Many backup files accumulate in C:\Program Files\DyKnow\Server\Backups. By default, DyKnow Server keeps only the last 7 days of backup files. If you have not changed this default setting and have significantly more than 7 days of backup files, you may be encountering this problem.
The cleanup process of the backup job relies on the xp_cmdshell component of SQL Server. If this is disabled, the job log will report errors containing "SQL Server blocked access to procedure 'sys.xp_cmdshell' of component 'xp_cmdshell' because this component is turned off as part of the security configuration for this server."
You can enable xp_cmdshell by executing the following script in SQL Server Management Studio:
-- To allow advanced options to be changed. EXEC sp_configure 'show advanced options', 1; GO -- To update the currently configured value for advanced options. RECONFIGURE; GO -- To enable the feature. EXEC sp_configure 'xp_cmdshell', 1; GO -- To update the currently configured value for this feature. RECONFIGURE; GO
When xp_cmdshell is enabled, backups older than 7 days (default) should be removed the next time the backup job is run.