[MongoDB] ReplicaSet 환경 구성하기 (1)

몽고디비에서 Replica Set 환경을 구성해 본다. ReplicaSet을 하나의 Shard로 만들어서 여러개의 Shard가 구성되면 하기와 같이 routing은 mongos가 해준다

1. Replica Set 만들기

  - 옵션 : --replSet 

  - 디렉토리 만들어 놓기 : db1, db2, db3을 미리 만들어 놓는다

mongodb_2.4.5> mongod --replSet dowonSet --port  20000  -dbpath /mongodb_2.4.5/db1
Sat Jul 27 14:11:58.007 [initandlisten] MongoDB starting : pid=71010 port=20000 dbpath=/mongodb_2.4.5/db1 64-bit host=nulpulum-mac-13-retina.local
Sat Jul 27 14:11:58.299 [websvr] admin web console waiting for connections on port 21000
Sat Jul 27 14:11:58.300 [initandlisten] waiting for connections on port 20000
Sat Jul 27 14:12:08.302 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)

mongodb_2.4.5> mongod --replSet dowonSet --port  30000  -dbpath /mongodb_2.4.5/db2
Sat Jul 27 14:32:08.934 [initandlisten] MongoDB starting : pid=71062 port=30000 dbpath=/mongodb_2.4.5/db2 64-bit host=nulpulum-mac-13-retina.local

/mongodb_2.4.5> mongod --replSet dowonSet --port  40000  -dbpath /mongodb_2.4.5/db3
Sat Jul 27 14:32:16.317 [initandlisten] MongoDB starting : pid=71063 port=40000 dbpath=/mongodb_2.4.5/db3 64-bit host=nulpulum-mac-13-retina.local

2. Replica Set 환경설정하기

  - mongo REPL 로 연결

  - config 환경 구성

/mongodb_2.4.5> mongo localhost:20000
MongoDB shell version: 2.4.5
connecting to: localhost:20000/test
> var config={_id:'dowonSet', members:[{_id:0, host:'localhost:20000'}, {_id:1, host:'localhost:30000'}, {_id:2, host:'localhost:40000'}] };

///////////// Replica set help 보기

> rs.help();
    rs.status()                         { replSetGetStatus : 1 } checks repl set status
    rs.initiate()                         { replSetInitiate : null } initiates set with default settings
    rs.initiate(cfg)                   { replSetInitiate : cfg } initiates set with configuration cfg
    rs.conf()                           get the current configuration object from local.system.replset
    rs.reconfig(cfg)                  updates the configuration of a running replica set with cfg (disconnects)
    rs.add(hostportstr)             add a new member to the set with default attributes (disconnects)
    rs.add(membercfgobj)        add a new member to the set with extra attributes (disconnects)
    rs.addArb(hostportstr)        add a new member which is arbiterOnly:true (disconnects)
    rs.stepDown([secs])          step down as primary (momentarily) (disconnects)
    rs.syncFrom(hostportstr)    make a secondary to sync from the given member
    rs.freeze(secs)                  make a node ineligible to become primary for the time specified
    rs.remove(hostportstr)       remove a host from the replica set (disconnects)
    rs.slaveOk()                      shorthand for db.getMongo().setSlaveOk()

    db.isMaster()                     check who is primary
    db.printReplicationInfo()       check oplog size and time range

    reconfiguration helpers disconnect from the database so the shell will display
    an error, even if the command succeeds.
    see also http://<mongod_host>:28017/_replSet for additional diagnostic info

///////////// 환경 적용하기

> rs.initiate(config);
{
    "info" : "Config now saved locally.  Should come online in about a minute.",
    "ok" : 1
}

///////////// Enter를 치면 프롬프트가 변경되어 나온다

dowonSet:PRIMARY>
dowonSet:PRIMARY> show dbs
local    0.328125GB
dowonSet:PRIMARY> use dowonDB
switched to db dowonDB
dowonSet:PRIMARY> db
dowonDB
dowonSet:PRIMARY>

3. REPL 조작하기

  - PRIMARY에서 데이터 조작하기

dowonSet:PRIMARY> db.person.save({age:23, name:'youngsik', title:'hi'});
dowonSet:PRIMARY> show collections
person
system.indexes
dowonSet:PRIMARY> db.person.find();
{ "_id" : ObjectId("51f35c76076489dd83ccb46d"), "age" : 23, "name" : "youngsik", "title" : "hi" }

  - SECONDARY 들어가 보기 : PRIMARY가 다운되면 show collections에서 에러가 발생하지 않고 자신이 PRIMARY로 된다

    PRIMARY 1개 + SECONDARY 2개 + 여분 n개

/mongodb_2.4.5> mongo localhost:30000
MongoDB shell version: 2.4.5
connecting to: localhost:30000/test
dowonSet:SECONDARY> show dbs
dowonDB    0.203125GB
local    0.328125GB
test    (empty)
dowonSet:SECONDARY> use dowonDB
switched to db dowonDB
dowonSet:SECONDARY> db
dowonDB
dowonSet:SECONDARY> show collections
Sat Jul 27 14:42:38.244 JavaScript execution failed: error: { "$err" : "not master and slaveOk=false", "code" : 13435 } at src/mongo/shell/query.js:L128

///////////// 20000 번 포트의 mongod를 강제로 다운시켰을 때 : 40000 포트의 mongod가 PRIMARY가 된다

/mongodb_2.4.5> mongo localhost:40000
MongoDB shell version: 2.4.5
connecting to: localhost:40000/test
dowonSet:PRIMARY>
dowonSet:PRIMARY> use dowonDB
switched to db dowonDB
dowonSet:PRIMARY> show collections
person
system.indexes
dowonSet:PRIMARY> db.person.find();
{ "_id" : ObjectId("51f35c76076489dd83ccb46d"), "age" : 23, "name" : "youngsik", "title" : "hi" }

  - SECONDARY로 들어가서 show collections가 안될 경우 rs.slaveOk() 명령수행

/mongodb_2.4.5> mongo localhost:30000
MongoDB shell version: 2.4.5
connecting to: localhost:30000/test
dowonSet:SECONDARY>
dowonSet:SECONDARY> show dbs
dowonDB    0.203125GB
local    0.328125GB
test    (empty)
dowonSet:SECONDARY> use dowonDB
switched to db dowonDB
dowonSet:SECONDARY> db
dowonDB
dowonSet:SECONDARY> show collections
Sat Jul 27 14:48:38.663 JavaScript execution failed: error: { "$err" : "not master and slaveOk=false", "code" : 13435 } at src/mongo/shell/query.js:L128
dowonSet:SECONDARY> rs.slaveOk();
dowonSet:SECONDARY> show collections
person
system.indexes
dowonSet:SECONDARY> db.person.find();
{ "_id" : ObjectId("51f35c76076489dd83ccb46d"), "age" : 23, "name" : "youngsik", "title" : "hi" }

현재까지 Shard 1개를 만들었다. (구현되지 않는 것은 거짓말이다)

<참조>

  - 10gen Sharding 메뉴얼