IT博客汇 | [原]mongodb 最新版本高可用解决方案-replica sets副本集部署详细过程

[原]mongodb 最新版本高可用解决方案-replica sets副本集部署详细过程

mchdba发表于 2016-06-11 21:17:36

Mongodb副本集：

NoSQL的产生就是为了解决大数据量、高扩展性、高性能、灵活数据模型、高可用性。但是光通过主从模式的架构远远达不到上面几点，由此MongoDB设计了副本集和分片的功能，先来用用副本集。

Mongodb副本集的同步机制：

数据复制的目的是使数据得到最大的可用性，避免单点故障引起的整站不能访问的情况的发生，Mongodb的副本集在同一时刻只有一台服务器是可以写的，副本集的主从复制也是一个异步同步的过程，是slave端从primary端获取日志，然后在自己身上完全顺序的执行日志所记录的各种操作（该日志是不记录查询操作的），这个日志就是local数据库中的oplog.rs表，默认在64位机器上这个表是比较大的，占磁盘大小的5%，oplog.rs的大小可以在启动参数中设定：--oplogSize 1000,单位是M。

1，设置yum源安装

创建/etc/yum.repos.d/mongodb-enterprise.repo文件，这样就可以使用yum来安装mongodb了。

[mongodb-org-3.0]

name=MongoDB Repository

baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/3.0/x86_64/

gpgcheck=1

enabled=1

gpgkey=https://www.mongodb.org/static/pgp/server-3.0.asc

每一个release版本的.repo文件可以在repository找到，记住奇数镜像版本（比如e.g.2.5）是开发版本，放在生成环境是不太合适的。

2，源码安装

2.1 下载安装包

在官方网站可以下载到比较新的版本，下载地址：

https://www.mongodb.org/dr/fastdl.mongodb.org/linux/mongodb-linux-x86_64-3.2.3.tgz/download；

我这里下载的是稳定版本：mongodb-linux-x86_64-3.0.3.tgz，安装也是用的3.0.3； 3.0.3的下载地址为：http://download.csdn.net/detail/mchdba/9546256

2.2 解压安装

tar -xvf mongodb-linux-x86_64-3.0.3.tgz -C /usr/local/

3 启动3个mongodb服务

安装mongodbreplica sets，至少需要3台linux服务器，而初始化副本集合，本来应该是3台服务器，但是这里只是测试环境，启用了3个mongodb端口进程来来模拟3个mongodb的服务器达到一样的效果，在实际中，可以部署在多台mongodb服务器上，如下表所示：

Mongodb 主机	服务器端口地址	默认角色
mongodb主机 1	localhost:27017	primary
mongodb主机 2	localhost:27018	secondary
mongodb主机 3	localhost:27019	secondary

开始启动3个mongodb服务：

# 启动第一个mongodb 27017，默认为primary服务器

mkdir -p /data/mongodb/log27017

mkdir -p /data/mongodb/data27017

/usr/local/mongodb-linux-x86_64-3.0.3/bin/mongod --replSet repset --port 27017 --dbpath /data/mongodb/data27017 --oplogSize 2048 --logpath /data/mongodb/log27017/mongod.log &

# 启动第二个mongodb 27018

mkdir -p /data/mongodb/log27018

mkdir -p /data/mongodb/data27018

/usr/local/mongodb-linux-x86_64-3.0.3/bin/mongod --replSet repset --port 27018 --dbpath /data/mongodb/data27018 --oplogSize 2048 --logpath /data/mongodb/log27018/mongod.log &

# 启动第三个 mongodb 27019

mkdir -p /data/mongodb/log27019

mkdir -p /data/mongodb/data27019

/usr/local/mongodb-linux-x86_64-3.0.3/bin/mongod --replSet repset --port 27019 --dbpath /data/mongodb/data27019 --oplogSize 2048 --logpath /data/mongodb/log27019/mongod.log &

4 添加replica sets配置

在任何一台mongodb实例上登录，进入admin库，执行config命令：

> use admin

switched to db admin

config = { _id:"repset", members:[

... {_id:0,host:"mongodb_server:27017"},

... {_id:1,host:"mongodb_server:27018"},

... {_id:2,host:"mongodb_server:27019"}]

... };

> config = { _id:"repset", members:[

... ... {_id:0,host:"mongodb_server:27017"},

... ... {_id:1,host:"mongodb_server:27018"},

... ... {_id:2,host:"mongodb_server:27019"}]

... ... };

{

"_id" : "repset",

"members" : [

{

"_id" : 0,

"host" : "mongodb_server:27017"

{

"_id" : 1,

"host" : "mongodb_server:27018"

{

"_id" : 2,

"host" : "mongodb_server:27019"

}

]

}

5 初始化副本集

# 初始化副本集配置，使用rs.initiate(config);命令

rs.initiate(config);

> rs.initiate(config);

{ "ok" : 1 }

repset:SECONDARY>

6 查看replica sets状态

看到config配置里面的第一个默认为primary，后面的都为secondary，然后查看"optime": Timestamp(1465641737, 1)，如果集合中的mongodb的optime一致，表是集群中各个mongodb数据是保持一致性的：

# 随意登录一个mongodb服务

[root@oracle_master ~]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27017

MongoDB shell version: 3.0.3

connecting to: localhost:27017/test

Server has startup warnings:

2016-06-10T07:56:33.333-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-10T07:56:33.333-0700 I CONTROL [initandlisten]

repset:PRIMARY> use admin

switched to db admin

repset:PRIMARY>

# 查看状态如下：

repset:PRIMARY> rs.status();

{

"set" : "repset",

"date" : ISODate("2016-06-10T15:04:54.045Z"),

"myState" : 1,

"members" : [

{

"_id" : 0,

"name" : "mongodb_server:27017",

"health" : 1,

"state" : 1,

"stateStr" : "PRIMARY",

"uptime" : 501,

"optime" : Timestamp(1465571046, 1),

"optimeDate" : ISODate("2016-06-10T15:04:06Z"),

"electionTime" : Timestamp(1465571050, 1),

"electionDate" : ISODate("2016-06-10T15:04:10Z"),

"configVersion" : 1,

"self" : true

{

"_id" : 1,

"name" : "mongodb_server:27018",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 47,

"optime" : Timestamp(1465571046, 1),

"optimeDate" : ISODate("2016-06-10T15:04:06Z"),

"lastHeartbeat" : ISODate("2016-06-10T15:04:52.493Z"),

"lastHeartbeatRecv" : ISODate("2016-06-10T15:04:52.612Z"),

"pingMs" : 1,

"configVersion" : 1

{

"_id" : 2,

"name" : "mongodb_server:27019",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 47,

"optime" : Timestamp(1465571046, 1),

"optimeDate" : ISODate("2016-06-10T15:04:06Z"),

"lastHeartbeat" : ISODate("2016-06-10T15:04:52.642Z"),

"lastHeartbeatRecv" : ISODate("2016-06-10T15:04:52.642Z"),

"pingMs" : 0,

"lastHeartbeatMessage" : "could not find member to sync from",

"configVersion" : 1

}

"ok" : 1

}

repset:PRIMARY>

7，查看后台日志

可以看到27107的mongodb默认成为了primary，而27018和27019的成为了secondary了：

[root@oracle_master ~]# tail -f /data/mongodb/log27017/mongod.log

2016-06-11T03:42:19.664-0700 I REPL [ReplicationExecutor] replSet election succeeded, assuming primary role

2016-06-11T03:42:19.664-0700 I REPL [ReplicationExecutor] transition to PRIMARY

2016-06-11T03:42:19.686-0700 I REPL [ReplicationExecutor] Member mongodb_server:27019 is now in state STARTUP2

2016-06-11T03:42:19.738-0700 I REPL [rsSync] transition to primary complete; database writes are now permitted

2016-06-11T03:42:22.798-0700 I NETWORK [initandlisten] connection accepted from 192.168.136.128:18197 #6 (4 connections now open)

2016-06-11T03:42:22.812-0700 I NETWORK [initandlisten] connection accepted from 192.168.136.128:18198 #7 (5 connections now open)

2016-06-11T03:42:22.849-0700 I NETWORK [conn6] end connection 192.168.136.128:18197 (4 connections now open)

2016-06-11T03:42:22.906-0700 I NETWORK [conn7] end connection 192.168.136.128:18198 (3 connections now open)

2016-06-11T03:42:23.668-0700 I REPL [ReplicationExecutor] Member mongodb_server:27018 is now in state SECONDARY

2016-06-11T03:42:23.689-0700 I REPL [ReplicationExecutor] Member mongodb_server:27019 is now in state SECONDARY

8，验证replica sets 数据一致性

（1）先进去主库primary的mongodb上，录入数据：

# 登录primary主库

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27017

MongoDB shell version: 3.0.3

connecting to: localhost:27017/test

Server has startup warnings:

2016-06-11T03:41:07.938-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-11T03:41:07.938-0700 I CONTROL [initandlisten]

repset:PRIMARY>

# 录入数据

repset:PRIMARY> use yes_db;

switched to db yes_db

repset:PRIMARY> db.yes_users.insert({"uid":"20160611_0001"},{"uname":"tim.man"});

WriteResult({ "nInserted" : 1 })

repset:PRIMARY>

（2）去第一个备库27018上，验证数据，有了yes_users表的数据，如下：

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27018

MongoDB shell version: 3.0.3

connecting to: localhost:27018/test

Server has startup warnings:

2016-06-11T03:41:14.305-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-11T03:41:14.305-0700 I CONTROL [initandlisten]

repset:SECONDARY> use yes_db;

switched to db yes_db

repset:SECONDARY> show tables;

2016-06-11T04:03:02.088-0700 E QUERY Error: listCollections failed: { "note" : "from execCommand", "ok" : 0, "errmsg" : "not master" }

at Error (<anonymous>)

at DB._getCollectionInfosCommand (src/mongo/shell/db.js:646:15)

at DB.getCollectionInfos (src/mongo/shell/db.js:658:20)

at DB.getCollectionNames (src/mongo/shell/db.js:669:17)

at shellHelper.show (src/mongo/shell/utils.js:625:12)

at shellHelper (src/mongo/shell/utils.js:524:36)

at (shellhelp2):1:1 at src/mongo/shell/db.js:646

# mongodb默认是从主节点读写数据的，副本节点上不允许读，需要设置副本节点可以读。

repset:SECONDARY> db.getMongo().setSlaveOk();

repset:SECONDARY> show tables;

system.indexes

yes_users

repset:SECONDARY> db.yes_users.find(); # 看到有数据了

{ "_id" : ObjectId("575bef8126150b8de92029eb"), "uid" : "20160611_0001" }

repset:SECONDARY>

（3）去第二个secondary备库27019上，检查数据是否已经复制过来：

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27019

MongoDB shell version: 3.0.3

connecting to: localhost:27019/test

Server has startup warnings:

2016-06-11T03:41:20.363-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-11T03:41:20.363-0700 I CONTROL [initandlisten]

repset:SECONDARY> use yes_db

switched to db yes_db

repset:SECONDARY> db.getMongo().setSlaveOk();# mongodb默认是从主节点读写数据的，副本节点上不允许读，需要设置副本节点可以读。

repset:SECONDARY> db.yes_users.find();# 看到有数据了，数据已经复制过来。

{ "_id" : ObjectId("575bef8126150b8de92029eb"), "uid" : "20160611_0001" }

repset:SECONDARY>

9，验证primary、secondary自动切换

9.1 自动切换示意图

官方介绍：https://docs.mongodb.com/master/core/replica-set-high-availability/

Replica Set High Availability

Replica sets provide high availability using automatic failover. Failover allows a secondary member to become primary if the current primary becomes unavailable.

9.2 验证自动切换操作

当primary不可用，则自动将合适的secondary成员切换成新的primary，接下来的(1)-> (5)就来验证这个：

（1）关闭27017的mongod服务，即停止primary主库：

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27017

MongoDB shell version: 3.0.3

connecting to: localhost:27017/test

Server has startup warnings:

2016-06-11T03:41:07.938-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-11T03:41:07.938-0700 I CONTROL [initandlisten]

repset:PRIMARY> use admin

switched to db admin

repset:PRIMARY> db.shutdownServer();

2016-06-11T04:18:24.148-0700 I NETWORK DBClientCursor::init call() failed

server should be down...

2016-06-11T04:18:24.151-0700 I NETWORK trying reconnect to localhost:27017 (127.0.0.1) failed

2016-06-11T04:18:24.152-0700 I NETWORK reconnect localhost:27017 (127.0.0.1) ok

2016-06-11T04:18:24.437-0700 I NETWORK Socket recv() errno:104 Connection reset by peer 127.0.0.1:27017

2016-06-11T04:18:24.437-0700 I NETWORK SocketException: remote: 127.0.0.1:27017 error: 9001 socket exception [RECV_ERROR] server [127.0.0.1:27017]

2016-06-11T04:18:24.437-0700 I NETWORK DBClientCursor::init call() failed

2016-06-11T04:18:24.440-0700 I NETWORK trying reconnect to localhost:27017 (127.0.0.1) failed

2016-06-11T04:18:24.441-0700 W NETWORK Failed to connect to 127.0.0.1:27017, reason: errno:111 Connection refused

2016-06-11T04:18:24.441-0700 I NETWORK reconnect localhost:27017 (127.0.0.1) failed failed couldn't connect to server localhost:27017 (127.0.0.1), connection attempt failed

（2）登录原来的主库primary库的mongodb，就会报错：

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27017

MongoDB shell version: 3.0.3

connecting to: localhost:27017/test

2016-06-11T04:20:40.597-0700 W NETWORK Failed to connect to 127.0.0.1:27017, reason: errno:111 Connection refused

2016-06-11T04:20:40.614-0700 E QUERY Error: couldn't connect to server localhost:27017 (127.0.0.1), connection attempt failed

at connect (src/mongo/shell/mongo.js:181:14)

at (connect):1:6 at src/mongo/shell/mongo.js:181

exception: connect failed

[root@oracle_master mongodb]#

（3） primary自动切换到下一个mongodb服务，即27018端口的mongodb为primary服务：

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27018

MongoDB shell version: 3.0.3

connecting to: localhost:27018/test

Server has startup warnings:

2016-06-11T03:41:14.305-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-11T03:41:14.305-0700 I CONTROL [initandlisten]

repset:PRIMARY> rs.status();

{

"set" : "repset",

"date" : ISODate("2016-06-11T11:20:50.730Z"),

"myState" : 1,

"members" : [

{

"_id" : 0,

"name" : "mongodb_server:27017",

"health" : 0,

"state" : 8,

"stateStr" : "(not reachable/healthy)",

"uptime" : 0,

"optime" : Timestamp(0, 0),

"optimeDate" : ISODate("1970-01-01T00:00:00Z"),

"lastHeartbeat" : ISODate("2016-06-11T11:20:50.467Z"),

"lastHeartbeatRecv" : ISODate("2016-06-11T11:18:22.616Z"),

"pingMs" : 6,

"lastHeartbeatMessage" : "Failed attempt to connect to mongodb_server:27017; couldn't connect to server mongodb_server:27017 (192.168.136.128), connection attempt failed",

"configVersion" : -1

{

"_id" : 1,

"name" : "mongodb_server:27018",

"health" : 1,

"state" : 1,

"stateStr" : "PRIMARY",

"uptime" : 2377,

"optime" : Timestamp(1465642881, 2),

"optimeDate" : ISODate("2016-06-11T11:01:21Z"),

"electionTime" : Timestamp(1465643906, 1),

"electionDate" : ISODate("2016-06-11T11:18:26Z"),

"configVersion" : 1,

"self" : true

{

"_id" : 2,

"name" : "mongodb_server:27019",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 2312,

"optime" : Timestamp(1465642881, 2),

"optimeDate" : ISODate("2016-06-11T11:01:21Z"),

"lastHeartbeat" : ISODate("2016-06-11T11:20:50.177Z"),

"lastHeartbeatRecv" : ISODate("2016-06-11T11:20:50.718Z"),

"pingMs" : 0,

"configVersion" : 1

}

"ok" : 1

}

repset:PRIMARY>

（4）在27018的后台log里面，也可以看到这一切换记录：

2016-06-11T04:18:25.647-0700 I REPL [ReplicationExecutor] Standing for election

2016-06-11T04:18:25.649-0700 W NETWORK [ReplExecNetThread-6] Failed to connect to 192.168.136.128:27017, reason: errno:111 Connection refused

2016-06-11T04:18:25.649-0700 I REPL [ReplicationExecutor] replSet possible election tie; sleeping 848ms until 2016-06-11T04:18:26.497-0700

2016-06-11T04:18:25.650-0700 I REPL [ReplicationExecutor] Error in heartbeat request to mongodb_server:27017; Location18915 Failed attempt to connect to mongodb_server:27017; couldn't connect to server mongodb_server:27017 (192.168.136.128), connection attempt faile

2016-06-11T04:18:25.650-0700 W NETWORK [ReplExecNetThread-6] Failed to connect to 192.168.136.128:27017, reason: errno:111 Connection refused

2016-06-11T04:18:26.497-0700 I REPL [ReplicationExecutor] Standing for election

2016-06-11T04:18:26.500-0700 I REPL [ReplicationExecutor] replSet info electSelf

2016-06-11T04:18:26.502-0700 I REPL [ReplicationExecutor] replSet election succeeded, assuming primary role

2016-06-11T04:18:26.502-0700 I REPL [ReplicationExecutor] transition to PRIMARY

2016-06-11T04:18:27.333-0700 I REPL [rsSync] transition to primary complete; database writes are now permitted

（5）再启动原来旧的primary库27017端口的mongodb（如果是实际上的坏了就是修复后启动），27017就会自动变成secondary状态。

看到后台mongodb日志：

2016-06-11T04:28:33.979-0700 I NETWORK [initandlisten] connection accepted from 192.168.136.128:11453 #170 (2 connections now open)

2016-06-11T04:28:33.979-0700 I NETWORK [conn170] end connection 192.168.136.128:11453 (1 connection now open)

2016-06-11T04:28:33.992-0700 I NETWORK [initandlisten] connection accepted from 192.168.136.128:11454 #171 (2 connections now open)

2016-06-11T04:28:35.422-0700 I REPL [ReplicationExecutor] Member mongodb_server:27017 is now in state SECONDARY

2016-06-11T04:28:55.672-0700 I NETWORK [conn169] end connection 192.168.136.128:11424 (1 connection now open)

2016-06-11T04:28:55.673-0700 I NETWORK [initandlisten] connection accepted from 192.168.136.128:11459 #172 (2 connections now open)

再查看replica sets状态：

[root@oracle_master mongodb]# /usr/local/mongodb-linux-x86_64-3.0.3/bin/mongo localhost:27018

MongoDB shell version: 3.0.3

connecting to: localhost:27018/test

Server has startup warnings:

2016-06-11T03:41:14.305-0700 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

2016-06-11T03:41:14.305-0700 I CONTROL [initandlisten]

repset:PRIMARY> rs.status();

{

"set" : "repset",

"date" : ISODate("2016-06-11T11:30:00.192Z"),

"myState" : 1,

"members" : [

{

"_id" : 0,

"name" : "mongodb_server:27017",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 85,

"optime" : Timestamp(1465642881, 2),

"optimeDate" : ISODate("2016-06-11T11:01:21Z"),

"lastHeartbeat" : ISODate("2016-06-11T11:29:58.752Z"),

"lastHeartbeatRecv" : ISODate("2016-06-11T11:29:58.263Z"),

"pingMs" : 0,

"configVersion" : 1

{

"_id" : 1,

"name" : "mongodb_server:27018",

"health" : 1,

"state" : 1,

"stateStr" : "PRIMARY",

"uptime" : 2927,

"optime" : Timestamp(1465642881, 2),

"optimeDate" : ISODate("2016-06-11T11:01:21Z"),

"electionTime" : Timestamp(1465643906, 1),

"electionDate" : ISODate("2016-06-11T11:18:26Z"),

"configVersion" : 1,

"self" : true

{

"_id" : 2,

"name" : "mongodb_server:27019",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 2862,

"optime" : Timestamp(1465642881, 2),

"optimeDate" : ISODate("2016-06-11T11:01:21Z"),

"lastHeartbeat" : ISODate("2016-06-11T11:29:59.858Z"),

"lastHeartbeatRecv" : ISODate("2016-06-11T11:29:59.804Z"),

"pingMs" : 0,

"configVersion" : 1

}

"ok" : 1

}

repset:PRIMARY>

至此，验证完成，和理论上示意图上面说的效果是一致的，mongodb的replica sets可以实现高可用解决方案。

10，启动报错

Secondary库启动报错，如下所示：

[root@oracle_master log27018]# more /data/mongodb/log27018/mongod.log

2016-06-11T02:44:32.326-0700 I JOURNAL [initandlisten] journal dir=/data/mongodb/data27018/journal

2016-06-11T02:44:32.326-0700 I JOURNAL [initandlisten] recover : no journal files present, no recovery needed

2016-06-11T02:44:32.326-0700 I JOURNAL [initandlisten]

2016-06-11T02:44:32.326-0700 E JOURNAL [initandlisten] Insufficient free space for journal files

2016-06-11T02:44:32.326-0700 I JOURNAL [initandlisten] Please make at least 3379MB available in /data/mongodb/data27018/journal or use --smallfiles

2016-06-11T02:44:32.326-0700 I JOURNAL [initandlisten]

2016-06-11T02:44:32.327-0700 I STORAGE [initandlisten] exception in initAndListen: 15926 Insufficient free space for journals, terminating

2016-06-11T02:44:32.327-0700 W REPL [initandlisten] ReplicationCoordinatorImpl::shutdown() called before startReplication() finished. Shutting down without cleaning up the replication system

2016-06-11T02:44:32.327-0700 I CONTROL [initandlisten] now exiting

2016-06-11T02:44:32.327-0700 I NETWORK [initandlisten] shutdown: going to close listening sockets...

2016-06-11T02:44:32.327-0700 I NETWORK [initandlisten] removing socket file: /tmp/mongodb-27018.sock

2016-06-11T02:44:32.327-0700 I NETWORK [initandlisten] shutdown: going to flush diaglog...

2016-06-11T02:44:32.327-0700 I NETWORK [initandlisten] shutdown: going to close sockets...

2016-06-11T02:44:32.327-0700 I STORAGE [initandlisten] shutdown: waiting for fs preallocator...

2016-06-11T02:44:32.327-0700 I STORAGE [initandlisten] shutdown: final commit...

2016-06-11T02:44:32.327-0700 I STORAGE [initandlisten] shutdown: closing all files...

2016-06-11T02:44:32.327-0700 I STORAGE [initandlisten] closeAllFiles() finished

2016-06-11T02:44:32.327-0700 I CONTROL [initandlisten] dbexit: rc: 100

[root@oracle_master log27018]#

解决：

看到Please make at least3379MB available in /data/mongodb/data27018/journal or use –smallfiles，所以清理下磁盘空间，磁盘至少要保证有30G以上的空间才行。

网友段书峰blog地址：blog.itpub.net/15498