[SOLR-11523] suggestions to remove nodes

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Component/s: AutoScaling
• Assignee: Unassigned
• Reporter: Noble Paul
• Created: 21/Oct/17 00:40
• Updated: 14/Aug/21 01:33
• Resolved: 14/Aug/21 01:33

Description

It is possible that the cluster is operating sub optimally with more nodes than required. It is not possible for Solr to automatically identify a suboptimal utilization of nodes.  We expect the user to provide us with policy rules to identify it

examples:

 {"cores" : ">2", "node":"#ANY" , "strict" : false }
 {"freedisk" : "<10", "node":"#ANY" , "strict": false}

Solr would go through all these rules to identify if it breaks any such rules. If yes, it would go through the following steps

1. Identify all violations to such rules
2. Sort all nodes and identify the least loaded nodes
3. If there is an empty node
   1. store that node name
   2. Simulate removal of that node and go to step #1
4. Check if they are violating these rules
5. if yes, simulate moving them to other nodes with more load
6. if it is possible, to move without breaking rules,
   1. store that suggestion
   2. Go to step #1
7. If not possible, get the list of move operations (step #6.1) and collect the list of nodes to be removed ( step # 3.1)