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Possible Network Data Corruption If Locking Not Used

This article was previously published under Q152186
This article has been archived. It is offered "as is" and will no longer be updated.
When you use certain programs to access a common data file over thenetwork from multiple workstations, the data may be read incorrectly ormay become damaged.
The Microsoft Client for Microsoft Networks and Microsoft Client forNetWare Networks cache some network data on the client computer forenhanced network performance. If the program does not use locking calls toguarantee data synchronization and integrity, this cached data may not bekept in synchronization with the data on the network server.

If an opened file is not locked, it may be cached by the client. If thefile is then modified by a second client, the first client may readincorrect file data from the cache, instead of reading the current filedata from the network server. Subequent writes by the first client mayresult in incorrect data being written to the file, and damage to the filedata.
Contact the program's manufacturer for additional information about usingthe program with Windows 95.

This problem no longer occurs in Windows 98. To resolve this problem, install the current version of Windows. For information about the current version of Windows, visit
When locking calls are not used, the integrity of data cannot beguaranteed by a network client that employs caching for enhancedperformance. Such network clients include the Microsoft Client forNetWare Networks and the Microsoft Client for Microsoft Networks includedin Windows 95.

If a program locks the file or range of bytes that it intends to read fromor write to, the server locks that file, or that range of the file. Thisdenies access to that data to other users, and forces the client to readthe current data from the server instead of from the cache. This techniqueis advised for maintaining data integrity when required, while providingthe performance benefits of caching when it is safe to do so.


Article ID: 152186 - Last Review: 09/30/2013 22:18:41 - Revision: 2.1

Microsoft Windows 95

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