Performance Tuning Wins and DHCP

The Microsoft Windows NT Windows Internet Name Service (WINS) and Dynamic Host Configuration Protocol (DHCP) services are usually limited in performance by the disk subsystems that hold their databases. This article discusses how to improve the performance of these services.

The Microsoft WINS and DHCP service use the Microsoft Jet database engine. The Jet database engine is a high performance system that provides reliable transaction processing by confirming to WINS or DHCP that it has positively written data to disk. This requires a mechanical operation to be performed and confirmed for each database operation. If the database is flooded with transactions, the performance of the service will be blocked while waiting for the confirmation of disk writes. Therefore, highest performances can only be achieved using a high performance hard disk subsystem.

When selecting a disk subsystem, these general rules should be followed:

• SCSI is preferable to IDE.
• Fast wide SCSI is preferable to narrow/standard SCSI.
• RAID level 5 is preferable to a single disk.
• A hardware-based RAID controller is preferable to software RAID.
• More spindles are preferred over fewer spindles, to distribute writes.
• A caching disk controller is preferable to a noncaching controller, but a caching controller must have a battery backup to ensure data integrity.

In all cases, Microsoft recommends consulting the Windows NT Hardware Compatibility List (HCL) for computers and subsystems that are certified to run with Windows NT.

It is important to stress that a caching controller must have a battery backup, because not having one creates the possibility that a controller will confirm to the file system that it has successfully written to disk without the write being performed. If there is a loss of power or other catastrophic failure, the transaction may be lost. Caching controllers with battery backup will commit cached transaction to disk when the disk subsystem is restarted, allowing the database to be consistent with transactions that have been confirmed.

Another optimization that is available to WINS, but currently not to DHCP, is the manual configuration of a log file path. As a performance optimization, the Jet database engine quickly writes transaction log files to disk that are then later written (committed) to the main database file when time permits. By configuring the log file path to a different disk subsystem than the main database file, further optimization can be achieved.

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

The logfile path is configured in the Windows NT registry under the following key:

This key should only be configured if the specified log file path points to a directory on a high performance subsystem, as writing to log files is usually the bottleneck in Wins server performance.

For additional information, see the following article or articles in the Microsoft Knowledge Base: