XADM: Tasks Controlled by the IS Maintenance Schedule

The Microsoft Exchange information store maintenance schedule is a configurable block of time in which common tasks are launched for maintaining the information store database. This articles describes the tasks directly controlled by the information store maintenance schedule and the order in which they start.

The information store maintenance schedule is set through the IS Maintenance tab within the properties of the Server object in the Microsoft Exchange Server site. The information store maintenance schedule is divided into 15-minute intervals, as are all schedule pages.

NOTE: If you click "Always," this means every 15-minutes.

At the start of each 15-minute interval the maintenance thread checks to see if the interval is selected. If the interval is selected, maintenance is performed. In the start of each task, the minimum time between cleanup is checked (these values are listed below and controlled by the registry settings documented only unless otherwise noted) and if the task was last completed within the minimum time, the task cannot be performed in this maintenance window (the minimum time interval overrides the information store maintenance schedule). After information store maintenance starts, it runs to completion.

The following tasks are performed at IS Maintenance time:

• Index Aging
  
  
• Tombstone Maintenance
  
  
• Message Expiration (Public Store Only)
  
  
• Age Folder Tombstones (Public Store Only)
  
  
• Update Server Versions (Public Store Only)

These tasks are described below.

Index Aging

Indexes created in database tables by the client (used for views) that have not been used for a given time are cleaned up at this time. The following registry entries are used to control index aging:

Aging Keep Time:
The minimum index age (milliseconds for Exchange 4.0 and Exchange 5.0, seconds for Exchange 5.5 and Exchange 2000) before it is deleted, the default is 8 days for Exchange 5.5 and earlier and 40 days for Exchange 2000.

Aging Clean Interval:
The minimum time interval (milliseconds) between index age task runs, the default is 24 hours.

Reset Views:
If this setting exists and it is non-zero, this forces all cached indexes to be deleted during the next index aging task run. When the index aging is complete, the Reset Views value sets to 0.

For additional information on Index Aging, please see the following Microsoft Knowledge Base article: Event logging for index aging is controlled by the following registry settings:

NOTE: The above registry keys are one path, and has been wrapped for readability.

The standard event log levels of 0 to 5 apply (5 is most verbose.)

Tombstone Maintenance

This is the process of compacting deleted message information used for local and Public Folder replication. The minimum time between tombstone maintenance task execution is 24 hours (not controllable through the registry).

There is currently no event logging available for tombstone maintenance.

Message Expiration (Public Store Only)

This is the process of expiring messages in Public Folders that are older than a specified time value. The setup for message expiration is in the Microsoft Exchange Server Administrator program on the "Age Limits" tab in the public Information Store container.

The default minimum time between expiration task execution is 24 hours with the following registry setting override (in milliseconds).

NOTE: The above registry key is one path, and has been wrapped for readability.

Event logging is controlled by the following registry key:

NOTE: The above registry key is one path, and has been wrapped for readability.

The standard event log levels of 0 to 5 apply (5 is most verbose).

Age Folder Tombstones (Public Store Only)

This is the process of removing folder tombstone entries that are older than a given time (default is 180 days). Folder tombstone information is used by public folder replication. The aging is required to prevent the folder tombstone list from growing unbounded. The default value of 180 days can be overridden with a registry variable (value is in days):

NOTE: The above registry key is one path, and has been wrapped for readability.

The default minimum time between folder tombstone aging task execution is 24 hours with no registry override.

There is currently no event logging available for age folders tombstones.

Update Server Versions (Public Store Only)

The Directory Service stores the Microsoft Exchange Server version number for each server. At regular intervals, this information is read from the Directory Service and stored in memory for use by the public store. This information is used to control interoperability between current and older versions of Microsoft Exchange Server. As servers are upgraded, this info needs to be updated. Default minimum time between server version updates is 24 hours, with no registry override.

There is currently no event logging available for updating server versions.

Article Index Expiration (Public Store Only)

Default minimum time between article index expiration task execution is 60 minutes with a registry override:

NOTE: The above registry key is one path, and has been wrapped for readability.

The default article age is 7 days before it is expired with a registry override:

NOTE: The above registry key is one path, and has been wrapped for readability.

NOTE: The information store maintenance tasks all run under the same thread at THREAD_PRIORITY_BELOW_NORMAL. Each task runs sequentially. The thread is allocated when information store maintenance is performed, and freed when it is complete.

NOTE: There are other tasks that can be considered maintenance tasks, but they are not controlled by the information store maintenance schedule.

For more information on these tasks, please see the following Microsoft Knowledge Base article: