Chicago time of 18:15:00 plus the 00:01:30, the difference between the workstation and database clocks.

Standardization

All time calculations are based on a single standard to ensure accuracy. The system administrator decides if the standard is GMT or database time. In effect, the system administrator can decide to override GMT processing and substitute time calculations based on the time of the database server. This decision directly affects the way time is stored in the database. See Overriding GMT processing.

Greenwich Mean Time

Greenwich Mean Time (GMT) is calculated from the time kept by the database server's internal clock, taking into account the time difference and daylight savings correction associated with the time zone where the database server is located. See Maintaining Time Zones.

Daylight Savings Time

Twice a year the system administrator must check that the Daylight Savings Time Action check box is correctly set, regardless of whether or not the database is located in a time zone that observes Daylight Savings Time. See Indicating Daylight Savings Time status.

Examples

Normal GMT processing

Normal GMT processing occurs when the system administrator selects GMT as the standard for time calculations by clearing the Make Selected Time Base Time check box in the Time Zone tab of the TSD System Configuration dialog box.

Example: This is how normal GMT processing works under the following conditions:

  • Daylight Savings Time is not active
  • User is in EST (Eastern Standard Time zone)
  • Database is in EST (Eastern Standard Time zone)
  • A user starts TPM and the workstation clock time is 17:20:02 (GMT 22:20:02).
  • Database time is 17:22:35 (GMT 22:22:35)
  • The normalization factor is 2:33 (the difference between the two clocks)
  • A user opens a new problem and the workstation clock time is 17:30:00 (GMT 22:30:00)

    Result: The time the problem was opened is stored in the database as 22:32:33. This is the workstation GMT plus the normalization factor of 2:33.

Example: Normal GMT processing adjusts the time stored when the Daylight Savings Time Active check box is selected on the Time Zone tab of the TSD System Configuration dialog box.

  • Daylight Savings Time is active
  • User is in EST (Eastern Standard Time zone)
  • Database is in EDT (Eastern Daylight Time zone)
  • The DST correction for the database time zone is 60 minutes
  • A user starts TPM and the workstation clock time is 17:20:02 (GMT 22:20:02)
  • The database time is 18:22:35 (GMT 22:22:35, adjusted for Daylight Savings Time)
  • The normalization factor is 2:33 (the difference between the two clocks)
    Note: The normalization factor is always calculated after Daylight Savings Time adjustments to GMT.
  • A user opens a new problem and the workstation clock time is 17:30:00

    Result: The time the problem was opened is stored in the database as 22:32:33. This is the workstation GMT plus the normalization factor of 2:33.

GMT override processing

GMT override processing occurs when the system administrator decides to use database time as the standard for time calculations by selecting the database time zone and the Make Selected Time Base Time check box in the Time Zone tab of the TSD System Configuration dialog box.

Example: This is how override GMT processing works under the following conditions:

  • Daylight Savings Time is not active
  • User is in CST (Central Standard Time zone)
  • Database is in EST (Eastern Standard Time zone)
  • A user starts TPM and the workstation clock time is 17:20:02 (GMT before override 22:20:02)
  • The database time is 18:22:35 (GMT before override 22:22:35)
  • The normalization factor is 2:33 (the difference between GMT for the two clocks)
    Note: The normalization factor is always calculated based on GMT time.
  • A GMT override value is calculated for the workstation clock.
  • When the user opens a new problem, the workstation clock time is 17:30:00 (GMT 22:30:00).

    Result: The time the problem was opened is stored in the database as 18:32:33. This is the workstation GMT after the override is applied, plus 2:33, the difference between the workstation and database clocks.

Example: Override GMT processing adjusts the time stored when the Daylight Savings Time Active check box is selected on the Time Zone tab of the TSD System Configuration dialog box.

  • Daylight Savings Time is active
  • User is in CDT (Central Daylight Time zone)
  • Database is in EDT (Eastern Daylight Time zone)
  • The DST correction for the database time zone is 60 minutes
  • A user starts TPM and the workstation clock time is 17:20:02 (GMT before override 22:20:02)
  • The database time is 18:22:35 (GMT before override 22:22:35)
  • The normalization factor is 2:33 (the difference between GMT for the two clocks)
  • A user opens a new problem and the workstation clock time is 17:30:00

    Result: The time the problem was opened is stored in the database as 18:32:33. This is the workstation GMT after the override is applied, plus 2:33 (the difference between the workstation and database clocks.