US Patent 7787452 Isolation of unverified devices in a SAS expander

When a new device is attached to a SAS expander, malfunctioning devices can cause many BCNs to be generated, which in turn can cause excessive re-discovery processes to be performed by initiators in a storage network. Therefore, the isolation of devices from the storage network until they can be validated as healthy is disclosed. Any device malfunctions during this time of isolation do not cause BCNs to be generated and do not cause re-discovery processes to be performed. Once the device is validated (via a port-test-before-insertion approach) and found to be healthy, the fabric is notified via a BCN, and the device can be made visible to the network.