# Cluster Allocation Explain API 原文链接 : [https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html) 译文链接 : [http://www.apache.wiki/display/Elasticsearch/Cluster+Allocation+Explain+API](http://www.apache.wiki/display/Elasticsearch/Cluster+Allocation+Explain+API) 贡献者 : [那伊抹微笑](/display/~wangyangting) **cluster allocation explanation API** 的目的是帮助回答这个问题 “为什么这个分片没有被分配”。为了说明分片的分配（未分配状态），发出一个这样的请求 :  ``` $ curl -XGET 'http://localhost:9200/_cluster/allocation/explain' -d'{ "index": "myindex", "shard": 0, "primary": false }' ``` 指定您希望查看的说明的 **index** 和 **shard** 的 **id**，和 **primary** 标记一样来指出是否 **explain** 一个主或者副本分片。 该响应如下 :  ``` { "shard" : { "index" : "myindex", "index_uuid" : "KnW0-zELRs6PK84l0r38ZA", "id" : 0, "primary" : false }, "assigned" : false, ① "shard_state_fetch_pending": false, ② "unassigned_info" : { "reason" : "INDEX_CREATED", ③ "at" : "2016-03-22T20:04:23.620Z" }, "allocation_delay_ms" : 0, ④ "remaining_delay_ms" : 0, ⑤ "nodes" : { "V-Spi0AyRZ6ZvKbaI3691w" : { "node_name" : "H5dfFeA", "node_attributes" : { ⑥ "bar" : "baz" }, "store" : { "shard_copy" : "NONE" ⑦ }, "final_decision" : "NO", ⑧ "final_explanation" : "the shard cannot be assigned because one or more allocation decider returns a 'NO' decision", "weight" : 0.06666675, ⑨ "decisions" : [ { ⑩ "decider" : "filter", "decision" : "NO", "explanation" : "node does not match index include filters [foo:\"bar\"]" } ] }, "Qc6VL8c5RWaw1qXZ0Rg57g" : { "node_name" : "bGG90GE", "node_attributes" : { "bar" : "baz", "foo" : "bar" }, "store" : { "shard_copy" : "AVAILABLE" }, "final_decision" : "NO", "final_explanation" : "the shard cannot be assigned because one or more allocation decider returns a 'NO' decision", "weight" : -1.3833332, "decisions" : [ { "decider" : "same_shard", "decision" : "NO", "explanation" : "the shard cannot be allocated on the same node id [Qc6VL8c5RWaw1qXZ0Rg57g] on which it already exists" } ] }, "PzdyMZGXQdGhqTJHF_hGgA" : { "node_name" : "DKDM97B", "node_attributes" : { }, "store" : { "shard_copy" : "NONE" }, "final_decision" : "NO", "final_explanation" : "the shard cannot be assigned because one or more allocation decider returns a 'NO' decision", "weight" : 2.3166666, "decisions" : [ { "decider" : "filter", "decision" : "NO", "explanation" : "node does not match index include filters [foo:\"bar\"]" } ] } } } ``` | 编号 | 描述 | | --- | --- | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-1) | Whether the shard is assigned or unassigned | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-2) | Whether information about the shard is still being fetched | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-3) | Reason for the shard originally becoming unassigned | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-4) | Configured delay before the shard can be allocated | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-5) | Remaining delay before the shard can be allocated | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-6) | User-added attributes the node has | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-7) | The shard copy information for this node and error (if applicable) | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-8) | Final decision and explanation of whether the shard can be allocated to this node | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-9) | Weight for how much the allocator would like to allocate the shard to this node | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO138-10) | List of node decisions factoring into final decision about the shard | 对于一个已经分配的分片来说，输出与下面相似 :  ``` { "shard" : { "index" : "only-foo", "index_uuid" : "KnW0-zELRs6PK84l0r38ZA", "id" : 0, "primary" : true }, "assigned" : true, "assigned_node_id" : "Qc6VL8c5RWaw1qXZ0Rg57g", ① "shard_state_fetch_pending": false, "allocation_delay_ms" : 0, "remaining_delay_ms" : 0, "nodes" : { "V-Spi0AyRZ6ZvKbaI3691w" : { "node_name" : "bGG90GE", "node_attributes" : { "bar" : "baz" }, "store" : { "shard_copy" : "NONE" }, "final_decision" : "NO", "final_explanation" : "the shard cannot be assigned because one or more allocation decider returns a 'NO' decision", "weight" : 1.4499999, "decisions" : [ { "decider" : "filter", "decision" : "NO", "explanation" : "node does not match index include filters [foo:\"bar\"]" } ] }, "Qc6VL8c5RWaw1qXZ0Rg57g" : { "node_name" : "I8hydUG", "node_attributes" : { "bar" : "baz", "foo" : "bar" }, "store" : { "shard_copy" : "AVAILABLE" }, "final_decision" : "ALREADY_ASSIGNED", ② "final_explanation" : "the shard is already assigned to this node", "weight" : 0.0, "decisions" : [ { "decider" : "same_shard", "decision" : "NO", "explanation" : "the shard cannot be allocated on the same node id [Qc6VL8c5RWaw1qXZ0Rg57g] on which it already exists" } ] }, "PzdyMZGXQdGhqTJHF_hGgA" : { "node_name" : "H5dfFeA", "node_attributes" : { }, "store" : { "shard_copy" : "NONE" }, "final_decision" : "NO", "final_explanation" : "the shard cannot be assigned because one or more allocation decider returns a 'NO' decision", "weight" : 3.6999998, "decisions" : [ { "decider" : "filter", "decision" : "NO", "explanation" : "node does not match index include filters [foo:\"bar\"]" } ] } } } ``` | 编号 | 描述 | | --- | --- | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO139-1) | Node the shard is currently assigned to | | [](https://www.elastic.co/guide/en/elasticsearch/reference/5.0/cluster-allocation-explain.html#CO139-2) | The decision is "ALREADY_ASSIGNED" because the shard is currently assigned to this node | 您也可以让 **Elasticsearch explain** 第一个未分配分片的分配情况，它可以通过发送一个空的 **body** 来找到，例如 :  ``` $ curl -XGET 'http://localhost:9200/_cluster/allocation/explain' ``` 如果您想要去包含所有的那些我们考虑到的最终的决策的决定，该 _**`include_yes_decisions` **_参数将返回所有的决策 :  ``` $ curl -XGET 'http://localhost:9200/_cluster/allocation/explain?include_yes_decisions=true' ``` 此外，通过设置 _**`include_disk_info`**_参数为 _**true**_，您可以返回通过集群信息服务返回收集到的信息，包括硬盘使用和分配大小。 ``` $ curl -XGET 'http://localhost:9200/_cluster/allocation/explain?include_disk_info=true' ```