Shulou(Shulou.com)06/02 Report--

今天就跟大家聊聊有关Elasticsearch运维实战常用命令有哪些，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。

1、集群状态非绿排查清单1.1 集群状态的含义红色：至少一个主分片未分配成功;黄色：至少一个副本分片未分配成功;绿色：全部主&副本都分配成功。1.2 排查实战1.2.1 查看集群状态GET _cluster/health

返回状态举例："status" : "red", 红色，至少一个主分片未分配成功。

1.2.2 到底哪个节点出现了红色或者黄色问题呢？GET _cluster/health?level=indices

如下的方式，更明快直接

GET /_cat/indices?v&health=yellow

GET /_cat/indices?v&health=red

找到对应的索引。

1.2.3 到底索引的哪个分片出现了红色或者黄色问题呢？GET _cluster/health?level=shards

1.2.4 到底什么原因导致了集群变成红色或者黄色呢？GET _cluster/allocation/explain

返回核心信息解读举例：

"current_state" : "unassigned",--未分配

"unassigned_info" : {

"reason" : "INDEX_CREATED",--原因，索引创建阶段

"at" : "2020-01-29T07:32:39.041Z",

"last_allocation_status" : "no"

},

"explanation" : """node does not match index setting [index.routing.allocation.require] filters [box_type:"hot"]"""

}

根本原因，shard分片与节点过滤类型不一致 到此，找到了根本原因，也就知道了对应解决方案。

1.3 扩展思考：类似 "current_state" : "unassigned",--未分配 还有哪些？

实战：

GET _cat/shards?h=index,shard,prirep,state,unassigned.reason

官网：https://www.elastic.co/guide/en/elasticsearch/reference/7.2/cat-shards.html

未分配状态及原因解读：

（1）INDEX_CREATED

Unassigned as a result of an API creation of an index.

（2）CLUSTER_RECOVERED

Unassigned as a result of a full cluster recovery.

（3）INDEX_REOPENED

Unassigned as a result of opening a closed index.

（4）DANGLING_INDEX_IMPORTED

Unassigned as a result of importing a dangling index.

（5）NEW_INDEX_RESTORED

Unassigned as a result of restoring into a new index.

（6）EXISTING_INDEX_RESTORED

Unassigned as a result of restoring into a closed index.

（7）REPLICA_ADDED

Unassigned as a result of explicit addition of a replica.

（8）ALLOCATION_FAILED

Unassigned as a result of a failed allocation of the shard.

（9）NODE_LEFT

Unassigned as a result of the node hosting it leaving the cluster.

（10）REROUTE_CANCELLED

Unassigned as a result of explicit cancel reroute command.

（11）REINITIALIZED

When a shard moves from started back to initializing, for example, with shadow replicas.

（12）REALLOCATED_REPLICA

A better replica location is identified and causes the existing replica allocation to be cancelled.

2、节点间分片移动

适用场景：手动移动分配分片。将启动的分片从一个节点移动到另一节点。

POST /_cluster/reroute

{

"commands": [

{

"move": {

"index": "indexname",

"shard": 1,

"from_node": "nodename",

"to_node": "nodename"

}

}

]

}

3、集群节点优雅下线

适用场景：保证集群颜色绿色的前提下，将某个节点优雅下线。

PUT /_cluster/settings

{

"transient": {

"cluster.routing.allocation.exclude._ip": "122.5.3.55"

}

}

4、强制刷新

适用场景：刷新索引是确保当前仅存储在事务日志中的所有数据也永久存储在Lucene索引中。

POST /_flush

注意：这和 7.6 版本之前的同步刷新（未来8版本+会废弃同步刷新）一致。

POST /_flush/synced

5、更改并发分片的数量以平衡集群

适用场景：

控制在集群范围内允许多少并发分片重新平衡。默认值为2。

PUT /_cluster/settings

{

"transient": {

"cluster.routing.allocation.cluster_concurrent_rebalance": 2

}

}

6、更改每个节点同时恢复的分片数量

适用场景：

如果节点已从集群断开连接，则其所有分片将都变为未分配状态。经过一定的延迟后，分片将分配到其他位置。每个节点要恢复的并发分片数由该设置确定。

PUT /_cluster/settings

{

"transient": {

"cluster.routing.allocation.node_concurrent_recoveries": 6

}

}

7、调整恢复速度

适用场景：

为了避免集群过载，Elasticsearch限制了分配给恢复的速度。你可以仔细更改该设置，以使其恢复更快。

如果此值调的太高，则正在进行的恢复可能会消耗过多的带宽和其他资源，这可能会使集群不稳定。

PUT /_cluster/settings

{

"transient": {

"indices.recovery.max_bytes_per_sec": "80mb"

}

}

8、清除节点上的缓存

适用场景：如果节点达到较高的JVM值，则可以在节点级别上调用该API 以使 Elasticsearch 清理缓存。

这会降低性能，但可以使你摆脱OOM（内存不足）的困扰。

POST /_cache/clear

9、调整断路器

适用场景：为了避免在Elasticsearch中进入OOM，可以调整断路器上的设置。这将限制搜索内存，并丢弃所有估计消耗比所需级别更多的内存的搜索。

注意：这是一个非常精密的设置，你需要仔细校准。

PUT /_cluster/settings

{

"persistent": {

"indices.breaker.total.limit": "40%"

}

}

10、集群迁移

适用场景：集群数据迁移、索引数据迁移等。

方案一、 针对索引部分或者全部数据，reindex

POST _reindex

{

"source": {

"index": "my-index-000001"

},

"dest": {

"index": "my-new-index-000001"

}

}

Solution 2: Migrate index or cluster elasticdumpelasticsearch-migration with the help of third-party tools

Tool essence: scroll + bulk implementation.

Cluster Data Backup and Recovery

Applicable scenarios: high-availability business scenarios, regular incremental, full-volume data backup for emergency needs.

PUT /_snapshot/my_backup/snapshot_hamlet_index? wait_for_completion=true

{

"indices": "hamlet_*",

"ignore_unavailable": true,

"include_global_state": false,

"metadata": {

"taken_by": "mingyi",

"taken_because": "backup before upgrading"

}

}

POST /_snapshot/my_backup/snapshot_hamlet_index/_restore

After reading the above content, do you have any further understanding of Elasticsearch's common operation and maintenance commands? If you still want to know more knowledge or related content, please pay attention to the industry information channel, thank you for your support.

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