分布式文档存储数据库之MongoDB副本集

时间 2020-11-11

标签 html node mysql linux web sql mongodb shell 数据库 api 栏目系统架构繁體版

原文原文链接

　　前文咱们聊到了mongodb的索引的相关做用和介绍以及索引的管理，回顾请参考http://www.javashuo.com/article/p-blejkthn-nu.html；今天咱们来聊下mongodb的副本集；html

　　一、什么是副本集？主要做用是什么？它是怎么工做的呢？node

　　所谓副本集是指服务于同一数据集的多个mongodb实例；这意味着在mongodb中数据集副本的数量能够是多个，每一个副本的数据都是同样的；副本的存在主要做用是对mongodb数据库中的数据作冗余备份和提升数据服务的可用性；在mongodb中对数据作冗余的方式有两种，一种是主从架构（master/slave），这种架构和mysql中的主从架构没有什么不一样，可是在mongodb中，主从架构的方式几乎没有人用，处于废弃的状态。。另一种是副本集(replica set)，副本集本质上也是主从架构的一种，它和咱们刚才说的主从架构，有一个显著的区别，副本集支持故障自动转移，不须要人工手动干预；所谓的故障自动转移是指当一个副本集中主节点因各类缘由宕机或者从节点在必定时间内没有收到主节点发送到心跳信息，此时就会触发从节点从新选举主节点的操做；在多个从节点中选举出来一个主节点之后，其余从节点可以自动指向新选举的主节点同步数据，从而完成此次故障转移；mysql

　　二、mongodb副本集架构linux

　　提示：对于mongodb中的副本集来讲，为了保证数据的一致性，一个副本集中只能有一个主节点，而且只有主节点才拥有读写权限，其余从节点都只有读权限；在mongodb的副本集中，主节点咱们叫作primary，从节点叫作secondary；web

　　三、副本集是经过什么来复制数据的呢？sql

　　我知道mysql的主从复制是经过主节点记录写操做到binlog中，从节点经过同步主节点的binlog，而后把同步的binlog在本地进行重放，从而实现数据同步；在mongodb中也是相似的操做，不一样的是在mongodb中主节点将写操做记录到oplog(操做日志)，各从节点经过复制主节点的oplog，在本地重放实现数据同步；oplog的做用和mysql中的binlog的做用很相似，都是用来记录写操做事件，都是用来同步数据；mongodb中的oplog是一个定容集合，所谓定容是指它的大小是固定的，它不会像binlog随日志的增多而逐渐变大；一般oplog咱们不人为指定其大小，默认就是占用所在文件系统空闲磁盘的5%；除了大小是不变的，它还有一个幂等的特色；所谓幂等就是无论在monogdb中执行多少次oplog中的操做，其最终的结果都是同样的；若是写操做日志把oplog写满了，它会从头覆盖以前的oplog，依次循环写oplog；mongodb

　　四、副本集是怎么完成故障转移的？shell

　　在前边咱们聊zookeeper时，聊到过度布式场景中的选举过程；mongodb的主节点故障之后，也是经过这种机制来完成选举；在mongodb的副本集中，主节点每隔两秒向各从节点发送心跳信息，各从节点经过检测主节点的心跳信息来断定主节点是否存活；若是在必定的时间范围内，从节点没有收到主节点发送到心跳信息，此时从节点会认为主节点挂了，从而触发主节点选举的操做；这个选举和zookeeper里的选举很相似，一般状况都是大于集群总票的一半一方能够表明集群正常工做；因此一般状况mongodb副本集都是基数个节点组成；固然mongodb中也能够是偶数节点（正常提供服务的节点），若是是偶数节点，一般会借助一个仲裁节点来完成选举；仲裁节点拥有选票，但不被选举成为主节点，也不拥有副本数据，同时它必需要可以检测主节点心跳；简单总结就是mongodb副本集是经过从节点检测主节点心跳来判断主节点是否存活，若是在必定时间范围内，没有检测到主节点的心跳信息，此时就会触发主节点选举操做，若是集群节点数量为偶数个，一般会借助仲裁节点来完成选举；从而实现完成故障自动转移；数据库

　　五、mongodb副本集中特殊类型节点分类api

　　0优先级节点：这种节点的特色是优先级为0，可参与选举，拥有副本数据，但不被选举成为主节点，可读不可写；这种节点咱们也叫冷备节点；一般用于异地容灾使用；

　　被隐藏的从节点：这种节点的特色是，可参与选举，拥有副本数据，但不被选举成为主节点，对客户端不可读写也不可见；一般用于同步同一副本集中的其余节点的不一样工做流的场景中；

　　延迟复制的从节点：这种节点的特色是，副本数据落后主节点一个时间窗口，也就说这种节点上的副本数据老是过时的；除此它可参与选举，不可被选举为主节点；主要用于特殊功用；好比在主节点上执行了一个删除操做，咱们能够在延迟复制的从节点上把数据找回；

　　arbiter节点：这种就是咱们说的仲裁节点，它可参与选举，不拥有副本数据，不被选举成为主节点，不可读写；主要做用是辅助断定主节点是否存活，辅助从节点完成选举，实现故障转移；

　　六、建立mongodb的副本集合

　　环境准备

主机名	ip地址
node01	192.168.0.41
node02	192.168.0.42
node03	192.168.0.43

　　在三个节点上分别作好时间同步，关闭selinux,关闭防火墙，主机名解析，有必要还能够作ssh互信。准备好基础环境之后，在三台server上配置mongodb的yum源

[root@node01 ~]# cat /etc/yum.repos.d/mongodb.repo 
[mongodb-org]
name = MongoDB Repository
baseurl = https://mirrors.aliyun.com/mongodb/yum/redhat/7/mongodb-org/4.4/x86_64/
gpgcheck = 1
enabled = 1
gpgkey = https://www.mongodb.org/static/pgp/server-4.4.asc
[root@node01 ~]# scp /etc/yum.repos.d/mongodb.repo node02:/etc/yum.repos.d/
mongodb.repo                                                                  100%  206    80.4KB/s   00:00    
[root@node01 ~]# scp /etc/yum.repos.d/mongodb.repo node03:/etc/yum.repos.d/
mongodb.repo                                                                  100%  206    88.9KB/s   00:00    
[root@node01 ~]#

　　安装mongodb-org

yum install -y mongodb-org

　　准备数据目录和存放日志的目录，并将其属主和属组更改成mongod用户

[root@node01 ~]# mkdir -pv /mongodb/{data,log} 
mkdir: created directory ‘/mongodb’
mkdir: created directory ‘/mongodb/data’
mkdir: created directory ‘/mongodb/log’
[root@node01 ~]# chown -R mongod.mongod /mongodb/
[root@node01 ~]# ll -d /mongodb/
drwxr-xr-x 4 mongod mongod 29 Nov 10 19:36 /mongodb/
[root@node01 ~]#

　　提示：以上需在三个节点都要作一遍；

　　配置mongodb

　　提示：主要配置replication，其中oplogSizeMB用来指定oplog的大小，默认不指定，其大小就是所在文件系统空闲磁盘的%5；replSetName用来指定副本集的名称，这个名称很是重要，主要用来标识不一样副本集；enableMajorityReadConcern用来指定是否开启mongodb周期性的作快照，并记录oplog的时间戳；

　　完整配置

[root@node01 ~]# cat /etc/mongod.conf
systemLog:
  destination: file
  logAppend: true
  path: /mongodb/log/mongod.log

storage:
  dbPath: /mongodb/data/
  journal:
    enabled: true

processManagement:
  fork: true  
  pidFilePath: /var/run/mongodb/mongod.pid
  timeZoneInfo: /usr/share/zoneinfo

net:
  port: 27017
  bindIp: 0.0.0.0

replication:
   oplogSizeMB: 2048
   replSetName: test_replset
   enableMajorityReadConcern: false



#security:

#operationProfiling:

#sharding:

## Enterprise-Only Options

#auditLog:

#snmp:
[root@node01 ~]#

View Code

　　复制配置文件到node02,node03

[root@node01 ~]# scp /etc/mongod.conf node02:/etc/
mongod.conf                                                                   100%  494   315.1KB/s   00:00    
[root@node01 ~]# scp /etc/mongod.conf node03:/etc/
mongod.conf                                                                   100%  494   351.6KB/s   00:00    
[root@node01 ~]#

　　启动服务

　　提示：请确保对应节点上的mongodb所监听的端口正常便可；

　　链接三个节点任意一个节点查看副本集状态

> 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([stepdownSecs, catchUpSecs])   step down as primary (disconnects)
        rs.syncFrom(hostportstr)                   make a secondary 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.secondaryOk()                               allow queries on secondary nodes

        rs.printReplicationInfo()                  check oplog size and time range
        rs.printSecondaryReplicationInfo()             check replica set members and replication lag
        db.isMaster()                              check who is primary

        reconfiguration helpers disconnect from the database so the shell will display
        an error, even if the command succeeds.
> rs.status() 
{
        "operationTime" : Timestamp(0, 0),
        "ok" : 0,
        "errmsg" : "no replset config has been received",
        "code" : 94,
        "codeName" : "NotYetInitialized",
        "$clusterTime" : {
                "clusterTime" : Timestamp(0, 0),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
}
>

　　提示：全部关于副本集的操做命令均可以使用rs.help()方法去查看帮助；其中rs.status()是用来查看副本集状态；这里显示没有副本集配置，其缘由是没有初始化副本集；

　　初始化副本集

> rs.initiate()
{
        "info2" : "no configuration specified. Using a default configuration for the set",
        "me" : "node01.test.org:27017",
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605010821, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605010821, 1)
}
test_replset:SECONDARY> rs.status()
{
        "set" : "test_replset",
        "date" : ISODate("2020-11-10T12:20:32.079Z"),
        "myState" : 1,
        "term" : NumberLong(1),
        "syncSourceHost" : "",
        "syncSourceId" : -1,
        "heartbeatIntervalMillis" : NumberLong(2000),
        "majorityVoteCount" : 1,
        "writeMajorityCount" : 1,
        "votingMembersCount" : 1,
        "writableVotingMembersCount" : 1,
        "optimes" : {
                "lastCommittedOpTime" : {
                        "ts" : Timestamp(1605010821, 8),
                        "t" : NumberLong(1)
                },
                "lastCommittedWallTime" : ISODate("2020-11-10T12:20:21.720Z"),
                "readConcernMajorityOpTime" : {
                        "ts" : Timestamp(1605010821, 8),
                        "t" : NumberLong(1)
                },
                "readConcernMajorityWallTime" : ISODate("2020-11-10T12:20:21.720Z"),
                "appliedOpTime" : {
                        "ts" : Timestamp(1605010821, 8),
                        "t" : NumberLong(1)
                },
                "durableOpTime" : {
                        "ts" : Timestamp(1605010821, 8),
                        "t" : NumberLong(1)
                },
                "lastAppliedWallTime" : ISODate("2020-11-10T12:20:21.720Z"),
                "lastDurableWallTime" : ISODate("2020-11-10T12:20:21.720Z")
        },
        "electionCandidateMetrics" : {
                "lastElectionReason" : "electionTimeout",
                "lastElectionDate" : ISODate("2020-11-10T12:20:21.632Z"),
                "electionTerm" : NumberLong(1),
                "lastCommittedOpTimeAtElection" : {
                        "ts" : Timestamp(0, 0),
                        "t" : NumberLong(-1)
                },
                "lastSeenOpTimeAtElection" : {
                        "ts" : Timestamp(1605010821, 1),
                        "t" : NumberLong(-1)
                },
                "numVotesNeeded" : 1,
                "priorityAtElection" : 1,
                "electionTimeoutMillis" : NumberLong(10000),
                "newTermStartDate" : ISODate("2020-11-10T12:20:21.694Z"),
                "wMajorityWriteAvailabilityDate" : ISODate("2020-11-10T12:20:21.719Z")
        },
        "members" : [
                {
                        "_id" : 0,
                        "name" : "node01.test.org:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 674,
                        "optime" : {
                                "ts" : Timestamp(1605010821, 8),
                                "t" : NumberLong(1)
                        },
                        "optimeDate" : ISODate("2020-11-10T12:20:21Z"),
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "Could not find member to sync from",
                        "electionTime" : Timestamp(1605010821, 2),
                        "electionDate" : ISODate("2020-11-10T12:20:21Z"),
                        "configVersion" : 1,
                        "configTerm" : 1,
                        "self" : true,
                        "lastHeartbeatMessage" : ""
                }
        ],
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605010821, 8),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605010821, 8)
}
test_replset:PRIMARY>

　　提示：初始化副本集之后，再次查看副本集状态，它告诉咱们有一个成员，其主机名为node01.test.org:27017,其health状态为1，stateStr为PRIMARY等等一堆信息；

　　查看副本集配置

test_replset:PRIMARY> rs.conf()
{
        "_id" : "test_replset",
        "version" : 1,
        "term" : 1,
        "protocolVersion" : NumberLong(1),
        "writeConcernMajorityJournalDefault" : true,
        "members" : [
                {
                        "_id" : 0,
                        "host" : "node01.test.org: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("5faa85853d5a2d8fdf8af85e")
        }
}
test_replset:PRIMARY>

　　提示：能够看到心跳时间间隔为2s，超时为10s,选举超时时长为10等等信息；

　　添加node02，node03节点到副本集成员

test_replset:PRIMARY> rs.add("node02")
{
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605011243, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605011243, 1)
}
test_replset:PRIMARY> rs.add("node03")
{
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605011250, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605011250, 1)
}
test_replset:PRIMARY> rs.status()
{
        "set" : "test_replset",
        "date" : ISODate("2020-11-10T12:27:45.849Z"),
        "myState" : 1,
        "term" : NumberLong(1),
        "syncSourceHost" : "",
        "syncSourceId" : -1,
        "heartbeatIntervalMillis" : NumberLong(2000),
        "majorityVoteCount" : 2,
        "writeMajorityCount" : 2,
        "votingMembersCount" : 3,
        "writableVotingMembersCount" : 3,
        "optimes" : {
                "lastCommittedOpTime" : {
                        "ts" : Timestamp(1605011261, 1),
                        "t" : NumberLong(1)
                },
                "lastCommittedWallTime" : ISODate("2020-11-10T12:27:41.873Z"),
                "readConcernMajorityOpTime" : {
                        "ts" : Timestamp(1605011261, 1),
                        "t" : NumberLong(1)
                },
                "readConcernMajorityWallTime" : ISODate("2020-11-10T12:27:41.873Z"),
                "appliedOpTime" : {
                        "ts" : Timestamp(1605011261, 1),
                        "t" : NumberLong(1)
                },
                "durableOpTime" : {
                        "ts" : Timestamp(1605011261, 1),
                        "t" : NumberLong(1)
                },
                "lastAppliedWallTime" : ISODate("2020-11-10T12:27:41.873Z"),
                "lastDurableWallTime" : ISODate("2020-11-10T12:27:41.873Z")
        },
        "electionCandidateMetrics" : {
                "lastElectionReason" : "electionTimeout",
                "lastElectionDate" : ISODate("2020-11-10T12:20:21.632Z"),
                "electionTerm" : NumberLong(1),
                "lastCommittedOpTimeAtElection" : {
                        "ts" : Timestamp(0, 0),
                        "t" : NumberLong(-1)
                },
                "lastSeenOpTimeAtElection" : {
                        "ts" : Timestamp(1605010821, 1),
                        "t" : NumberLong(-1)
                },
                "numVotesNeeded" : 1,
                "priorityAtElection" : 1,
                "electionTimeoutMillis" : NumberLong(10000),
                "newTermStartDate" : ISODate("2020-11-10T12:20:21.694Z"),
                "wMajorityWriteAvailabilityDate" : ISODate("2020-11-10T12:20:21.719Z")
        },
        "members" : [
                {
                        "_id" : 0,
                        "name" : "node01.test.org:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 1107,
                        "optime" : {
                                "ts" : Timestamp(1605011261, 1),
                                "t" : NumberLong(1)
                        },
                        "optimeDate" : ISODate("2020-11-10T12:27:41Z"),
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "",
                        "electionTime" : Timestamp(1605010821, 2),
                        "electionDate" : ISODate("2020-11-10T12:20:21Z"),
                        "configVersion" : 3,
                        "configTerm" : 1,
                        "self" : true,
                        "lastHeartbeatMessage" : ""
                },
                {
                        "_id" : 1,
                        "name" : "node02:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 21,
                        "optime" : {
                                "ts" : Timestamp(1605011261, 1),
                                "t" : NumberLong(1)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(1605011261, 1),
                                "t" : NumberLong(1)
                        },
                        "optimeDate" : ISODate("2020-11-10T12:27:41Z"),
                        "optimeDurableDate" : ISODate("2020-11-10T12:27:41Z"),
                        "lastHeartbeat" : ISODate("2020-11-10T12:27:44.967Z"),
                        "lastHeartbeatRecv" : ISODate("2020-11-10T12:27:43.983Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "node01.test.org:27017",
                        "syncSourceId" : 0,
                        "infoMessage" : "",
                        "configVersion" : 3,
                        "configTerm" : 1
                },
                {
                        "_id" : 2,
                        "name" : "node03:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 14,
                        "optime" : {
                                "ts" : Timestamp(1605011261, 1),
                                "t" : NumberLong(1)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(1605011261, 1),
                                "t" : NumberLong(1)
                        },
                        "optimeDate" : ISODate("2020-11-10T12:27:41Z"),
                        "optimeDurableDate" : ISODate("2020-11-10T12:27:41Z"),
                        "lastHeartbeat" : ISODate("2020-11-10T12:27:44.967Z"),
                        "lastHeartbeatRecv" : ISODate("2020-11-10T12:27:44.571Z"),
                        "pingMs" : NumberLong(1),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "node02:27017",
                        "syncSourceId" : 1,
                        "infoMessage" : "",
                        "configVersion" : 3,
                        "configTerm" : 1
                }
        ],
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605011261, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605011261, 1)
}
test_replset:PRIMARY>

　　提示：添加节点到副本成员使用rs.add（），括号里面写主机名，或者ip地址，若是对应节点监听端口不是27017，还须要写明端口；除此咱们也能够直接用一个子文档的形式，手动指定节点的各属性信息来添加节点到副本集成员；

　　到此副本集的配置就完成了，三个节点都添加到副本集；

　　验证：在主库上插入数据，看看从库是否均可以正常同步其数据呢？

　　在主节点插入数据

test_replset:PRIMARY> use students
switched to db students
test_replset:PRIMARY> db.student_info.insert({name:"tom",age:18,gender:"M"})
WriteResult({ "nInserted" : 1 })
test_replset:PRIMARY> db.student_info.find()
{ "_id" : ObjectId("5faa89297077300f4fc31d1c"), "name" : "tom", "age" : 18, "gender" : "M" }
test_replset:PRIMARY>

　　在从节点查看数据

test_replset:SECONDARY> show dbs
uncaught exception: Error: listDatabases failed:{
        "topologyVersion" : {
                "processId" : ObjectId("5faa83025f9218c5d19ea91b"),
                "counter" : NumberLong(4)
        },
        "operationTime" : Timestamp(1605011801, 1),
        "ok" : 0,
        "errmsg" : "not master and slaveOk=false",
        "code" : 13435,
        "codeName" : "NotMasterNoSlaveOk",
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605011801, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs/<@src/mongo/shell/mongo.js:147:19
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:99:12
shellHelper.show@src/mongo/shell/utils.js:937:13
shellHelper@src/mongo/shell/utils.js:819:15
@(shellhelp2):1:1
test_replset:SECONDARY>

　　提示：这里在从节点上无法查看数据，缘由是默认状况副本集配置好之后，要在从节点运行rs.secondaryOk()来告诉从节点已经配置好了，不然它会不容许咱们读，有点相似从节点为就绪的感受；

　　在从节点上运行rs.secondaryOk(),而后再次查看数据

test_replset:SECONDARY> rs.secondaryOk()  
test_replset:SECONDARY> show dbs
admin     0.000GB
config    0.000GB
local     0.000GB
students  0.000GB
test_replset:SECONDARY> use students
switched to db students
test_replset:SECONDARY> show collections
student_info
test_replset:SECONDARY> db.student_info.find().pretty()
{
        "_id" : ObjectId("5faa89297077300f4fc31d1c"),
        "name" : "tom",
        "age" : 18,
        "gender" : "M"
}
test_replset:SECONDARY>

　　提示：能够看到在secondary节点上可以查询到对应数据库中的对应collection中插入的数据；

　　验证：在从节点上插入数据，看看是否能插入成功？

test_replset:SECONDARY> db.student_info.insert({name:"jerry",age:19,gender:"M"})
WriteCommandError({
        "topologyVersion" : {
                "processId" : ObjectId("5faa831bde03c4ae108f0be4"),
                "counter" : NumberLong(3)
        },
        "operationTime" : Timestamp(1605012904, 1),
        "ok" : 0,
        "errmsg" : "not master",
        "code" : 10107,
        "codeName" : "NotMaster",
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605012904, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
})
test_replset:SECONDARY>

　　提示：咱们在从节点上插入数据，它提示咱们不是主节点，不容许插入数据；这说明副本集的从节点是不容许写；

　　验证：将主节点上的mongodb服务停掉，而后在其余两个节点上查看副本集状态，看看两个节点是否从新选举了master?

[root@node01 ~]# systemctl stop mongod.service 
[root@node01 ~]# ss -tnl
State      Recv-Q Send-Q           Local Address:Port                          Peer Address:Port              
LISTEN     0      128                          *:22                                       *:*                  
LISTEN     0      100                  127.0.0.1:25                                       *:*                  
LISTEN     0      128                         :::22                                      :::*                  
LISTEN     0      100                        ::1:25                                      :::*                  
[root@node01 ~]# mongo --host node02
MongoDB shell version v4.4.1
connecting to: mongodb://node02:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("90d60f76-fc95-44a8-bbf7-d927d5947331") }
MongoDB server version: 4.4.1
---
The server generated these startup warnings when booting: 
        2020-11-10T20:09:39.555+08:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
        2020-11-10T20:09:39.555+08:00: /sys/kernel/mm/transparent_hugepage/enabled is 'always'. We suggest setting it to 'never'
        2020-11-10T20:09:39.555+08:00: /sys/kernel/mm/transparent_hugepage/defrag is 'always'. We suggest setting it to 'never'
---
---
        Enable MongoDB's free cloud-based monitoring service, which will then receive and display
        metrics about your deployment (disk utilization, CPU, operation statistics, etc).

        The monitoring data will be available on a MongoDB website with a unique URL accessible to you
        and anyone you share the URL with. MongoDB may use this information to make product
        improvements and to suggest MongoDB products and deployment options to you.

        To enable free monitoring, run the following command: db.enableFreeMonitoring()
        To permanently disable this reminder, run the following command: db.disableFreeMonitoring()
---
test_replset:PRIMARY> rs.status()
{
        "set" : "test_replset",
        "date" : ISODate("2020-11-10T12:59:25.775Z"),
        "myState" : 1,
        "term" : NumberLong(2),
        "syncSourceHost" : "",
        "syncSourceId" : -1,
        "heartbeatIntervalMillis" : NumberLong(2000),
        "majorityVoteCount" : 2,
        "writeMajorityCount" : 2,
        "votingMembersCount" : 3,
        "writableVotingMembersCount" : 3,
        "optimes" : {
                "lastCommittedOpTime" : {
                        "ts" : Timestamp(1605013164, 1),
                        "t" : NumberLong(2)
                },
                "lastCommittedWallTime" : ISODate("2020-11-10T12:59:24.417Z"),
                "readConcernMajorityOpTime" : {
                        "ts" : Timestamp(1605013164, 1),
                        "t" : NumberLong(2)
                },
                "readConcernMajorityWallTime" : ISODate("2020-11-10T12:59:24.417Z"),
                "appliedOpTime" : {
                        "ts" : Timestamp(1605013164, 1),
                        "t" : NumberLong(2)
                },
                "durableOpTime" : {
                        "ts" : Timestamp(1605013164, 1),
                        "t" : NumberLong(2)
                },
                "lastAppliedWallTime" : ISODate("2020-11-10T12:59:24.417Z"),
                "lastDurableWallTime" : ISODate("2020-11-10T12:59:24.417Z")
        },
        "electionCandidateMetrics" : {
                "lastElectionReason" : "stepUpRequestSkipDryRun",
                "lastElectionDate" : ISODate("2020-11-10T12:58:34.398Z"),
                "electionTerm" : NumberLong(2),
                "lastCommittedOpTimeAtElection" : {
                        "ts" : Timestamp(1605013112, 1),
                        "t" : NumberLong(1)
                },
                "lastSeenOpTimeAtElection" : {
                        "ts" : Timestamp(1605013112, 1),
                        "t" : NumberLong(1)
                },
                "numVotesNeeded" : 2,
                "priorityAtElection" : 1,
                "electionTimeoutMillis" : NumberLong(10000),
                "priorPrimaryMemberId" : 0,
                "numCatchUpOps" : NumberLong(0),
                "newTermStartDate" : ISODate("2020-11-10T12:58:34.410Z"),
                "wMajorityWriteAvailabilityDate" : ISODate("2020-11-10T12:58:34.506Z")
        },
        "members" : [
                {
                        "_id" : 0,
                        "name" : "node01.test.org:27017",
                        "health" : 0,
                        "state" : 8,
                        "stateStr" : "(not reachable/healthy)",
                        "uptime" : 0,
                        "optime" : {
                                "ts" : Timestamp(0, 0),
                                "t" : NumberLong(-1)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(0, 0),
                                "t" : NumberLong(-1)
                        },
                        "optimeDate" : ISODate("1970-01-01T00:00:00Z"),
                        "optimeDurableDate" : ISODate("1970-01-01T00:00:00Z"),
                        "lastHeartbeat" : ISODate("2020-11-10T12:59:24.558Z"),
                        "lastHeartbeatRecv" : ISODate("2020-11-10T12:58:35.045Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "Error connecting to node01.test.org:27017 (192.168.0.41:27017) :: caused by :: Connection refused",
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "",
                        "configVersion" : 3,
                        "configTerm" : 1
                },
                {
                        "_id" : 1,
                        "name" : "node02:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 2987,
                        "optime" : {
                                "ts" : Timestamp(1605013164, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2020-11-10T12:59:24Z"),
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "",
                        "electionTime" : Timestamp(1605013114, 1),
                        "electionDate" : ISODate("2020-11-10T12:58:34Z"),
                        "configVersion" : 3,
                        "configTerm" : 2,
                        "self" : true,
                        "lastHeartbeatMessage" : ""
                },
                {
                        "_id" : 2,
                        "name" : "node03:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 1914,
                        "optime" : {
                                "ts" : Timestamp(1605013164, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(1605013164, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2020-11-10T12:59:24Z"),
                        "optimeDurableDate" : ISODate("2020-11-10T12:59:24Z"),
                        "lastHeartbeat" : ISODate("2020-11-10T12:59:24.459Z"),
                        "lastHeartbeatRecv" : ISODate("2020-11-10T12:59:25.506Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "node02:27017",
                        "syncSourceId" : 1,
                        "infoMessage" : "",
                        "configVersion" : 3,
                        "configTerm" : 2
                }
        ],
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605013164, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605013164, 1)
}
test_replset:PRIMARY>

　　提示：能够看到当node01上的mongodb服务停掉之后，对应的主节点也就不可以正常的向从节点发送心跳，因此剩下的两个从节点都认为主节点挂了，此时他俩就开始从新选举主节点；咱们再次链接到node02上的mongodb查看副本集状态时，此时node02上的mongodb就成为了主节点；同时咱们也能看到node01的健康状态为0，表示不健康；

　　查看从节点的复制信息

test_replset:PRIMARY> rs.printSecondaryReplicationInfo()
source: node01.test.org:27017
        syncedTo: Thu Jan 01 1970 08:00:00 GMT+0800 (CST)
        1605013534 secs (445837.09 hrs) behind the primary 
source: node03:27017
        syncedTo: Tue Nov 10 2020 21:05:34 GMT+0800 (CST)
        0 secs (0 hrs) behind the primary 
test_replset:PRIMARY>

　　提示：这里能够看到node01落后主节点很长时间，node03不落后主节点；

　　查看同步信息时间窗口，以及oplog大小

test_replset:PRIMARY> rs.printReplicationInfo()
configured oplog size:   2048MB
log length start to end: 2291secs (0.64hrs)
oplog first event time:  Tue Nov 10 2020 20:27:23 GMT+0800 (CST)
oplog last event time:   Tue Nov 10 2020 21:05:34 GMT+0800 (CST)
now:                     Tue Nov 10 2020 21:05:35 GMT+0800 (CST)
test_replset:PRIMARY>

　　提示：能够看到oplog的小为2048MB，日志开始到结束的时间窗口为2291秒，意思是说当前启动副本集到查询复制信息是的时长为2291秒；第一个oplog时间时间和最后oplog事件时间以及如今的时间均可查看获得；

　　移除节点（从副本集中，将node01节点移除）

test_replset:PRIMARY> rs.remove("node01.test.org:27017")
{
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605014063, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605014063, 1)
}
test_replset:PRIMARY> rs.status()
{
        "set" : "test_replset",
        "date" : ISODate("2020-11-10T13:14:35.362Z"),
        "myState" : 1,
        "term" : NumberLong(2),
        "syncSourceHost" : "",
        "syncSourceId" : -1,
        "heartbeatIntervalMillis" : NumberLong(2000),
        "majorityVoteCount" : 2,
        "writeMajorityCount" : 2,
        "votingMembersCount" : 2,
        "writableVotingMembersCount" : 2,
        "optimes" : {
                "lastCommittedOpTime" : {
                        "ts" : Timestamp(1605014074, 1),
                        "t" : NumberLong(2)
                },
                "lastCommittedWallTime" : ISODate("2020-11-10T13:14:34.514Z"),
                "readConcernMajorityOpTime" : {
                        "ts" : Timestamp(1605014074, 1),
                        "t" : NumberLong(2)
                },
                "readConcernMajorityWallTime" : ISODate("2020-11-10T13:14:34.514Z"),
                "appliedOpTime" : {
                        "ts" : Timestamp(1605014074, 1),
                        "t" : NumberLong(2)
                },
                "durableOpTime" : {
                        "ts" : Timestamp(1605014074, 1),
                        "t" : NumberLong(2)
                },
                "lastAppliedWallTime" : ISODate("2020-11-10T13:14:34.514Z"),
                "lastDurableWallTime" : ISODate("2020-11-10T13:14:34.514Z")
        },
        "electionCandidateMetrics" : {
                "lastElectionReason" : "stepUpRequestSkipDryRun",
                "lastElectionDate" : ISODate("2020-11-10T12:58:34.398Z"),
                "electionTerm" : NumberLong(2),
                "lastCommittedOpTimeAtElection" : {
                        "ts" : Timestamp(1605013112, 1),
                        "t" : NumberLong(1)
                },
                "lastSeenOpTimeAtElection" : {
                        "ts" : Timestamp(1605013112, 1),
                        "t" : NumberLong(1)
                },
                "numVotesNeeded" : 2,
                "priorityAtElection" : 1,
                "electionTimeoutMillis" : NumberLong(10000),
                "priorPrimaryMemberId" : 0,
                "numCatchUpOps" : NumberLong(0),
                "newTermStartDate" : ISODate("2020-11-10T12:58:34.410Z"),
                "wMajorityWriteAvailabilityDate" : ISODate("2020-11-10T12:58:34.506Z")
        },
        "members" : [
                {
                        "_id" : 1,
                        "name" : "node02:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 3897,
                        "optime" : {
                                "ts" : Timestamp(1605014074, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2020-11-10T13:14:34Z"),
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "",
                        "electionTime" : Timestamp(1605013114, 1),
                        "electionDate" : ISODate("2020-11-10T12:58:34Z"),
                        "configVersion" : 4,
                        "configTerm" : 2,
                        "self" : true,
                        "lastHeartbeatMessage" : ""
                },
                {
                        "_id" : 2,
                        "name" : "node03:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 2824,
                        "optime" : {
                                "ts" : Timestamp(1605014063, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(1605014063, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2020-11-10T13:14:23Z"),
                        "optimeDurableDate" : ISODate("2020-11-10T13:14:23Z"),
                        "lastHeartbeat" : ISODate("2020-11-10T13:14:33.958Z"),
                        "lastHeartbeatRecv" : ISODate("2020-11-10T13:14:33.970Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "node02:27017",
                        "syncSourceId" : 1,
                        "infoMessage" : "",
                        "configVersion" : 4,
                        "configTerm" : 2
                }
        ],
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605014074, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605014074, 1)
}
test_replset:PRIMARY>

　　提示：移除节点须要写明对应节点的主机名地址和端口，或者是ip地址端口；这个字串必须是同加入到副本集中的名字相同才可移除，不然它会提示咱们给定主机字符串找不到；

　　设置node03的优先级为10

test_replset:PRIMARY> cfg = rs.conf()
{
        "_id" : "test_replset",
        "version" : 4,
        "term" : 2,
        "protocolVersion" : NumberLong(1),
        "writeConcernMajorityJournalDefault" : true,
        "members" : [
                {
                        "_id" : 1,
                        "host" : "node02:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 1,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                },
                {
                        "_id" : 2,
                        "host" : "node03:27017",
                        "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("5faa85853d5a2d8fdf8af85e")
        }
}
test_replset:PRIMARY> cfg.members[1].priority = 10
10
test_replset:PRIMARY> rs.reconfig(cfg)
{
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605015945, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605015945, 1)
}
test_replset:PRIMARY> rs.config()
{
        "_id" : "test_replset",
        "version" : 5,
        "term" : 3,
        "protocolVersion" : NumberLong(1),
        "writeConcernMajorityJournalDefault" : true,
        "members" : [
                {
                        "_id" : 1,
                        "host" : "node02:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 1,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                },
                {
                        "_id" : 2,
                        "host" : "node03:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 10,
                        "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("5faa85853d5a2d8fdf8af85e")
        }
}
test_replset:SECONDARY>

　　提示：设置某个成员的优先级，首先要把当前配置用一个变量保存，而后经过修改保存的配置变量来修改优先级之后，再使用rs.reconfig()来读取修改后的配置便可生效；这里须要注意我在修改配置文件时指定成员，是指定对应成员在members列表的下标，而非id；因此修改前要先肯定对应成员的下标是多少；咱们修改了node03的优先级之后，心细的你必定会发现node02此时就变成了secondary;这意味着，只要在副本集中有更高优先级的成员加入，会触发一次选举，固然选举成为主节点，影响最大的就是各节点的优先级，优先级越高，当选主节点的概率就越大；默认状况每一个成员的优先级都为1，优先级设定的取值范围是0-1000；

　　将node01上的mongodb服务启动起来，而后在主节点上将其添加为仲裁节点

　　启动node01上的mongodb服务

[root@node01 ~]# systemctl start mongod.service 
[root@node01 ~]# ss -tnl
State      Recv-Q Send-Q           Local Address:Port                          Peer Address:Port              
LISTEN     0      128                          *:22                                       *:*                  
LISTEN     0      100                  127.0.0.1:25                                       *:*                  
LISTEN     0      128                          *:27017                                    *:*                  
LISTEN     0      128                         :::22                                      :::*                  
LISTEN     0      100                        ::1:25                                      :::*                  
[root@node01 ~]#

　　在主节点上将node01添加为仲裁节点

test_replset:PRIMARY> rs.addArb("node01")
{
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1605016848, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1605016848, 1)
}
test_replset:PRIMARY>

　　查看配置信息，看看node01上的arbiterOnly是否变成了true?

test_replset:PRIMARY> rs.config()
{
        "_id" : "test_replset",
        "version" : 8,
        "term" : 3,
        "protocolVersion" : NumberLong(1),
        "writeConcernMajorityJournalDefault" : true,
        "members" : [
                {
                        "_id" : 1,
                        "host" : "node02:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 1,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                },
                {
                        "_id" : 2,
                        "host" : "node03:27017",
                        "arbiterOnly" : false,
                        "buildIndexes" : true,
                        "hidden" : false,
                        "priority" : 10,
                        "tags" : {

                        },
                        "slaveDelay" : NumberLong(0),
                        "votes" : 1
                },
                {
                        "_id" : 3,
                        "host" : "node01:27017",
                        "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("5faa85853d5a2d8fdf8af85e")
        }
}
test_replset:PRIMARY>

　　提示：能够看到node01节点上的arbiterOnly属性已经启用，说明这就是一个仲裁节点；咱们说过仲裁节点上没有保存副本，咱们到node01上看看是否保存的有副本集数据呢？

test_replset:ARBITER> show databases
uncaught exception: Error: listDatabases failed:{
        "topologyVersion" : {
                "processId" : ObjectId("5faa9d87e504fa222c4a584d"),
                "counter" : NumberLong(1)
        },
        "ok" : 0,
        "errmsg" : "not master and slaveOk=false",
        "code" : 13435,
        "codeName" : "NotMasterNoSlaveOk"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs/<@src/mongo/shell/mongo.js:147:19
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:99:12
shellHelper.show@src/mongo/shell/utils.js:937:13
shellHelper@src/mongo/shell/utils.js:819:15
@(shellhelp2):1:1
test_replset:ARBITER> rs.secondaryOk()
test_replset:ARBITER> show databases
uncaught exception: Error: listDatabases failed:{
        "topologyVersion" : {
                "processId" : ObjectId("5faa9d87e504fa222c4a584d"),
                "counter" : NumberLong(1)
        },
        "ok" : 0,
        "errmsg" : "node is not in primary or recovering state",
        "code" : 13436,
        "codeName" : "NotMasterOrSecondary"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs/<@src/mongo/shell/mongo.js:147:19
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:99:12
shellHelper.show@src/mongo/shell/utils.js:937:13
shellHelper@src/mongo/shell/utils.js:819:15
@(shellhelp2):1:1
test_replset:ARBITER>

　　提示：咱们在仲裁节点上查看数据库列表，它提示咱们不是主节点和从节点，不容许读；既然都不容许读，写确定是没有办法进行；

　　ok,到此mongodb的副本集的配置、测试就到此为止；