How to Build a High‑Availability Oracle RAC on Oracle Cloud with Flex ASM

The article, based on a live presentation by Wang Heshong, provides a step‑by‑step tutorial for deploying an Oracle Real Application Clusters (RAC) environment on Oracle Cloud, emphasizing high availability and the new Flex ASM architecture introduced in Oracle 12c.

1. Oracle Cloud Account and Access

Apply for a free personal test account at https://www.oracle.com/cn/cloud/free/; email verification and a credit‑card supporting international transactions are required.

Login URLs include the generic console https://cloud.oracle.com/ and region‑specific consoles such as https://console.ap-tokyo-1.oraclecloud.com, https://console.ap-seoul-1.oraclecloud.com, and https://console.us-phoenix-1.oraclecloud.com.

2. Creating the Virtual Cloud Network (VCN)

Use the VCN wizard, ensuring inbound and outbound security rules are correctly configured. Screenshots illustrate the VCN creation process.

3. Generating SSH Keys

Generate an RSA key pair with tools like Xshell; the public key must be saved for later upload to the cloud instance.

4. Provisioning the RAC Cluster

Select a VM shape of at least Standard2.2 and set the node count to 2.

Upload the previously generated SSH public key.

After creation, the public IP addresses of the nodes are displayed in the cluster details.

5. Configuring SSH Access

Connect to each node via SSH, then switch to the oracle user with sudo su - oracle.

6. Flex ASM Overview

Oracle 12c introduces two node types:

Hub (center) nodes – connect via a private network and have direct access to shared storage, OCR, and voting disks.

Leaf nodes – lightweight nodes that communicate only through hub nodes and cannot access shared storage directly.

Flex ASM separates ASM instances from database instances, allowing the database to remain accessible even if an ASM instance on a hub node fails.

7. Flex ASM Hands‑On Experiments

Verify cluster status with crsctl check cluster.

Check ASM instance status on both nodes using srvctl status asm.

Confirm Flex mode is enabled: asmcmd showclustermode should return "Flex mode enabled - Direct Storage Access".

Inspect detailed ASM configuration with srvctl status asm -detail and srvctl config asm -detail.

8. High‑Availability Service Configuration

Create a failover service for a specific PDB (e.g., PDB1_WHS) using:

srvctl add service -d whs1 -s ser_whs_pdb1 -r whs11,whs12 -P basic -e select -m basic -z 180 -w 5 -pdb PDB1_WHS

Start the service with srvctl start service -d whs1 -s ser_whs_pdb1 and verify its status.

9. Connection String and Session Verification

A TNS entry is defined as:

(DESCRIPTION=
  (ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.45)(PORT=1521))
  (CONNECT_DATA=
    (SERVER=DEDICATED)
    (SERVICE_NAME=ser_whs_pdb1)
  )
)

Connect with sqlplus test/test@45_pdb_whs, then query v$instance to see which node the session is using. After stopping an instance on node 1, the session automatically migrates to node 2, demonstrating Transparent Application Failover (TAF).

10. Common Q&A

Oracle Cloud is currently the only officially supported public cloud for Oracle databases; other clouds can host Oracle but lack official support.

For migrating a single‑instance database to the cloud, use Data Guard to replicate data and then fail over to the RAC.

Convert a traditional RAC to Flex ASM by using the ASMCA GUI to convert ASM, then run crsctl set cluster mode flex as root and restart the cluster.

Enterprise cloud adoption should prioritize non‑core systems; core systems may retain on‑premises backup.

Typical migration pitfalls involve private network configuration; recommended migration tools include Data Guard, Oracle GoldenGate, Data Pump, and XStream.

Oracle Cloud VMs provide built‑in virus scanning, patch management, IP/port access controls, and SSH key audit capabilities.

Overall, the tutorial demonstrates a complete workflow—from cloud account provisioning to RAC cluster creation, Flex ASM utilization, high‑availability service setup, and practical troubleshooting—equipping readers with the knowledge to deploy resilient Oracle databases on Oracle Cloud.