[SOLR-12511] Support non integer values for replica in autoscaling rules

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 7.5, 8.0
• Component/s: AutoScaling
• Assignee: Noble Paul
• Reporter: Noble Paul
• Created: 22/Jun/18 05:56
• Updated: 08/Jun/19 14:58
• Resolved: 02/Oct/18 00:01

Description

This means the user can configure a decimal value in replica

example :

{"replica": 1.638, "node":"#ANY"}

This means a few things. The no:of of replicas in a node can be either 2 or 1. This also means that violations are calculated as follows

• If the replica count is 1 or 2 there are no violations 
• If the replica count is 3, there is a violation and the delta is 3-1.638 = 1.362
• if the replica count is 0, there is a violation and the delta is 1.638 - 0 = 1.638
• This also means that the node with zero replicas has a more serious violation and the system would try to rectify that first before it address the node with 3 replicas

Issue Links

• is required by: SOLR-11985 Allow percentage in replica attribute in policy
• is required by: SOLR-12495 Enhance the Autoscaling policy syntax to evenly distribute replicas among nodes
• relates to: SOLR-12517 Support range values for replica in autoscaling policies