[HDDS-9257] LegacyReplicationManager: Unhealthy replicas could block under replication handling

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.4.0
• Component/s: SCM
• Labels: pull-request-available
• Target Version/s: 1.4.0
• Assignee: Siddhant Sangwan
• Reporter: Siddhant Sangwan
• Created: 08/Sep/23 15:10
• Updated: 21/Dec/23 10:25
• Resolved: 12/Sep/23 16:43

Description

The legacy replication manager currently resolves mismatched replicas (those whose replica state do not match SCM's container state) by
1. Replicating the matching replicas until they are fully replicated.
2. Deleting the mismatched replicas.
This approach does not work when LRM is presented with the following situation:
SCM state: CLOSED
5 datanodes in the cluster
Replica states CLOSED CLOSED QUASI QUASI QUASI
LRM will not make progress because there is no datanode to add a closed replica to that does not already have a replica.

Issue Links

• is related to: HDDS-8536 ReplicationManager: Unhealthy replicas could block Ratis containers being recovered
• links to: GitHub Pull Request #5261