A first class disk (FCD) provides storage life-cycle management on virtual disks as a disk-as-a service or as EBS-like disk storage that allows you to create and manage disks independently of vSphere virtual machines.
A first class disk has its own life-cycle management capabilities that operate independently from a VM. One way that a first class disk differs from an independent persistent disk, is that you can use a first class disk to create and manage snapshots independent of a VM.
You can create a new vRealize Automation Cloud storage profile to support either first class disk capabilities or standard disk capabilities.
Support for Disk as a Service capabilities with the ability to create a First Class Disk (FCD) object independently without a Virtual Machine. Also provides the ability to Create, Edit, Delete, and List FCD objects through the APIs. VMware has included day-2 actions that allow adding disk, attach/detach, and resize. Disk snapshots lifecycle management is included with create, delete, restore operations.