How does DPX truncate logs for Microsoft SQL database during block level backup?

Summary

How does DPX truncate logs for Microsoft SQL database during block level backup?

Question

How does DPX truncate logs from SQL during block level backup?

Answer

DPX uses SQL SMO  (bexsmo.exe) and the T-SQL command “BACKUP LOG <Instance> TO <Path>” to backup transaction logs where <Path> is \DPXSQLLogBkup\<Instance> temp folder under the drive where <Instance> logs are configured to reside on.
This happens before taking the VSS snapshot so the backup job will back up the logs since the SMO command truncates logs.
At the end of a successful backup the temp folder will be cleaned up; otherwise it is kept so next run will back it up.