以主备集群为例
1.扩充redo日志（已执行可直接进行跳过此步骤）
登录DM管理工具
登录SYSDBA用户执行
alter database resize logfile ‘DMDB01.log’ to 2048;
alter database resize logfile ‘DMDB02.log’ to 2048;

2.清理服务器缓存
登录root用户
free -h //查看内存和缓存
watch free-h //实时查看内存和缓存
sync //先把buffe中的数据写入到硬盘中
echo 3 > /proc/sys/vm/drop_caches //清除缓存
3.切换单库进行迁移
备库守护进程与服务停止
登录101.72.29.51
cd /home/dmdba/dmdbms/bin
./DmWatcherServiceWATCHER2 stop
./DmServiceDMSERVER2 stop
登录101.72.29.61
cd /home/dmdba/dmdbms/bin
./DmMonitorServiceDMMONITOR stop
./DmWatcherServiceDMWATCHER3 stop
./DmServiceDMSERVER3 stop
登录101.72.29.41
cd /home/dmdba/dmdbms/bin
./DmWatcherServiceDMWATCHER1 stop
./DmServiceDMSERVER1 stop
cd /home/dmdba/dmdbms/data/DMDB/
mv dmmal.ini dmmalstop.ini
vim dm.ini
页面中输入/INI
定位到MAL_INI 将参数修改为0
:wq保存并退出
vim dmarch.ini
截止[ARCHIVE_LOCAL]之前的所有行不包括此行前面加入#号，行内容变为蓝色即成功
:wq保存并退出
cd /home/dmdba/dmdbms/bin
./DmServiceDMSERVER1 start
./disql
SYSDBA/SYSDBA
登录成功后分别执行以下语句
alter database mount;
如提示当前数据库处于mount状态为正常现象可直接执行下一步
alter database normal;
alter database open;
执行成功后Ctrl+c结束
./DmServiceDMSERVER1 restart
进行数据迁移
迁移完成后进行如下操作
登录101.72.29.41
cd /home/dmdba/dmdbms/data/DMDB/
mv dmmalstop.ini dmmal.ini
vim dm.ini
页面中输入/INI
定位到MAL_INI 将参数修改为1
:wq保存并退出
vim dmarch.ini
截止[ARCHIVE_LOCAL]之前的所有行不包括此行前面#号进行删除
:wq保存并退出

cd /home/dmdba/dmdbms/bin
./DmServiceDMSERVER1 restart
./disql
SYSDBA/SYSDBA
分别执行以下语句
alter database mount;
alter database parmary;
alter database open;
ctrl+c结束

主库备份
cd /home/dmdba/dmdbms/bin
./DmServiceDMSERVER1 stop
su dmdba --切换数据库用户，否则备份失败
cd /home/dmdba/dmdbms/bin
./dmrman ctlstmt=“backup database ‘/home/dmdba/dmdbms/data/DMDB/dm.ini’ full to backup20221024 backupset ‘/home/dmdba/dmdbms/data/DMDB/backup20221024’”

发送到备库
su root --切换管理员用户，否则传输失败
scp -r /home/dmdba/dmdbms/data/DMDB/backup20221024/ 101.72.29.51:/home/dmdba/dmdbms/data/DMDB
scp -r /home/dmdba/dmdbms/data/DMDB/backup20221024/ 101.72.29.61:/home/dmdba/dmdbms/data/DMDB

登录101.72.29.51/101.72.29.61（以下还原操作只在5和6上面进行）
授权到dmdba用户
chown -R dmdba.dinstall /home/dmdba
切换dmdba用户执行
su dmdba
cd /home/dmdba/dmdbms/bin

还原
./dmrman ctlstmt=“restore database ‘/home/dmdba/dmdbms/data/DMDB/dm.ini’ from backupset ‘/home/dmdba/dmdbms/data/DMDB/backup20221024’”
恢复
./dmrman ctlstmt=“recover database ‘/home/dmdba/dmdbms/data/DMDB/dm.ini’ from backupset ‘/home/dmdba/dmdbms/data/DMDB/backup20221024’”
更新
./dmrman ctlstmt=“recover database ‘/home/dmdba/dmdbms/data/DMDB/dm.ini’ update db_magic”
还原完成后进行服务启动
连101.72.29.41
cd /home/dmdba/dmdbms/bin
./DmServiceDMSERVER1 start
./DmWatcherServiceDMWATCHER1 start
连101.72.29.51
cd /home/dmdba/dmdbms/bin
./DmServiceDMSERVER2 start
./DmWatcherServiceDMWATCHER2 start
连101.72.29.61
cd /home/dmdba/dmdbms/bin
./DmServiceDMSERVER3 start
./DmWatcherServiceDMWATCHER3 start
./DmMonitorServiceDMMONITOR start