Active Directory Database Monitoring

  • Article

Applies To: Operations Manager 2007, Windows Server 2012

Active Directory Database Monitoring verifies that the underlying files used to host the directory (sometimes referred to as the DIT) are in a consistent state, and that there is available room for the database files to grow. This includes both the database files and the log files on each domain controller that is monitored by the ADMP.

The Active Directory Database and Log File workflow monitors database and log file size and available free space on the associated disk volumes. By default, the script runs every 15 minutes, and it calls the OOMADs Component Object Model (COM) object to obtain data.

The Active Directory Database and Log File script first calls OOMADs.GetDatabaseInfo. If that call succeeds, the script stores the returned values for drive free space and database size as performance data. The script then calls OOMADs.GetLogFileInfo. If that call succeeds, the script stores the returned values for drive free space and database log size as performance data. If both calls succeed, the script attempts to determine if a significant decrease has occurred in the amount of free space on either drive, and, if possible, it identifies the cause of the free space reduction.

To make this determination, the script records the following data:

  • Active Directory Database (DIT) Size

  • Log Size

  • Free DB Space

  • Free Log Space

  • SYSVOL Size

  • Last Run Time

Database and Log File Growth

When a domain controller is not in its first replication cycle, the Active Directory Database and Log File script performs a test to determine whether excessive growth in either the database or the log files is occurring.

Note

Immediately after Active Directory deployment and a computer becomes a domain controller, an initial, complete replication cycle must occur before the domain controller begins advertising its services on the network. During this initial replication cycle, the database and log file sizes are expected to grow significantly. This growth is not reported by the script as an error. However, for a new domain controller, the script still reports any low-disk-space conditions.

To determine whether the domain controller is in its initial replication cycle, an attempt is made to read the replUpToDateVector attribute on the LDAP://RootDSE object of the local computer. If the attribute exists, the domain controller has already completed its first replication cycle.

A comparison of the current and previous values for database and log file size is used to determine whether the database or log has grown more than 20 percent since the last time that the script ran. If excessive growth has occurred, an event is generated that indicates the amount of growth and the time difference (in minutes) between the current and previous measurements.

Note

The 20-percent value is fixed, and it cannot be configured by the user.

Required Disk Space

If the database and log files reside on separate logical drives, the script verifies that the logical drive holding the database file has the greater of 500,000 kilobytes (KB) or 20 percent of the current database size available. The script also verifies that the logical drive holding the log file has the greater of 200,000 KB or 5 percent of the current database size available.

If the database and log files reside on the same logical drive, the script verifies that the greater of 700,000 KB or 25 percent of the current size of the database is available on the drive.

First, the script determines whether the database and log files reside on the same logical drive. The script makes this determination by comparing the first two characters of the file path for both the database and the log files. (If one path uses a Universal Naming Convention [UNC] path name and the other path uses a drive\directory path name, the check fails.)

If both files reside on the same drive, the amount of free space that is required on the database drive is added to the amount of free space on the log drive.

The required amount of free space is then checked against the available free space. If the required free space is greater than the available free space, an event is generated. The event contains the current free space on the drive and the calculated, required free space on the drive.

Configuration

There are no recommended configuration settings for this scenario.