[SOLR-11005] inconsistency when maxShardsPerNode used along with policies

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: AutoScaling, SolrCloud
• Assignee: Noble Paul
• Reporter: Noble Paul
• Created: 04/Jul/17 14:06
• Updated: 28/Apr/20 14:52
• Resolved: 16/Mar/18 13:39

Description

The attribute maxShardsPerNode conflicts with the conditions in the new Policy framework

for example , I can say maxShardsPerNode=5 and I can have a policy

{ replica:"<3" , shard: "#ANY", node:"#ANY"}

So, it makes no sense to persist this attribute in collection state.json . Ideally, we would like to keep this as a part of the policy and policy only.

proposed new behavior

if the new policy framework is being used

{maxShardsPerNode}

should result in creating a new collection specific policy with the correct condition. for example, if a collection "x" is created with the parameter maxShardsPerNode=2 we will create a new policy in autoscaling.json

{
"policies":{
"x_COLL_POLICY" : [{replica:"<3", shard:"#ANY" , node:"ANY"}]
}
}

this policy will be referred to in the state.json. There will be no attribute called maxShardsPerNode persisted to the state.json.

if there is already a policy being specified for the collection, solr should throw an error asking the user to edit the policy directly

the name is bad

We must rename the attribute maxShardsPerNode to maxReplicasPerNode. This should be a backward compatible change. The old name will continue to work and the API would give a friendly warning if the old name is used

Issue Links

• is superceded by: SOLR-11239 Deprecate maxSHardsPerNode when autoscaling policies are used
• relates to: SOLR-10733 Rule-based Replica Placement not working correct
• relates to: SOLR-9735 Umbrella JIRA for Auto Scaling and Cluster Management in SolrCloud