参考官方文档：
ShutDown
Log in to the first database server as root.
Change to the OneCommand directory

cd /opt/oracle.SupportTools/onecommand

Stop the Grid Infrastructure stack on the database servers (compute nodes):

dcli -g dbs_group -l root "/u01/app/12.1.0.2/grid/bin/crsctl stop crs"

Verify that the Grid Infrastructure stack has shutdown successfully on the database servers. The following command should show no output if the GI stack has shutdown:

dcli -g dbs_group -l root "ps -ef | grep diskmo[n]"

[Optional] Disable email/SNMP alerts if applicable. If alerts will be enabled, first note the notification method in use so that it can be restored later. The following command will show the current notification method:

dcli -g cell_group -l root "su - celladmin -c \"cellcli -e list cell attributes name,notificationMethod\""

Now set the notification method to null to disable alerts:

dcli -g cell_group -l root "su - celladmin -c \"cellcli -e alter cell notificationMethod=null\""

Shutdown all the cells:

dcli -g cell_group -l root "su - celladmin -c \"cellcli -e alter cell shutdown services all \""

Power off all cells:

dcli -g cell_group -l root poweroff

Copy the /opt/oracle.SupportTools/onecommand/dbs_group to /opt/oracle.SupportTools/onecommand/dbs_group2:

cp /opt/oracle.SupportTools/onecommand/dbs_group /opt/oracle.SupportTools/onecommand/dbs_group2

Remove the “first compute node name” from the /opt/oracle.SupportTools/onecommand/dbs_group2 file (using any editor, e.g. vi).
Power off all the compute nodes (except compute node 1):

dcli -g dbs_group2 -l root poweroff

Power off the compute node #1:

poweroff

Now, both Cell Servers & Compute nodes are down for maintenance.