Hi, thanks for filing this report. I thought we'd have fixed this one long time ago, but apparently not Maybe you feel adventureous and would like to give it a try to fix this?

Technically, there are two operations passed from the Hibernate OGM core to the MongoDBDialect:

• An insert for the LogEntry
• An insert for the LogEntry_Subsystems association
• 
  The idea would be use the "batching" feature of MongoDBDialect to collect both commands and issue only one request to the datastore. As said, I assumed there'd be code for this already in place, but I may be dreaming or it's somehow broken.