XADM: Tasks Controlled by the IS Maintenance Schedule

• Microsoft Exchange Server, version 4.0

SUMMARY

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 IS Maintenance Schedule and the order in which they start.

MORE INFORMATION

The IS Maintenance schedule is set through the IS Maintenance tab within the properties of the Server object in the Microsoft Exchange site. The IS 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 it is selected, maintenance is performed. In starting 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 will not be performed in this maintenance window (the minimum time interval will override the IS Maintenance schedule). Once IS Maintenance is started it will run 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)

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: minimum index age (milliseconds) before it is deleted,
   default is 8 days

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

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

   For additional information on Index Aging, please see the following
   article in the Microsoft Knowledge Base:

      ARTICLE-ID: Q159157
      TITLE     : XADM: Controlling Folder Index Aging

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
   Diagnostics\Private\General\Views

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
   Diagnostics\Public\General\Views

Tombstone Maintenance:

This is the process of compacting deleted message information used for local and Public Folder replication. 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).

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
   ParametersPublic\Replication Expiry

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
   Diagnostics\Public\Replication\Expiry

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):

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
   ParametersPublic\Replication Folder Tombstone Age Limit

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.

NOTE: The IS Maintenance tasks all run under the same thread at THREAD_PRIORITY_BELOW_NORMAL. Each task runs sequentially. The thread is allocated when IS 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 IS Maintenance Schedule.