（2）. Module2 伪分布式模式
上面演示了如何启动单机模式，现在我们来演示设置伪分布式模式。
我们可以在一台机器上创建模拟的ZooKeeper集群服务，假如我们需要3个节点，需要创建3个cfg文件，分别命名为zoo1.cfg，zoo2.cfg，zoo3.cfg，此外我们还需要创建3个不同的数据文件夹，分别是zoo1，zoo2和zoo3，目录位于/var/lib/zookeeper，如1-16、1-17和1-18三个配置清单所示。
清单1-16 配置文件zoo1内容
[root@localhost conf]# cat zoo1.cfg
# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=/var/lib/zookeeper/zoo1
# the port at which the clients will connect
clientPort=2181
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
#http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir
#autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature
#autopurge.purgeInterval=1
server.1=localhost:2666:3666
server.2=localhost:2667:3667
server.3=localhost:2668:3668
清单1-17 配置文件zoo2内容
[root@localhost conf]# cat zoo2.cfg
# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=dataDir=/var/lib/zookeeper/zoo2
# the port at which the clients will connect
clientPort=2182
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
#http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir
#autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature
#autopurge.purgeInterval=1
server.1=localhost:2666:3666
server.2=localhost:2667:3667
server.3=localhost:2668:3668
清单1-18 配置文件zoo3内容
[root@localhost conf]# cat zoo3.cfg
# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=/var/lib/zookeeper/zoo3
# the port at which the clients will connect
clientPort=2183
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
#http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir
#autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature
#autopurge.purgeInterval=1
server.1=localhost:2666:3666
server.2=localhost:2667:3667
server.3=localhost:2668:3668
注意，每一个虚拟机器都对应一个自己的zoo{$}.cfg，其中的{$}需要通过清单1-19所示命令来进行设置。
Tips 由于采用的是“>”，所以命令会创建文件，如果采用“>>”，则Linux会在原有文件基础上新增内容。 |
清单1-19 设置myid
[root@localhost conf]# echo 1 > /var/lib/zookeeper/zoo1/myid
[root@localhost conf]# echo 2 > /var/lib/zookeeper/zoo2/myid
[root@localhost conf]# echo 3 > /var/lib/zookeeper/zoo3/myid
接下来我们开始启动ZooKeeper的3个实例（虚拟的3台机器），需要调用三次zkServer.sh的Start命令，采用不同的配置文件，如清单1-20所示命令及输出。
清单1-20 启动伪分布式集群服务
[root@localhost bin]# ./zkServer.sh start/home/zhoumingyao/zookeeper/zookeeper-3.4.7/conf/zoo1.cfg
ZooKeeper JMX enabled by default
Using config: /home/zhoumingyao/zookeeper/zookeeper-3.4.7/conf/zoo1.cfg
Starting zookeeper ... STARTED
[root@localhost bin]# ./zkServer.sh start/home/zhoumingyao/zookeeper/zookeeper-3.4.7/conf/zoo2.cfg
ZooKeeper JMX enabled by default
Using config: /home/zhoumingyao/zookeeper/zookeeper-3.4.7/conf/zoo2.cfg
Starting zookeeper ... STARTED
[root@localhost bin]# ./zkServer.sh start/home/zhoumingyao/zookeeper/zookeeper-3.4.7/conf/zoo3.cfg
ZooKeeper JMX enabled by default
Using config: /home/zhoumingyao/zookeeper/zookeeper-3.4.7/conf/zoo3.cfg
Starting zookeeper ... STARTED
清单1-21 查看服务
[root@localhost bin]# jps
5537 QuorumPeerMain
5617 Jps
5585 QuorumPeerMain
确认服务都正常启动，我们就可以通过zkCli.sh脚本方式连接到ZooKeeper集群，命令为./zkCli.sh -server localhost:2181,localhost:2182,localhost:2183，效果和单机模式一样。
