继上篇处理分片分配失败的故障处理，去官网整理了ES分片的所有UNASSIGNED的原因，留以备用。
INDEX_CREATED
Unassigned as a result of an API creation of an index.
索引创建 由于API创建索引而未分配的
CLUSTER_RECOVERED
Unassigned as a result of a full cluster recovery.
集群恢复 由于整个集群恢复而未分配
INDEX_REOPENED
Unassigned as a result of opening a closed index.
索引重新打开
DANGLING_INDEX_IMPORTED
Unassigned as a result of importing a dangling index.
导入危险的索引
NEW_INDEX_RESTORED
Unassigned as a result of restoring into a new index.
重新恢复一个新索引
EXISTING_INDEX_RESTORED
Unassigned as a result of restoring into a closed index.
重新恢复一个已关闭的索引
REPLICA_ADDED
Unassigned as a result of explicit addition of a replica.
添加副本
ALLOCATION_FAILED
Unassigned as a result of a failed allocation of the shard.
分配分片失败
NODE_LEFT
Unassigned as a result of the node hosting it leaving the cluster.
集群中节点丢失
REROUTE_CANCELLED
Unassigned as a result of explicit cancel reroute command.
reroute命令取消
REINITIALIZED
When a shard moves from started back to initializing, for example, with shadow replicas.
重新初始化
REALLOCATED_REPLICA
A better replica location is identified and causes the existing replica allocation to be cancelled.
重新分配副本