Patching Exadata Cloud Services
First of all there are three different versions of Exadata cloud services
Exadata Cloud Classic (Gen -1)
Exadata Cloud on OCI (Gen-2)
Exadata Cloud at Customer
Please check out this Blog Post to understand the differences
All three have different patch levels that are published.
Oracle has a number of notes to help you understand which patches are appropriate for which type of Exadata Cloud System. You will need an Oracle support ID to view these.
Exadata Cloud Service Software Versions (Doc ID 2333222.1)
How to update the Exadata Image (OS) in the Exadata Cloud Service (OCI-C) (Doc ID 2380001.1)
With the latest version of the patchmgr software i.e 19.2 there is no longer an option to use the dbnode.sh script to patch a system directly. Patchmgr must be used from a remote system to complete the patching process. This also requires ssh equivalence for root to be set up between the driving system and the Exadata db nodes to be patched.
The patchmanager version 19.2 can be used to patch any version of the Exadata software including the cloud versions mentioned here.
You can download the latest version of Patchmanager here
Please note that Oracle them selves will take care of patching the Storage layer, Infiniband and the Dom0 or hypervisor of the systems. As they do this in a rolling fashion you will be made aware of the patching taking place but there will not be a interruption of service to the database as a whole since one db node will go offline at a time. However if you have dedicated services to individual nodes of your RAC cluster then you will not have the requisite High availability setup and you may suffer some disruption. for this reason it is essential to use services that can be migrated between nodes as required rather than sids.
For DomU it is important to have full backups of all databases in place. please ensure that your grid software versions and DB versions are compatible with the image you are trying to apply. Please not that the images for the Exadata cloud service are provided in the notes given above you should not try to use any version that is not yet compatibility tested . For example version 19 is only available for Gen 2 cloud at present . It is not available for the Gen 1 cloud or Exadata Cloud at customer which must remain on version 18