index module-index shard allocation

一、索引分片分配简介：

1、索引恢复速度，并发控制

cluster.routing.allocation.enabled:true。

cluster.routing.allocation.node_concurrent_incoming_recoveries:2

cluster.routing.allocation.node_concurrent_outing_recoveries:2

cluster.routing.allocation.node_concurrent_recoveries:2

cluster.routing.allocation.node_initial_primaries_recoveries:4

cluster.routing.allocation.same_shard.host:false

cluster.routing.rebalance.enabled:all/primaries/replicas/none

cluster.routing.allocation.all_balance:all/primaries/replicas/none

cluster.routing.allocation.cluster_concurrent_rebalance:2

2、磁盘水位，85%：不再分配节点，90%：迁出节点，95%。

cluster.routing.allocation.disk.watermark.low:85%

cluster.routing.allocation.disk.watermark.high:90%

3、机架感知

cluster.routing.allocation.awareness.attributes:zone

node.attr.zone=zone_one

cluster.routing.allocation.awareness.force.zone.values:zone_one,zone_two

4、索引分片分配过滤

cluster.routing.allocation.require/include/execute.{attribute}

attribute:_name,_ip,_tier

5、延时分配

index.unassigned.node_left.delayed_timeout