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Microsoft KB Archive/248764

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Knowledge Base


FIX: DBCC TEXTALLOC May Cause SQL Server to Stop Responding

Article ID: 248764

Article Last Modified on 9/6/2006



APPLIES TO

  • Microsoft SQL Server 6.5 Service Pack 5a



This article was previously published under Q248764

BUG #: 18930 (SQLBUG_65)

SYMPTOMS

Under memory constrained conditions, running DBCC TEXTALLOC against a table containing large text values may cause SQL Server to stop processing queries and logon requests. SQL Server may also write indefinite bufwait messages or write an access violation stack dump to the errorlog in some cases.

1999/08/30 01:31:16.11 spid20 bufwait: timeout, BUF_IO, bp 0x4cbcc40, pg 0xee1c1, stat 0x801004/0x6, obj 0x269ab60b, bpss 0x48aaf98

SQL Server may not seem to be responding and will not allow processing until the service is stopped and restarted.

CAUSE

Read-ahead was being used for the text and not the base table.

STATUS

Microsoft has confirmed this to be a problem in SQL Server version 6.5. This problem has been corrected in the Post Service Pack 5a Update for Microsoft SQL Server version 6.5. To install the Post Service Pack 5a Update, you must have either SQL Server 6.5 SP5 or SP5a installed.

For information about how to download and install the SQL Server 6.5 Service Pack 5a, refer to the following article in the Microsoft Knowledge Base:

197177 INF: How to Obtain SQL Server 6.5 Service Pack 5a


If you already have SQL Server 6.5 SP5 or SP5a installed, you can download the Post SP5a Update from the following article in the Microsoft Knowledge Base:

274036 INF: How to Obtain SQL Server 6.5 Post Service Pack 5a Update


For more information, contact your primary support provider.

MORE INFORMATION

The following error may be written to the errorlog, which may cause a concern for reconfiguring sp_configure settings:

1999/08/30 23:36:10.35 spid24 WARNING: no read ahead slots available. Use sp_configure to increase the number of slots ('RA worker threads' or 'RA slots per thread').

Increasing the read ahead settings may provide some immediate relief, but the likelihood of reoccurrence is increased as more text is added to the table.

Keywords: kbbug kbfix kbqfe KB248764