MongoDB的集群模式 – Replica Set

星哥玩云

发布于 2022-08-18 14:23:53

9190

发布于 2022-08-18 14:23:53

文章被收录于专栏：开源部署

一、Replica Set 集群分为两种架构：

奇数个节点构成Replica Set，所有节点拥有数据集。最小架构: 1个Primary节点，2个Secondary节点

偶数个节点 + 一个仲裁节点构成的Replica Set，节点拥有数据集，仲裁节点仅参与仲裁选举出Primary节点。最小架构：1个Primary节点，1个Secondary节点，1个Arbiter节点

接下来就以3台服务器为例，部署具有仲裁的框架。

IP地址	操作系统版本	MongoDB版本	端口	功能
10.10.18.10	CentOS7.5	4.0	27017	Primary
10.10.18.11	Centos7.5	4.0	27017	Secondary
10.10.18.12	Centos7.5	4.0	27017	Arbiter

二、安装部署（请访问 "MongoDB安装"）https://www.linuxidc.com/Linux/2019-07/159249.htm

Primary的配置文件：

systemLog:
   destination: file
   path: "/data/mongodb/log/mongod.log"
   logAppend: true
storage:
   dbPath: "/data/mongodb/data"
   journal:
      enabled: true
   wiredTiger:
      engineConfig:
        cacheSizeGB: 2
processManagement:
   fork: true
   pidFilePath: "/data/mongodb/pid/m.pid"
net:
   bindIp: 10.10.18.10
   port: 27017

replication:
   replSetName: "rs0"

Secondary的配置文件

systemLog:
   destination: file
   path: "/data/mongodb/log/mongod.log"
   logAppend: true
storage:
   dbPath: "/data/mongodb/data"
   journal:
      enabled: true
   wiredTiger:
      engineConfig:
        cacheSizeGB: 2
processManagement:
   fork: true
   pidFilePath: "/data/mongodb/pid/m.pid"
net:
   bindIp: 10.10.18.11
   port: 27017
replication:
   replSetName: "rs0"

Arbiter的配置文件

systemLog:
   destination: file
   path: "/data/mongodb/log/mongod.log"
   logAppend: true
storage:
   dbPath: "/data/mongodb/data"
   journal:
      enabled: true
   wiredTiger:
      engineConfig:
        cacheSizeGB: 2
processManagement:
   fork: true
   pidFilePath: "/data/mongodb/pid/m.pid"
net:
   bindIp: 10.10.18.12
   port: 27017
replication:
   replSetName: "rs0"

启动三台服务器上的mongdb

mongod -f /data/mongodb/mongod.conf

关闭进程

 mongod -f /data/mongodb/mongod.conf --shutdown

三、配置Replica Set

登录三台服务器中任意一台，登录mongo（如果报错就将配置文件中：security 内容暂时先去掉）

mongo --host 10.10.18.10

>cfg={ _id:"rs0",members:[{_id:0,host:'10.10.18.10:27017',priority:1},{_id:1,host:'10.10.18.11:27017',priority:1},{_id:2,host:'10.10.18.12:27017',arbiterOnly:true}] };

>rs.initiate(cfg)

查看Replica Set配置

> rs.conf()

{ "_id" : "rs0", "version" : 1, "protocolVersion" : NumberLong(1), "writeConcernMajorityJournalDefault" : true, "members" : [ { "_id" : 0, "host" : "10.10.18.10:27017", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : {

}, "slaveDelay" : NumberLong(0), "votes" : 1 }, { "_id" : 1, "host" : "10.10.18.11:27017", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : {

}, "slaveDelay" : NumberLong(0), "votes" : 1 }, { "_id" : 2, "host" : "10.10.18.12:27017", "arbiterOnly" : true, "buildIndexes" : true, "hidden" : false, "priority" : 0, "tags" : {

}, "slaveDelay" : NumberLong(0), "votes" : 1 } ], "settings" : { "chainingAllowed" : true, "heartbeatIntervalMillis" : 2000, "heartbeatTimeoutSecs" : 10, "electionTimeoutMillis" : 10000, "catchUpTimeoutMillis" : -1, "catchUpTakeoverDelayMillis" : 30000, "getLastErrorModes" : {

}, "getLastErrorDefaults" : { "w" : 1, "wtimeout" : 0 }, "replicaSetId" : ObjectId("5cff76e5e57e23a5bc7054e2") } }

四、验证Replica Set

在Primary中插入数据

rs0:PRIMARY>  show dbs
admin   0.000GB
config  0.000GB
local   0.000GB
rs0:PRIMARY> db.users.insertOne(
... {
... name:"sue",
... age: 26,
... status:"pending"
... })
{
        "acknowledged" : true,
        "insertedId" : ObjectId("5cff79e8993e70290a081d04")
}

rs0:PRIMARY> db.users.find() { "_id" : ObjectId("5cff79e8993e70290a081d04"), "name" : "sue", "age" : 26, "status" : "pending" }

在Secondary中，默认是不允许读

rs0:SECONDARY> db.users.find()
Error: error: {
        "operationTime" : Timestamp(1560247181, 1),
        "ok" : 0,
        "errmsg" : "not master and slaveOk=false",
        "code" : 13435,
        "codeName" : "NotMasterNoSlaveOk",
        "$clusterTime" : {
                "clusterTime" : Timestamp(1560247181, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
}

五、创建用户 https://www.linuxidc.com/Linux/2019-07/159238.htm

六、故障模拟

停止Primary上的mongo进程，在Secondary上登录mongo查看

mongo --host 10.10.18.11


rs0:PRIMARY> db.users.find()
{ "_id" : ObjectId("5cff79e8993e70290a081d04"), "name" : "sue", "age" : 26, "status" : "pending" }

发现原Secondary变成Primary，并且可以进行查询。

开启原Primary服务器上的mongo进程，该服务器变成了Secondary。

七、数据备份和恢复

mongodump从MongoDB中读取数据，保存为BSON文件，mongorestore读取BSON文件恢复到MongoDB中。适用于小型MongoDB的备份和恢复。

mongodump备份的时候只备份MongoDB中的文档，使用mongorestore恢复之后需要重建索引

mongodump --host 10.10.18.11 --port 27017 --username myUserAdmin --password abc123 --gzip --out /data/mongobak/$(date +%F)

注：--oplog  表示备份的时候oplog.bson文件，存放在dump开始 到 dump结束之间所有的oplog。

根据前面的备份恢复到一个新的Replica Set集群中其中一台服务器上。

恢复

恢复的过程中，不要启用认证。否则在将其他机器加入到Replica Set集群中来的时候，会出现无法认证的问题。

1、首先在一台服务器上开启一个干净mongo服务（无任何数据），做为 Primary

mongd.conf配置文件内容

systemLog:
   destination: file
   path: "/data/mongodb/log/mongod.log"
   logAppend: true
storage:
   dbPath: "/data/mongodb/data"
   journal:
      enabled: true
   wiredTiger:
      engineConfig:
        cacheSizeGB: 2
processManagement:
   fork: true
   pidFilePath: "/data/mongodb/pid/mongod.pid"
net:
   bindIp: 10.10.18.10
   port: 27017
replication:
   replSetName: "rs0"

2、开启mongod服务

/data/mongodb/bin/mongod -f /data/mongodb/mongod.conf

3、创建单个Replica Set

登录mongo，然后创建单个Replica Set

mongo --host 10.10.18.10
> cfg={_id:"rs0",members:[{_id:0,host:'10.10.18.10:27017',priority:1}]}

> rs.initiate(cfg)

创建结果：

{ "ok" : 1, "operationTime" : Timestamp(1560394449, 1), "$clusterTime" : { "clusterTime" : Timestamp(1560394449, 1), "signature" : { "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="), "keyId" : NumberLong(0) } } }

创建好了之后，就可以查看当前的数据库

rs0:SECONDARY> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB

可以发现，目前就三个基本的数据库。

4、恢复数据

mongorestore --host 10.10.18.10 --port 27017 --gzip /data/mongobak/2019-06-12

结果

2019-06-13T10:55:33.817+0800 preparing collections to restore from 2019-06-13T10:55:33.829+0800 reading metadata for admin.test from /data/mongobak/2019-06-12/admin/test.metadata.json.gz 2019-06-13T10:55:33.832+0800 reading metadata for test.users from /data/mongobak/2019-06-12/test/users.metadata.json.gz 2019-06-13T10:55:33.834+0800 reading metadata for reporting.reporting from /data/mongobak/2019-06-12/reporting/reporting.metadata.json.gz 2019-06-13T10:55:33.841+0800 reading metadata for admin.reporting from /data/mongobak/2019-06-12/admin/reporting.metadata.json.gz 2019-06-13T10:55:33.861+0800 restoring test.users from /data/mongobak/2019-06-12/test/users.bson.gz 2019-06-13T10:55:34.085+0800 restoring admin.test from /data/mongobak/2019-06-12/admin/test.bson.gz 2019-06-13T10:55:34.123+0800 no indexes to restore 2019-06-13T10:55:34.123+0800 finished restoring test.users (1 document) 2019-06-13T10:55:34.123+0800 restoring admin.reporting from /data/mongobak/2019-06-12/admin/reporting.bson.gz 2019-06-13T10:55:34.175+0800 restoring reporting.reporting from /data/mongobak/2019-06-12/reporting/reporting.bson.gz 2019-06-13T10:55:34.230+0800 no indexes to restore 2019-06-13T10:55:34.230+0800 finished restoring admin.test (2 documents) 2019-06-13T10:55:34.233+0800 no indexes to restore 2019-06-13T10:55:34.233+0800 finished restoring reporting.reporting (1 document) 2019-06-13T10:55:34.234+0800 no indexes to restore 2019-06-13T10:55:34.234+0800 finished restoring admin.reporting (1 document) 2019-06-13T10:55:34.234+0800 restoring users from /data/mongobak/2019-06-12/admin/system.users.bson.gz 2019-06-13T10:55:34.312+0800 done

恢复完成，在登录mongo查看，恢复数据库的情况。

rs0:PRIMARY> show dbs admin 0.000GB config 0.000GB local 0.000GB reporting 0.000GB test 0.000GB rs0:PRIMARY> use test switched to db test rs0:PRIMARY> show collections users rs0:PRIMARY> db.users.find() { "_id" : ObjectId("5cff79e8993e70290a081d04"), "name" : "sue", "age" : 26, "status" : "pending" }

可以看出之前的记录已经恢复了。

注意：如果备份时，MongoDB是拥有用户名和密码才能进行登录的，在恢复之后，用户名和密码也是可以使用的。如果需要在使用认证登录，需要将下面信息添加的配置文件mongod.conf：

security:
   keyFile: "/data/mongodb/keyfile"
   authorization: "enabled"

然后重启mongo服务。

5、关闭刚恢复的MongoDB，将数据目录同步到另一台服务器上，作为Secondary

通过之前，确认该台服务器上的mongo是无任何数据。将Primary服务上的 /data/mongodb/data 同步到 Secondary服务器上 /data/mongodb/data

6、依次开启Primary、Secondary、Arbiter的mongo服务

7、在Primary服务器上，将Secondary、Arbiter加入到Replica Set集群中来

查看当前Replica Set集群的配置

rs0:PRIMARY> rs.conf()
{
        "_id" : "rs0",
        "version" : 1,
        "protocolVersion" : NumberLong(1),
        "writeConcernMajorityJournalDefault" : true,
        "members" : [
                {
                        "_id" : 0,
                        "host" : "10.10.18.10:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 1,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                }
        ],
        "settings" : {
                "chainingAllowed" : true,
                "heartbeatIntervalMillis" : 2000,
                "heartbeatTimeoutSecs" : 10,
                "electionTimeoutMillis" : 10000,
                "catchUpTimeoutMillis" : -1,
                "catchUpTakeoverDelayMillis" : 30000,
                "getLastErrorModes" : {

                },
                "getLastErrorDefaults" : {
                        "w" : 1,
                        "wtimeout" : 0
                },
                "replicaSetId" : ObjectId("5d01bad15dfd3f294d147b36")
        }
}

可以看到当前Replica Set集群中就一台服务器

将Secondary、Arbiter加入到Replica Set集群中

rs0:PRIMARY> rs.add(
... {
... _id: 1,
... host:'10.10.18.11:27017',
... priority:1
... }
... )
{
        "ok" : 1,
        "operationTime" : Timestamp(1560397822, 1),
        "$clusterTime" : {
                "clusterTime" : Timestamp(1560397822, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
}
rs0:PRIMARY> rs.add(
... {
... _id: 2,
... host:'10.10.18.12:27017',
... arbiterOnly:true
... }
... )
{
        "ok" : 1,
        "operationTime" : Timestamp(1560397830, 1),
        "$clusterTime" : {
                "clusterTime" : Timestamp(1560397830, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }

再次查看状态：

rs0:PRIMARY> rs.conf()
{
        "_id" : "rs0",
        "version" : 3,
        "protocolVersion" : NumberLong(1),
        "writeConcernMajorityJournalDefault" : true,
        "members" : [
                {
                        "_id" : 0,
                        "host" : "10.10.18.10:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 1,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                },
                {
                        "_id" : 1,
                        "host" : "10.10.18.11:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 1,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                },
                {
                        "_id" : 2,
                        "host" : "10.10.18.12:27017",
                        "arbiterOnly" : true,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 0,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                }
        ],
        "settings" : {
                "chainingAllowed" : true,
                "heartbeatIntervalMillis" : 2000,
                "heartbeatTimeoutSecs" : 10,
                "electionTimeoutMillis" : 10000,
                "catchUpTimeoutMillis" : -1,
                "catchUpTakeoverDelayMillis" : 30000,
                "getLastErrorModes" : {

                },
                "getLastErrorDefaults" : {
                        "w" : 1,
                        "wtimeout" : 0
                },
                "replicaSetId" : ObjectId("5d01bad15dfd3f294d147b36")
        }
}

加入成功。

开启认证访问

在三台服务器的配置文件中添加：

security:
   keyFile: "/data/mongodb/keyfile"
   authorization: "enabled"

然后依次关闭：Arbiter Secondary Primary

依次开启：Primary Secondary Arbiter

security:
   keyFile: "/data/mongodb/keyfile"
   authorization: "enabled"

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