Oracle is claiming that the demand for Real Application Clusters (RAC) in SE is low – we cannot confirm that. That is their justification for no longer permitting RAC with the Standard Edition offering (SE2) as of 19c. This means the 2019 release of SE2, or 19.3, (or 184.108.40.206 in the old version naming convention) SE2 will not support RAC. 18c does, 19c does not.
To upgrade to 19c in SE, you will have to convert your SE RAC to a single instance otherwise it will not upgrade. If RAC is essential to you then you will need to consider upgrading your SE to Enterprise Edition (EE). Of course Oracle strongly recommends you instead migrate to their Autonomous Database Cloud offering, however that is only relevant if a cloud migration was your agreed strategy and it does not orphan a significant infrastructure investment.
Some other options to consider:
Purchasing Oracle Clusterware and script your own failover to other nodes
Using Oracle OVM to cluster across multiple servers that would permit individual machine outage
Use Operating System clustering to achieve an automated failover
Use Virtual Machine replication with your own failover detection and automation
Use DBVisit Standby to maintain a replicated standby instance
These options are technically disaster recovery options that may have small outages as opposed to continuous usage that would be achieved with high availability solutions like RAC. You could also revert to not using RAC and have a single instance with a robust backup regime.
Plus there is always the option of migrating away from Oracle altogether.
Your requirements determine what solution to consider whether it be implement an alternative as listed above or upgrade to Enterprise Edition or migrate to a cloud solution. If you require continuous usage even with partial infrastructure failure, then the Enterprise Edition database (with RAC) and cloud migrations are your only true high availability options within the Oracle realm.
How long can you remain supported on your current SE with RAC ?
11gR2/220.127.116.11: Extended Paid Support until 31-Dec-2020
12c/18.104.22.168: Extended Paid Support until 31-Jul-2021
12cR2/22.214.171.124: Premier Support ends 23-Nov-2020 and there is no Extended Support announced
18c/126.96.36.199: Premier Support ends 2 years from the release of 19c to on-premises which has not happened yet but is expected to occur by end of July 2019.
It appears the 12.2 customers are at most risk here due to the support ending 23-Nov-2020 leaving you 17 months (at the time of writing) to determine and implement a strategy.
It is disappointing that Oracle keeps moving the goalposts on its technology offerings, but that is the reality whether it be Java, database or cloud offerings. Pebble IT have helped clients since 2003 in all matters of Oracle compliance, licensing, migrations, upgrades and transformations for Oracle software, infrastructure and cloud. This has included migrations to SQL Server and clustering of SQL Server where there is a more friendly attitude towards licensing in virtualisation.
Your requirements will determine what option is best for you, we are happy to work with you to help facilitate the most strategic and suitable decision considering your circumstances and requirements. Please feel free to contact us at firstname.lastname@example.org or 9460 0000 to discuss further.