Highly detailed (verbose) log files can be generated by adding the Logging thru a registry key change, in a backup tsql script, maintenance plan, backup job, single backup or via cmd line. How to determine the source of the resulting log file.
To determine which Maintenance Plan is the one with verbose logging set, check the schedule for the Maintenance Plan against the time the log file was created.
Examples:
Trace Logging added as an additional key in HKEY_LOCAL_MACHINE\SOFTWARE\Imceda\SQLLiteSpeed\Engine in Registry:
SLS Trace Log: D:\Backup\Log Files\SLS 2011-06-29 02-02-22 3964.Log
Trace Options: Rollover=10485760, MultiLogs=false, DeleteLogs=true, Flushing=true
Traced Domain: Main: Information, Warning, Error, Exception, Threads, CallStack, ForceStack
Traced Domain: VDI: Information, Warning, Error, Exception, Threads, CallStack, ForceStack
Traced Domain: SQL: Information, Warning, Error, Exception, Threads, CallStack, ForceStack
Traced Domain: IO: Information, Warning, Error, Exception, Threads, CallStack, ForceStack
Traced Domain: AC: Information, Warning, Error, Exception, Threads, CallStack, ForceStack
Also, open the suspected Maintenance Plan for editing and click on the right-most toolbar option in the editor called "Reporting and Logging", check the Debug Logging option (set it to "None"). Verify on that same page for any Reporting options that are enabled. Also, check the same page in the Logging section and make sure the Log Extended Information and Log to Remote Server options are disabled.
