The SQL resource is the SQL Service. The resources that you see in the cluster administrator map to services, or devices on the servers. When the cluster fails over it simply stops the SQL Service on one node and starts the service on the other node.
If disks take a long time to fail over that’s because the servers are having a problem changing the ownership of the disks from one node to another. This is usually due to something on the old node still trying to do something with the disk on that machine.
If SQL is taking a long time to come online that should be shown in the SQL ERRORLOG file. You should look in there to see why that disk isn’t coming online.