[HDDS-5441] Disallow same set of DNs to be part of multiple pipelines

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Component/s: SCM
• Labels: pull-request-available
• Assignee: Shashikant Banerjee
• Reporter: Shashikant Banerjee
• Created: 14/Jul/21 14:55
• Updated: 23/Feb/24 00:05
• Resolved: 04/Aug/21 08:02

Description

Currently, with multi raft feature ON, a data node can participate in multiple pipelines. But, same set of dns can be part of multiple pipelines . This leads to 2 problems:

1) In case of let's say 5 datanodes, as and when 3 datanodes register initially with multi-raft feature ON, those 3 datanodes will pair among themselves to create two pipelines thereby satisfying the default pipeline limit of 2 per dn. Next datanodes even after registering cannot take part in writes bcoz it needs a 6th datanode to come up to form the nest tri-set , thereby remain unutilized.

2) With same set of Datanodes being part of multiple plpelines, if one datanode fails, the source for container re-replication will be only the other set of 2 nodes and can beocme a bottleneck.

3) This uneven distribution of pipelines among dns will lead to load distribution getting uneven as well.

 

 

Issue Links

• is cloned by: HDDS-5135 Datanode should be paired with different set of datanodes for multiraft
• is related to: HDDS-4689 Autoclose pipeline after 'n' containers to distribute pipeline and containers over multiple datanodes
• is related to: HDDS-6225 Pipelines distribution across datanodes is uneven
• links to: GitHub Pull Request #2416