之前写过一篇，ambari2.1升级到2.4的步骤，下面将ambari1.7升级到2.1的步骤汇总下，这里不建议从ambari1.7升级到2.1后再次继续升级到2.4版本，目前已知hive服务出现问题，服务无法运行。
为什么要升级版本，因为新版本会有更多的功能，ambari1.7没有服务删除的功能，部分服务没有Move的功能，没有机架感知，新的ambari版本增加了更多功能。
官方升级版本说明
http://docs.hortonworks.com/HDPDocuments/Ambari-2.4.0.1/bk_ambari-installation/content/determine_stack_compatibility.html
官方升级步骤
http://docs.hortonworks.com/HDPDocuments/Ambari-2.4.0.1/bk_ambari-upgrade/content/preparing_to_upgrade_ambari.html
官方HDP问题搜索
https://community.hortonworks.com/answers/index.html
（这里我没有找到1.7升级到2.1版本的官方步骤，上面是ambari2.1升级到2.4的步骤，操作是一样的）
一、升级前准备
Preparing to Upgrade
确认版本
Be sure to review the Release Notes for this Ambari release for Known Issues and Behavioral Changes.
拥有root权限
You must have root, administrative, or root-equivalent authorization on the Ambari server host and all servers in the cluster.
备份ambari数据库
You must backup the Ambari Server database.
备份好ambari.properties配置文件
You must make a safe copy of the Ambari Server configuration file found at /etc/ambari-server/conf/ambari.properties.
二、停止服务、下载新的ambari.repo
ambari-server stop
ambari-agent stop
wget -nv http://public-repo-1.hortonworks.com/ambari/centos6/2.x/updates/2.1.2.1/ambari.repo -O /etc/yum.repos.d/ambari.repo
三、升级操作
Upgrade Ambari Server. On the host running Ambari Server:
yum clean all
yum info ambari-server
在ambari节点更新ambari-server
In the info output, visually validate that there is an available version containing "2.1"
yum upgrade ambari-server
显示如下成功：
Updated:
ambari-server.x86_64 0:2.1.2.1-1
Complete!
在所有节点更新ambari-agent
Upgrade all Ambari Agents. On each host in your cluster running an Ambari Agent:
yum upgrade ambari-agent
显示如下成功：
Updated:
ambari-agent.x86_64 0:2.1.2.1-1
Complete!
查看ambari-agent
After the upgrade process completes, check each host to make sure the new files have been installed:
rpm -qa | grep ambari-agent
升级ambari-server
Upgrade Ambari Server database schema. On the host running Ambari Server:
ambari-server upgrade
[root@hadooptest50 ~]# ambari-server upgrade
Using python /usr/bin/python2.6
Upgrading ambari-server
Updating properties in ambari.properties ...
WARNING: Can not find ambari-env.sh.rpmsave file from previous version, skipping restore of environment settings
Fixing database objects owner
Ambari Server configured for MySQL. Confirm you have made a backup of the Ambari Server database [y/n] (y)? y
Upgrading database schema
Adjusting ambari-server permissions and ownership...
Ambari Server 'upgrade' completed successfully.
启动ambari-server
Start the Ambari Server. On the host running Ambari Server:
ambari-server start
[root@testserver2 yum.repos.d]# ambari-server start
Using python /usr/bin/python
Starting ambari-server
Ambari Server running with administrator privileges.
Organizing resource files at /var/lib/ambari-server/resources...
Ambari database consistency check started...
No errors were found.
Ambari database consistency check finished
Server PID at: /var/run/ambari-server/ambari-server.pid
Server out at: /var/log/ambari-server/ambari-server.out
Server log at: /var/log/ambari-server/ambari-server.log
Waiting for server start....................
Ambari Server 'start' completed successfully.
所有节点启动ambari-agent
Start all Ambari Agents. On each host in your cluster running an Ambari Agent:
ambari-agent start
登录ambari管理界面，查看版本，升级成功。
登录后有个告警，关于HBase Master，但我并没有安装hbase，莫名其妙的告警，这个点进去可以关闭，就不会提示了。
因为ambari2.1版本，服务中不在有ganglia、nagios，增加组件Metrics代替性能监控，所以界面中CPU、Memory信息图表没有了，但通过原来的ganglia、nagios链接还可以访问，ambari界面上只有gnaglia服务可以控制，nagios消失了。
安装下ambari-metrics后，就会出现性能图
ambari升级后，界面中增加服务的组件也会变了，之前1.7有ganglia、nagios，升级后就不见了，增加组件中有Metrics代替性能监控。