Reference:https://docs.cloud.oracle.com/en-us/iaas/Content/Block/Concepts/blockvolumeperformance.htm

Explanation
Youcan create a clone from a volume using the Block Volume service. Cloning enables you to make a copy of an existing block volume without needing to go through the backup and restore process.
A cloned volume is a point-in-time direct disk-to-disk deep copyof the source volume, so all the data that is in the source volume when the clone is created is copied to the clone volume.
You can only create a clone for a volume within the same region, availability domain and tenant. You can create a clone for a volumebetween compartments as long as you have the required access permissions for the operation.
during create a clone you can do the following
If you want to clone the block volume to a larger size volume, check Custom Block Volume Size (GB) and then specifythe new size. You can only increase the size of the volume, you cannot decrease the size. If you clone the block volume to a larger size volume, you need to extend the volume's partition. See Extending the Partition for a Block Volume for more information.
If you want to change the elastic performance setting when cloning the volume, check Custom Block Volume Performance and select the elastic performance setting you want the volume clone to use. See Block Volume Elastic Performance for more information. You can also change the elastic performance setting after you have cloned the volume, see Block Volume Elastic Performance. If you leave Custom Block Volume Performance unchecked, the cloned volume will use the same elastic performance setting as the source volume.

Explanation
https://docs.cloud.oracle.com/iaas/Content/Balance/Tasks/managingcertificates.htm

Reference:https://oracle.github.io/learning-library/oci-library/L100-LAB/Autonomous_Data_Warehouse/ADW_