System maintenance tasks are typically run every night to clear unused data, update database statistics, perform nightly data refreshes, and keep these server running smoothly and quickly.

To configure system maintenance, select Admin > Admin Console and click System Maintenance.

We recommend leaving all system maintenance tasks enabled, but some of the tasks can be disabled if absolsolutely necessary. By default, all enabled tasks run on a daily schedule at the time of day you select (see below for notes about Daylight Savings Time). You can also run system maintenance tasks manually, if needed; use the Run all tasks link or click on an individual link to run just that task.

System maintenance runs as a pipeline job and logs progress, information, warnings, and errors to the pipeline log. To view previously run system maintenance pipeline jobs, select Admin > Admin Console and click Pipeline.

System Maintenance Schedule and Daylight Savings Time

Note: Specifics of the transition hour and the amount of time the clock moves forward or back varies by locale; see: https://secure.wikimedia.org/wikipedia/en/wiki/Daylight_saving_time_around_the_world

System maintenance triggering is potentially subject to some oddities twice a year, when Daylight Savings Time transitions occur. As an example, in the United States, within time zones/locations that observe Daylight Savings Time, the following problems may occur if system maintenance is scheduled between the hours of 1:00AM and 3:00AM:

• 1:15AM may occur twice - duplicate firings are possible
• 2:15AM may never occur - missed firings are possible

Missing or re-running system maintenance twice a year will generally not cause any problems, but if this is a concern then schedule system maintenance outside the DST transition times for your locale.

This section is paraphrased from the Quartz Scheduler documentation; see "Daylight Savings Time" section of this page: http://quartz-scheduler.org/documentation/best-practices