You may experience a decrease in overall system performance when you are copying files that are larger than approximately 500 MB in Windows Server 2003 SP1 (920739)

CAUSE

This problem occurs when you copy large files locally from a fast disk to a slow disk. For example, this problem can occur when you copy large files from a cluster disk to local system disk.

The System Internals Cache Manager uses a variable that is named CcDirtyPageThreshold. By default, the value of CcDirtyPageThreshold may be set too high for scenarios where there are many lazy writes. By default, the CcDirtyPageThreshold global kernel variable is set to a value that is half of the physical memory. This variable triggers the cache manager's write throttles.

For example, if you are copying a file that is 1 GB, 500 MB of the file is copied to the cache before the Cache Manager starts flushing the dirty pages. Flushing 500 MB of dirty pages causes several page faults. These page faults must be committed to the disk. When this occurs, it can cause bottlenecks on slow disks.

Note A "dirty page" is a page that has been modified in the cache but has not yet been written to disk.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows Server 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

You must be running Windows Server 2003 Service Pack 1 (SP1).

Restart requirement

You must restart your computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.Windows Server 2003, Itanium-based version

File name	File version	File size	Date	Time	Platform
Ntkrnlmp.exe	5.2.3790.2725	6,502,912	15-Jun-2006	11:45	IA-64

Windows Server 2003, x64-based version

File name	File version	File size	Date	Time	Platform	SP requirement	Service branch
Ntkrnlmp.exe	5.2.3790.2725	4,626,432	15-Jun-2006	11:45	x64	SP1	SP1QFE
Ntoskrnl.exe	5.2.3790.2725	4,481,024	15-Jun-2006	11:45	x64	SP1	SP1QFE

Windows Server 2003, x86-based version

File name	File version	File size	Date	Time	Platform	SP requirement	Service branch
Ntkrnlmp.exe	5.2.3790.2725	2,458,112	15-Jun-2006	10:12	Not Applicable	SP1	SP1QFE
Ntkrnlpa.exe	5.2.3790.2725	2,270,208	15-Jun-2006	09:41	x86	SP1	SP1QFE
Ntkrpamp.exe	5.2.3790.2725	2,310,656	15-Jun-2006	09:41	Not Applicable	SP1	SP1QFE
Ntoskrnl.exe	5.2.3790.2725	2,418,688	15-Jun-2006	10:12	x86	SP1	SP1QFE

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

After you apply this fix, you must add the SystemCacheDirtyPageThreshold registry entry to change the default behavior. To do this, follow these steps:

Click Start, click Run, type regedit, and then click OK.
Locate and then right-click the following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\SessionManager\MemoryManagement
Point to New, and then click DWORD Value.
Type SystemCacheDirtyPageThreshold, and then press ENTER.
Double-click SystemCacheDirtyPageThreshold.
In the Value data box, type an appropriate value, and then click OK.

Note The range of values for the SystemCacheDirtyPageThreshold registry entry are as follows:
Minimum value: Total physical RAM in MB divided by 64
Maximum value: Total physical RAM in MB divided by 2
Default value: 0

The default value is a non-existent key. If you add values that are out of range, your computer will revert to the default behavior. The value that you add is measured in MB.
Exit Registry Editor.