前提条件

• 分布式部署模式下替换主机的前提条件：
  • 故障节点不能存在CN实例。
  • 集群中不能存在GTS实例。
  • 集群状态可查，主CM Server状态正常，集群状态不能为Unavailable。
  • 替换前不能锁定集群。
  • 节点替换必须在一个正常主机上执行。
  • 在节点替换前，基于当前集群配置文件执行前置成功。
  • 新物理节点的IP、主机名等信息要和损坏的物理节点一致。
  • 需保证新物理节点和集群其他节点时间一致。
  • 替换实例期间集群不能执行DDL和DML操作。
  • 各节点的系统时间必须同步。
• 主备部署模式下替换主机的前提条件：
  • 集群状态可查，且主CM Server状态正常。
  • 替换前，故障节点上的DN所在的group不能被锁定。
  • 实例替换必须在一个正常主机上执行。
  • 新物理节点的IP、主机名等信息要和损坏的物理节点一致。
  • 需保证新物理节点和集群其他节点时间一致。
  • 在节点替换前，基于当前集群配置文件执行前置成功。
  • 替换节点期间故障节点上的DN所在的group不能执行DDL和DML操作。
  • 各节点的系统时间必须同步。

注意事项

• 替换过程中，请勿执行数据的增删改等DML操作以及DDL操作，否则有可能数据丢失导致数据不一致。
• 在前一次替换结束后才能再次执行替换。因此请不要同时在多个主机上同时执行替换操作。
• 新主机的IP、主机名等信息要和损坏的主机一致。
• 替换前需要先执行前置脚本以完成环境准备。建议在使用gs_preinstall之前，先清理新主机上/tmp/username、二进制程序安装目录、实例数据目录、/var/log/gaussdb/username目录下的内容。

操作步骤

以需要替换新主机名称为plat3为例。

1. 以omm用户身份登录故障节点。
   • 登录成功，则执行步骤2。
   • 登录失败，则执行步骤3。

2. 卸载故障节点上的集群。

   gs_uninstall --delete-data -L

   以omm用户身份登录要使用的新主机。
   

4. 检查字符集。

   echo $LANG
   en_US.UTF-8

   新主机上的字符集、编码方式等信息，使与其它主机保持一致。

   如果不一致请使用如下方式设置字符集。

   export LANG="en_US.UTF-8"

   以root用户登录集群的任意一台正常主机。
   

5. 准备集群环境。

   palt1:/opt/software/gaussdb/script # ./gs_preinstall -U omm -G dbgrp  -X /opt/software/gaussdb/clusterconfig.xml

   其中omm为数据库管理员（也是运行集群的操作系统用户），dbgrp为运行集群的操作系统用户的群组名称，/opt/software/gaussdb/clusterconfig.xml为集群配置文件路径。
   

6. 切换为运行GaussDB 100的操作系统用户。

   palt1:~ # su - omm

   执行如下命令完成新增主机的安装操作。

7. gs_replace -t install -h plat3

   执行如下命令完成新增主机的配置操作。

8. gs_replace -t config -h plat3

   执行如下命令完成新增主机的启动操作。

9. gs_replace -t start -h plat3

   示例（替换主机-不换IP）
   

1. 准备集群环境。

   plat1:/opt/software/gaussdb/script # ./gs_preinstall -U omm -G dbgrp -X /opt/software/gaussdb/clusterconfig.xml
   Parsing the configuration file.
   Successfully parsed the configuration file.
   Installing the tools on the local node.
   Successfully installed the tools on the local node.
   Are you sure you want to create trust for root (yes/no)? yes
   Please enter password for root.
   Password: 
   Creating SSH trust for the root permission user.
   Successfully created SSH trust for the root permission user.
   Pass over configuring LVM
   Distributing package.
   Successfully distributed package.
   Are you sure you want to create the user[omm] and create trust for it (yes/no)? yes
   Please enter password for cluster user.
   Password: 
   Please enter password for cluster user again.
   Password: 
   Creating [omm] user on all nodes.
   Successfully created [omm] user on all nodes.
   Installing the tools in the cluster.
   Successfully installed the tools in the cluster.
   Checking hostname mapping.
   Successfully checked hostname mapping.
   Creating SSH trust for [omm] user.
   Start creating SSH trust for [omm] user.
   Successfully created SSH trust for [omm] user.
   Checking OS version.
   Successfully checked OS version.
   Creating cluster's path.
   Successfully created cluster's path.
   Setting SCTP service.
   Successfully set SCTP service.
   Set and check OS parameter.
   Setting OS parameters.
   Successfully set OS parameters.
   Set and check OS parameter completed.
   Preparing CRON service.
   Successfully prepared CRON service.
   Preparing SSH service.
   Successfully prepared SSH service.
   Setting user environmental variables.
   Successfully set user environmental variables.
   Configuring alarms on the cluster nodes.
   Successfully configured alarms on the cluster nodes.
   Setting the dynamic link library.
   Successfully set the dynamic link library.
   Fixing server package owner.
   Successfully fixed server package owner.
   Create logrotate service.
   Successfully create logrotate service.
   Setting finish flag.
   Successfully set finish flag.
   Clean SSH trust for the root permission user.
   Successfully cleaned SSH trust for the root permission user.
   Preinstallation succeeded.
   
   

2. 安装新增的主机。

   omm@plat1:/opt/software/gaussdb/script> gs_replace -t install -h plat3
   Distributing configuration to remote host.
   Successfully distributed configuration to remote host.
   Installing.
   Checking installation environment on nodes.
   Successfully checking installation environment on nodes.
   Installing applications on nodes.
   Installation is completed.
   ==============================
   Time statistics:
           Install replacement nodes: 9s
   total: 9s

3. 配置新增的主机。

   omm@plat1:/opt/software/gaussdb/script> gs_replace -t config -h plat3
   Check cluster status for replace.
   Check the status of ETCD cluster.
   Successfully check the status of ETCD cluster.
   Successfully check cluster status.
   Filter out all valid hosts for replacing.
   Distributing configuration to remote host.
   Successfully distributed configuration to remote host.
   Configuring
   Stopping replace instances.
   Successfully stopped replace instances.
   Configuring replacement instances.
   Config replace instances.
   Successfully config replace instances.
   Config standby DN of new instances.
   .......67s
   Config standby DN of new instances successfully.
   Successfully configured replacement instances.
   Configuration succeeded.
   ==============================
   Time statistics:
           Config replacement nodes: 95s
   total: 95s

4. 启动新增的主机。

   omm@plat1:/opt/software/gaussdb/script> gs_replace -t start -h plat3
   Starting.
   ==============================
   ..
   Start cm agent on new nodes.
   Successfully start cm agent for new nodes.
   Starting the cluster.
   ......
   Successfully started instance process. Waiting to become Normal.
   ==============================
   Successfully started cluster.
   ==============================
   Time statistics:
           Start replacement nodes: 35s
   total: 35s