Storage nodes and devices are physical objects in the system. Storage pools are entirely logical: groups for volumes, logical volumes and their snapshots.
In this video:
Pool limits: total capacity and quality of service caps
Each storage pool auto-creates one storage class
Storage class settings: encryption, compression, fabric (TCP or RDMA)
The one-to-one relationship between a PVC and the volume
See how it works: https://www.simplyblock.io
Chapters 0:00 Storage pools
0:39 Inside a storage pool
1:49 Storage classes
3:13 PVCs and volumes