Well in this case our support engineer is absolutely correct. Since you manually set "Do not truncate logs
" flag for the backup job, I'm afraid there is no way for SQL Server to understand that it should truncate the transaction log files for the Simple and keep these logs untouched for databases with Full Recovery mode selected.
davidb1234 wrote:Even when using simple recovery mode log files can grow large during big transactions. However when the database is backed up the log file is truncated by SQL automatically.
Yes, that's true, but my point was that even though transaction log can grow significantly, SQL Server will still truncate it right after this log reaches the transaction checkpoint.