Microsoft KB Archive/123029

= WFW 3.11 Clients Hang Accessing Windows NT Server =

Article ID: 123029

Article Last Modified on 12/6/2003

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APPLIES TO


 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Workstation 3.1
 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows for Workgroups 3.2

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This article was previously published under Q123029





SYMPTOMS
Windows for Workgroups version 3.11 hangs when you run a database application that is using a shared file on a Windows NT server.



CAUSE
This problem involves oplock, byte-range lock, and lock-&-close server message block (SMB) protocols. The behavior that causes this problem is as follows:


 * 1) CLIENT1 has a file open with an exclusive oplock and is using the file.
 * 2) CLIENT2 tries to open the file.
 * 3) SERVER sends an oplock break request to CLIENT1.
 * 4) CLIENT1 (MIDx) sends and oplock broken (locktype = x'02'). Even though locktype = x'02', the SMB specifies to lock range 0-EOF.
 * 5) CLIENT1 (MIDy) sends an unlock&close request specifying 0-EOF.
 * 6) SERVER (MIDy) responds with "no such lock" error. SERVER did not close the file because the unlock request failed.
 * 7) SERVER (**MIDx) responds indicating successful lock on range 0-EOF.
 * 8) CLIENT1 thinks file is unlocked and closed.
 * 9) SERVER still has file opened with locked range 0-EOF.
 * 10) Other clients will get lock error when they try to access the file.

A deadlock condition occurs since CLIENT1 thinks that the file handle was closed and therefore will never unlock the byte range.



RESOLUTION
A workaround for this problem is to turning off opportunistic locking at the file server.



STATUS
Microsoft has confirmed this to be a problem in Windows 3.11. A fix to this problem is in development, but has not been regression-tested and may be destabilizing in production environments. Microsoft does not recommend implementing this fix at this time. Contact Microsoft Product Support Services for more information on the availability of this fix.

Keywords: KB123029

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