Microsoft KB Archive/235250

= I/O May Be Performed at the Wrong Offset with Files Larger than 4 GB =

Article ID: 235250

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q235250



SYMPTOMS
Certain file read or write operations (also known as input/output, or I/O operations) may be performed at incorrect locations within a file that is larger than 4 gigabytes (GB) in size.

For this problem to occur, I/O operations must be cached and asynchronous. Unbuffered, synchronous operations are not susceptible to the problem described in this article.

This problem can occur only when two I/O operations are performed in close succession if the first operation is above the 4-GB mark and the second operation is at the same offset (modulo 4 GB), below the 4-GB mark.

For example, if the first operation is performed at offset 4,295,032,832 (0x100010000 hex) and the second is performed at offset 65,536 (0x10000 hex), the second I/O operation may actually take place at the first offset.



CAUSE
In an attempt to improve performance, the cache manager attempts to perform 32-bit operations when performing certain lookup operations. 64-bit operations are more time consuming, but are required when file offsets are large enough that they cannot be represented in 32 bits. The problem described in this article occurs because the cache manager occasionally errs and performs 32-bit arithmetic when 64-bit arithmetic is required.



Windows NT Server or Workstation 4.0
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:


 * http://www.microsoft.com/windows/servicepacks/ -or-


 * 152734how to obtain the latest windows nt 4.0 service pack

For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://support.microsoft.com/directory/overview.asp

Windows NT Server 4.0, Terminal Server Edition
To resolve this problem, obtain the latest service pack for Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack



STATUS
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition.

This problem was first corrected in Windows NT Server 4.0 Service Pack 6 and Windows NT Server 4.0, Terminal Server Edition Service Pack 6.

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe KB235250

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