A shape is a resource profile that specifies the number of OCPUs and the amount of memory to be allocated to an instance in Compute Classic. The shape determines the type of disk drive that your instance uses. If you select a general purpose or high-memory shape, a hard-disk drive is used. If you select a high-I/O shape, an NVM Express solid-state drive is used. High-I/O shapes also determine the size of the root disk.
Note: High-I/O shapes aren't available in all sites.
For more information about shapes, see About Machine Images and Shapes in Using Oracle Cloud Infrastructure Compute Classic.