Microsoft KB Archive/177127

= Incorrect report on disk free space under DFS =

Article ID: 177127

Article Last Modified on 8/23/2007

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APPLIES TO


 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows 95
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Server
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Home Edition
 * Windows Vista Business
 * Windows Vista Enterprise
 * Windows Vista Home Premium
 * Windows Vista Ultimate

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This article was previously published under Q177127





SYMPTOMS
The Disk Free Space reported in Windows Explorer or in a Command Prompt on a Distributed File System (DFS) client for a DFS share is always the Disk Free Space of the drive containing (hosting) the DFS root.



CAUSE
This problem occurs because of a limitation in the server message block (SMB) protocol. The only SMB packet that is available to obtain the free disk space of a volume is TRANS2_QUERY_FS_INFORMATION with a sub-command of SMB_QUERY_FS_SIZE_INFO. Unfortunately, this command uses the Tree ID from the tree connect to determine which volume to query. If you access a mount point through a share on another volume, the tree connect happens to the share. Therefore, the Tree ID refers to the volume that the share is on, not on the volume that the mount points to. This limitation is scheduled to be fixed in the SMB 2.0 protocol.



MORE INFORMATION
The free disk space information that you see in Windows Explorer or ithat you see by running a command-line command on a domain based Distributed File System (DFS) is incorrect. You see disk information about the drive that hosts the SYSVOL share of the Domain Controller you are connected to. Additionally, "Free space" and "Used Space" information may be displayed incorrectly in Windows Explorer. This problem occurs if you have mapped a drive to a share that links to a mounted volume by using NTFS volume mount points or by using symbolic links.

Microsoft has confirmed this to be a problem in Windows NT version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

