question

anyone dears

Oracle Real Application Cluster (RAC) is a solution by Oracle to help customers achieve high throughputs by having many instances accessing one database storage (Shared-all architecture pattern).

While Oracle RAC can also be used for high availability on-premises, Oracle RAC alone cannot be used for high availability in the cloud as it only protects against instance level failures and not against Rack-level or Data center-level failures. For this reason, Oracle recommends using Oracle Data Guard with your database (whether single instance or RAC) for high availability. Customers generally require a high SLA for running their mission critical applications.

Oracle RAC is currently not certified or supported by Oracle on Azure. However, Azure offers features such as Azure offers Availability Zones and planned maintenance windows to help protect against instance-level failures. In addition to this, customers can use technologies such as Oracle Data Guard, Oracle GoldenGate and Oracle Sharding for high performance and resiliency by protecting their databases from rack-level as well as datacenter-level and geo-political failures.

When running Oracle Databases across multiple availability zones in conjunction with Oracle Data Guard or GoldenGate, customers are able to get an uptime SLA of 99.99%. In Azure regions where Availability zones are not yet present, customers can use Availability Sets and achieve an uptime SLA of 99.95%.

NOTE: You can have a uptime target that is much higher than the uptime SLA provided by Microsoft.

You may also find these docs helpful :

https://docs.microsoft.com/en-us/azure/virtual-machines/workloads/oracle/oracle-reference-architecture#oracle-rac-in-the-cloud
https://techcommunity.microsoft.com/t5/data-architecture-blog/oracle-rac-on-azure/ba-p/1185410