Microsoft KB Archive/90133

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PRB: Databases Truncated with LAN Manager 2.1a and Earlier
'Article ID: Q90133

Creation Date: 11-OCT-1992

Revision Date: 19-SEP-1996' The information in this article applies to:


 * Microsoft Access versions 1.0, 1.1, 2.0
 * Microsoft LAN Manager versions 2.1a and earlier

SYMPTOMS

Advanced: Requires expert coding, interoperability, and multiuser skills.

Microsoft LAN Manager versions 2.1a and earlier can causes file truncation when the workstation (client) computer is faster than the server. This is not specific to Microsoft Access, but can cause damage to a networked database if Microsoft Access is used in conjunction with Microsoft LAN Manager versions 2.1a and earlier.

CAUSE

When a client workstation sends information to the server through LAN Manager version 2.1a or earlier, LAN Manager performs a &quot;lazy&quot; write (the data is buffered in memory and then written to disk at a later time). If the client workstation sends information to the server too quickly, the server sends a message to the client telling it to send information more slowly or to wait. With LAN Manager versions 2.1a and earlier, this &quot;slow down&quot; message is misinterpreted by the client redirector and the client writes 0 bytes to the file, effectively truncating it where the write operation was occurring.

This behavior is specific to the lazy writing process. When the client writes to the server, it sends the data in a burst. This burst overloads the server and elicits the slow down message.

RESOLUTION

To work around this behavior, disable the lazy write function of the LAN Manager client. To do so, add the following line to the [Workstation] section in the LANMAN.INI file:

;.............012345678901234567890123456789012  wrkheuristics=X0XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX NOTE: The top line with the numbers is only a comment line for spacing. The total number of x's and 0's (zeros) is 33 decimal. STATUS

This behavior does not occur in Microsoft Windows for Workgroups or in Microsoft Windows 95.
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Additional reference words: 1.00 1.10 2.00 lanman corruption 2.10a 2.10

KBCategory: kbsetup

KBSubcategory: StpNet