Microsoft KB Archive/321543

= Slow Network Performance After You Promote a Windows 2000-Based Server to a Domain Controller =

Article ID: 321543

Article Last Modified on 3/1/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server

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This article was previously published under Q321543



SYMPTOMS
If you upgrade a Windows 2000-based server to a domain controller, you may experience performance degradation on some hardware. For example, after the upgrade, network performance may be slower if you copy files to a share on a Windows 2000-based domain controller than if you copy the same files to a Windows 2000-based member server.

The following event ID message may be logged in the event log after you run the Dcpromo tool:

Event ID: 13512

Type: Warning

Description:

The File Replication Service has detected an enabled disk write cache on the drive containing the directory %2 on the computer %1. The File Replication Service might not recover when power to the drive is interrupted and critical updates are lost.



CAUSE
This problem may occur if a disk's write caching functionality has been turned off. If you use the Dcpromo tool to promote a Windows 2000-based server to a domain controller, the write caching functionality (write-back cache is a firmware function) is turned off for any of the logical drives that contain the Active Directory database or log files, including the system disk. Write caching is turned off because the File Replication Service (FRS) does not recover if power to the drive is interrupted and if critical updates are lost.



RESOLUTION
To prevent this problem from occurring, use a domain controller that has a file server to separate the system disk and the partitions where the Active Directory log file and database files are located from the data disks on which your file shares reside. Microsoft recommends that you place log files and database files on separate physical disks to improve performance and to help with data recovery.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.



Caching and Data Recovery
The cache is the area of RAM that contains data. When you write data to disk, the lazy-write technique in Windows 2000 indicates that the data is written; however, the data is still in the cache. Cache memory also exists on the disk controller (for example, small computer system interface [SCSI] controllers) or on the disk unit (for example, Enhanced integrated device electronics [EIDE] disks). Review the following information to decide whether you want to turn on the disk or controller cache:
 * If you turn on write caching, disk performance improves, particularly if the disk is being heavily written to.
 * Control of the write-back cache is a firmware function that is provided by the disk manufacturer. See the documentation supplied with the disk or disk controller. You cannot configure the write-back cache from Windows 2000.
 * Write caching does not affect the reliability of the file system's own meta data. NTFS instructs the disk device driver to make sure that meta data writes get written regardless of whether write caching is turned on. Non-meta data is typically written to the disk, so this kind of data can be cached.
 * Read caching in the disk has no effect on file system reliability.

On RAID 5 volumes and stripe sets, reading is faster than writing. Mirrored volumes also are typically faster at reading than writing, and are faster at writing than RAID 5 volumes.

For more information about Disk Tuning see the Server Operations Guide in the Windows 2000 Server Resource Kit.

For additional information about the write caching functionality, click the article numbers below to view the articles in the Microsoft Knowledge Base:

281672 Possible Data Loss After You Enable the 'Write Cache Enabled' Feature

233541 Description of Advanced Disk Properties Features

259716 HOW TO: Manually Enable/Disable Disk Write Caching

For more information about possible causes of slow performance on Windows 2000 domain controllers that operate with Windows XP client computers, click the following article numbers to view the articles in the Microsoft Knowledge Base:

321098 Slow network performance occurs if you copy files to a domain controller that is running Windows 2000 or Windows Server 2003

282071 Users Are Accessing a DFS Root Replica in a Remote Site

279637 Client Performance Is Inconsistent in a Windows 2000-Based Domain That Uses Kerberos Authentication

264822 File Replication Service Stops Responding When Staging Area Is Full

321169 Slow SMB Performance When You Copy Files from Windows XP to a Windows 2000 Domain Controller

Additional query words: slow poor performance tuning file copy slowness speed decreased slowdown bad degrade W2K Win2000 DC diskcache

Keywords: kbperformance kbprb KB321543

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