errmsg has data already, cannot initiate set

今天在做mongoDB主从的时候，遇到了"has data already, cannot initiate set"的问题，正好看到之前有人也遇到这个问题，老师回答说是要把从的数据全部清空，结果我在从上清空，也会报错。(:<(, woops)

主上初始化的时候提示信息如下：

> rs.initiate(config)
{
"ok" : 0,
"errmsg" : "'192.168.3.220:27017' has data already, cannot initiate set.",
"code" : 110
}

从上清空数据报错信息如下：

> db.dropDatabase()
{ "note" : "from execCommand", "ok" : 0, "errmsg" : "<span style="color:#CC0000;"><strong>not master</strong></span>" } ## CAUTION: 已经配置主从了，赶紧把主从配置取消掉，怀疑就是主从配置导致数据无法正常清空。
>
> show dbs
2016-04-25T22:18:50.226+0800 E QUERY    Error: listDatabases failed:{ "note" : "from execCommand", "ok" : 0, "errmsg" : "not master" }
at Error (<anonymous>)
at Mongo.getDBs (src/mongo/shell/mongo.js:47:15)
at shellHelper.show (src/mongo/shell/utils.js:630:33)
at shellHelper (src/mongo/shell/utils.js:524:36)
at (shellhelp2):1:1 at src/mongo/shell/mongo.js:47

排错步骤：

1、把从配置文件主从配置去掉

2、重启服务

3、在从上执行db.dropDatabase(),清空所有的数据库，一个也不要留，直到show dbs为空

4、主上初始化，执行rs.initiate(config)，这个时候又开悲摧了，

holy shit!!!!! ^__^

> rs.initiate(config)
{
"ok" : 0,
"errmsg" : "replSetInitiate quorum check failed because not all proposed set members responded affirmatively: 192.168.3.221:27017 failed with Failed attempt to connect to 192.168.3.221:27017; couldn't connect to server 192.168.3.221:27017 (192.168.3.221), connection attempt failed",
"code" : 74
}

"errmsg" : "replSetInitiate quorum check failed because
not all proposed set members responded affirmatively: ##这里说是不是所有的成员都已经果断的响应，我英文不怎么样就直译了，离成功不远了，再去从上找问题。

a、查看selinux是关闭的，这个先排除

b、iptables -nvL， wps， 天呐，这么多防火墙规则，关了它。

[root@A ~]# getenforce
Disabled
[root@A ~]# iptables -nvL
Chain INPUT (policy ACCEPT 3058 packets, 344K bytes)
pkts bytes target     prot opt in     out     source               destination
0     0 ACCEPT     udp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           udp dpt:53
0     0 ACCEPT     tcp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           tcp dpt:53
0     0 ACCEPT     udp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           udp dpt:67
0     0 ACCEPT     tcp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           tcp dpt:67

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source               destination
0     0 ACCEPT     all  --  *      virbr0  0.0.0.0/0            192.168.122.0/24    state RELATED,ESTABLISHED
0     0 ACCEPT     all  --  virbr0 *       192.168.122.0/24     0.0.0.0/0
0     0 ACCEPT     all  --  virbr0 virbr0  0.0.0.0/0            0.0.0.0/0
0     0 REJECT     all  --  *      virbr0  0.0.0.0/0            0.0.0.0/0           reject-with icmp-port-unreachable
0     0 REJECT     all  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-port-unreachable

Chain OUTPUT (policy ACCEPT 3499 packets, 375K bytes)
pkts bytes target     prot opt in     out     source               destination
[root@A ~]# iptables -F
[root@A ~]# service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[  OK  ]
[root@A ~]# service iptables stop
iptables: Setting chains to policy ACCEPT: nat mangle filte[  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]

c、重新启动mongod服务

d、在主上继续执行初始化命令，成功了。

> rs.initiate(config)
{ "ok" : 1 }
changfeng:OTHER> rs.status()
{
"set" : "changfeng",
"date" : ISODate("2016-04-25T15:20:32.062Z"),
"myState" : 1,
"members" : [
{
"_id" : 0,
"name" : "192.168.3.219:27017",
"health" : 1,
"state" : 1,
"stateStr" : "<span style="color:#FF0000;">PRIMARY</span>",
"uptime" : 3263,
"optime" : Timestamp(1461596226, 1),
"optimeDate" : ISODate("2016-04-25T14:57:06Z"),
"electionTime" : Timestamp(1461596228, 1),
"electionDate" : ISODate("2016-04-25T14:57:08Z"),
"configVersion" : 1,
"self" : true
},
{
"_id" : 1,
"name" : "192.168.3.220:27017",
"health" : 1,
"state" : 2,
"stateStr" : "<span style="color:#FF0000;">SECONDARY</span>",
"uptime" : 1405,
"optime" : Timestamp(1461596226, 1),
"optimeDate" : ISODate("2016-04-25T14:57:06Z"),
"lastHeartbeat" : ISODate("2016-04-25T15:20:30.162Z"),
"lastHeartbeatRecv" : ISODate("2016-04-25T15:20:30.168Z"),
"pingMs" : 0,
"configVersion" : 1
},
{
"_id" : 2,
"name" : "192.168.3.221:27017",
"health" : 1,
"state" : 2,
"stateStr" : "<span style="color:#FF0000;">SECONDARY</span>",
"uptime" : 1405,
"optime" : Timestamp(1461596226, 1),
"optimeDate" : ISODate("2016-04-25T14:57:06Z"),
"lastHeartbeat" : ISODate("2016-04-25T15:20:31.037Z"),
"lastHeartbeatRecv" : ISODate("2016-04-25T15:20:31.044Z"),
"pingMs" : 0,
"configVersion" : 1
}
],
"ok" : 1
}

好了，遇到问题不要着急，先静下心来，保持平静，一步一步的查。肯定有解决的时候。加油。