[T Series]Using the Public Loop Mode for an FC Host Port Led to a Failure to Set up a Connection with the Atto 42ES HBA

Publication Date:  2012-07-19 Views:  195 Downloads:  0
Issue Description

Product and version information:

  • S5500T V100R001 V100R002
  • S5600T V100R001 V100R002
  • S6800T V100R001 V100R002
  • Application server operating system: Apple MAC OS 10.6.4 (10F2554)
  • HBA: Atto Celerity FC-42ES (driver version: 3.4.4)

When the FC host port on the storage device was directly connected to the Atto 42ES HBA, and the FC host port Mode was Public Loop, the FC host port Running Status was Offline on the ISM.

Alarm Information
None
Handling Process

Set the FC host port Mode to Point to Point.
 1. Log in to the ISM and expand the storage node, and then choose Device Info > Ports in the navigation tree.
 2. Select the FC host port and right-click it.
 3. Choose Modify in the shortcut menu.
 4. In the Modify FC Port dialog box, set Mode to Point to Point.

Root Cause

The default Atto Celerity FC-42ES topology mode is "P2P preferred, then loop". When it was setting up a connection to the storage device, we recorded the interaction process on the link by using the Finisar packet catcher.Figure1 shows the record.
    Figure 1 Interaction process on the link

After analyzing the process, we found out that after the storage device sent a LIP command (a control command in the FC protocol to notify the other party of the FC host port Mode being Public Loop), Atto sent a NOS command (a control command in the FC protocol to terminate the current topology negotiation). It is concluded that the HBA has defects in negotiating topology modes.

Suggestions
When connecting a storage device to ATTO Celerity FC-42ES through a DAS network, set the FC host port Mode to Point to Point.

END