BUG: Scheduled Tape Dumps Fail w/ Error Unknown

  - Microsoft SQL Server, version 4.21

SYMPTOMS

On a random basis, a scheduled backup to tape may fail, and the Scheduled Backup History Report will show the error as "Unknown!". No other errors are logged in the SQL Server error log or in the Windows NT Event Viewer. However, the same dump, when automatically retried later, will succeed. If you Examine the tape with the SQL Tape Utility, it will show that the original dump also succeeded.

CAUSE

SQL Monitor is not receiving a command to mount the tape. After SQL Monitor times out, SQL Server performs the dump using the batch mode.

WORKAROUND

Currently, there is no known workaround. An alternative is to write a command file using ISQL.EXE to execute a SQL script that dumps the databases. Then use the AT command built into Windows NT to execute the dump at a later time.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SQL Server version 4.21. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.