[OAK-3554] Use write concern of w:majority when connected to a replica set

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.11, 1.4
• Component/s: core, mongomk
• Labels: resilience
• Epic Link: DocumentMK resilience
• Assignee: Marcel Reutegger
• Reporter: Chetan Mehrotra
• Created: 27/Oct/15 06:41
• Updated: 02/Mar/16 15:04
• Resolved: 11/Nov/15 15:43

Description

Currently while connecting to Mongo MongoDocumentStore relies on default write concern provided as part of mongouri.

Recently some issues were seen where Mongo based Oak was connecting to 3 member replica set and there were frequent replica state changes due to use of VM for Mongo. This caused data loss and corruption of data in Oak.

To avoid such situation Oak should default to write concern of majority by default. If some write concern is specified as part of mongouri then that should take precedence. This would allow system admin to take the call of tweaking write concern if required and at same time allows Oak to use the safe write concern.

Issue Links

• is related to: OAK-1453 MongoMK failover support for replica sets (esp. shards)
• relates to: OAK-2592 Commit does not ensure w:majority