Analzer.pptx

이제 각 단계를 살펴보자.

$ curl -XPUT 'localhost:9200/_cluster/settings?pretty=true' -d
{
    "transient" : {
        "cluster.routing.allocation.enable" : "none"
    }
}

3) 노드를 shutdown 한다.     <----- es5.5에서는 _shutdown 명령어가 _shutdown API has been removed

                                            (https://www.elastic.co/guide/en/elasticsearch/reference/5.5/cluster-nodes-shutdown.html)

$ curl -XPOST 'localhost:9200/_cluster/nodes/_local/_shutdown'

자, 2)번에서 allocation을 disable 했다. 이러한 설정상태에서 node를 shutdown하면, 아래와같이 shutdown한 node에 있던 shard들은 재배치 되지 않고 'Unassinged' 상태로 남아있다.

바로 위에 언급했던 '불필요한 I/O작업'을 피할 수 있는것이다.

4) 해야하는 작업을 한다 (유지보수/upgrade)

5) node를 다시 구동하고, 클러스터에 합류하는지 확인한다.

$ sudo service elasticsearch start
 
Starting Elasticsearch...
Waiting for Elasticsearch......
running: PID:25374

6) 2번에서 disable했던 allocation 옵션을 다시 enable한다.

$ curl -XPUT 'localhost:9200/_cluster/settings?pretty=true' -d
{
    "transient" : {
        "cluster.routing.allocation.enable" : "all"
    }
}

자 이렇게 되면 'Unassigned' 상태에있던 shard들이 아래와 같이 재배치 될것이다.

3. 결론

https://www.elastic.co/guide/en/elasticsearch/guide/2.x/index.html

Elasticsearch: The Definitive Guide

If you would like to purchase an eBook or printed version of this book once it is complete, you can do so from O'Reilly Media: Buy this book from O'Reilly Media

만약 당신이 eBook을 구매하기 원하거나 또는 당신은 이것이 완벽할 때 이 book의 버전을 출력했다면, 당신은 O'Reilly Media 부터 그렇게 할 수 있다: Buy this book from O'Reilly Media

We welcome feedback – if you spot any errors or would like to suggest improvements, please open an issue on the GitHub repo.

우리는 feedback을 환영하다. 만약 당신이 어떤 에러들의 지점 또는 향상들에 대한 제한을 원한다면, the GitHub repo에 이슈를 open해 주세요.

Getting Started

Elasticsearch is a real-time distributed search and analytics engine. It allows you to explore your data at a speed and at a scale never before possible. It is used for full-text search, structured search, analytics, and all three in combination:

Elasticsearch 는 search와 분석이 분배된 real-time 엔진이다. 이것은 당신에게 당신의 데이터를 빠르고 이전에는 불가능했던 규모를 분석하는것을 허용한다. 이것은 full-text search, 구조화된 검색, 분석, 그리고 combination내에 3가지 전부를 위해 사용된다.

But Elasticsearch is not just for mega-corporations. It has enabled many startups like Datadog and Klout to prototype ideas and to turn them into scalable solutions. Elasticsearch can run on your laptop, or scale out to hundreds of servers and petabytes of data.

그러나 Elasticsearch 단지 mega-corporations을 위한건 아니다. 이것은 현재 이미 Datadog, Klout와 같은 prototype ideas 와  많은 startup들이 이용했다.

No individual part of Elasticsearch is new or revolutionary. Full-text search has been done before, as have analytics systems and distributed databases. The revolution is the combination of these individually useful parts into a single, coherent, real-time application. It has a low barrier to entry for the new user, but can keep pace with you as your skills and needs grow.

If you are picking up this book, it is because you have data, and there is no point in having data unless you plan to do something with it.

Unfortunately, most databases are astonishingly inept at extracting actionable knowledge from your data. Sure, they can filter by timestamp or exact values, but can they perform full-text search, handle synonyms, and score documents by relevance? Can they generate analytics and aggregations from the same data? Most important, can they do this in real time without big batch-processing jobs?

This is what sets Elasticsearch apart: Elasticsearch encourages you to explore and utilize your data, rather than letting it rot in a warehouse because it is too difficult to query.

Elasticsearch is your new best friend.