ORACLE 10g RAC [Cssclnt][1]clsssinitnative:connect failed, RC 9

"[Cssclnt][1]clsssinitnative:connect failed, RC 9" is a common problem encountered in Oracle RAC, mainly during the installation process and during startup. Often the Css*.log file in the $ora_crs_home/log/
The main meaning of this error is that the CSSD process connection between the RAC nodes fails, the communication is not effective, the CSSD process communication between the RAC nodes is done through the private network and the voting disk, both of which must be able to communicate and access properly to ensure that the CSSD process can communicate properly. The CSSD process communication between the RAC node servers uses the IPC protocol (the communication protocol between the internal processes). Because the CSSD process of the RAC node server cannot communicate, the clusterware of all nodes cannot be started.

When you receive this error, you can take the following processing methods:
1). Ensure that all networks, including private networks, public networks, can ping properly.
2). Make sure that the firewall for all the RAC node servers is off.
3). Ensure that all RAC nodes are properly connected to the storage and have normal access to the appropriate device for storage, for example, the device owner of the storage voting disk and OCR should be oracle:oinstall.
4). If the above is OK, consider upgrading the firmware version of the node server device (server network card, Server FC HBA card, etc.).

ORACLE 10g RAC [Cssclnt][1]clsssinitnative:connect failed, RC 9