Large Files Copy Slowly from a Macintosh Computer to a Windows Server 2003-Based Computer That Is Running Services for Macintosh

Last Updated: October 26, 2006

Microsoft Article ID : 823356
Revision : 9.4


When you copy a large file from a Macintosh computer to a Microsoft Windows Server 2003-based computer that is running Services for Macintosh, the file copies slowly.

This issue may occur if Windows Server 2003 does not send the final Reply-DSI-Write signal during the transfer of each data block. The Macintosh computer must wait for this signal before it can send more data. When the Macintosh computer does not receive this signal, it waits for about 50 milliseconds, and then it sends an ACK signal to the Window Server 2003-based computer. The ACK signal causes Windows Server 2003 to send the Reply-DSI-Write signal, and the file copy continues. When you copy a large file, these delays add up and increase the time it takes to copy the file.


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: (

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.

File Information

The English version of this has the file attributes (or later) 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 tool in Control Panel.

Date Time Version Size File name Platform
20-Jun-2003 18:47 5.2.3790.65 156,160 Sfmsrv.sys x86
20-Jun-2003 18:47 5.2.3790.65 466,944 Sfmsrv.sys ia64


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



  • Microsoft Windows Server 2003, Standard Edition (32-bit x86)
  • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)