Enabling or Disabling Multipathing on a Per-Port Basis

Multipathing can be enabled or disabled on specific Fibre Channel Host Bus Adapter (HBA) controller ports. If you enable multipathing on a specific HBA port controller port, all supported devices connected to that controller port will be enabled for multipath operation.

Port Configuration Considerations

Before you start configuring the software by port, consider the following:

• FC global and per-port multipath settings are specified in the file /kernel/drv/fp.conf.

  Per-port multipath settings have priority over the global setting. Therefore, if global multipathing is enabled but a specific port has been disabled for multipathing, the port will not be available in the multipathing configuration. Conversely, even if global multipathing has been disabled, specific ports may be enabled for multipathing if they are listed in the appropriate driver.conf file.

• Load balancing is controlled by the global load-balance property in the/kernel/drv/scsi_vhci.conf file and is not controlled on a per-port basis.

• If a device has more than one path to the host, all paths to the device must be configured with multipathing enabled or disabled.

• Configuring multipathing by port enables the multipathing software to coexist with other multipathing solutions like Symantec (VERITAS) Dynamic Multipathing (DMP), or EMC PowerPath. However, devices and paths should not be shared between the multipathing software and other multipathing solutions.

How to Configure Multipathing by Port

The following procedure applies to both SPARC based and x86 based systems.

Depending on how many ports you want the multipathing software to control, you can enable or disable multipathing globally or for specified ports.

1. Become superuser.
2. Determine the HBA controller ports that you want the multipathing software to control.

   To list the available devices, perform an ls -l command on the /dev/cfg directory. The following example shows the ls -l command output.

   # ls -llrwxrwxrwx  1 root  root  50 Jan 29 21:33 c0 -> 
        ../../devices/pci@7c0/pci@0/pci@1/pci@0/ide@8:scsi
   lrwxrwxrwx  1 root  root  61 Jan 29 21:33 c1 ->
        ../../devices/pci@7c0/pci@0/pci@1/pci@0,2/LSILogic,sas@1:scsi
   lrwxrwxrwx  1 root  root  61 Jan 29 21:33 c2 -> 
        ../../devices/pci@7c0/pci@0/pci@1/pci@0,2/LSILogic,sas@2:scsi
   lrwxrwxrwx  1 root  root  53 Jan 29 21:33 c3 -> 
        ../../devices/pci@7c0/pci@0/pci@9/LSILogic,sas@0:scsi
   lrwxrwxrwx  1 root  root  54 Apr 16 20:28 c5 ->
        ../../devices/pci@780/pci@0/pci@8/SUNW,qlc@0/fp@0,0:fc
   lrwxrwxrwx  1 root  root  56 Apr 16 20:28 c6 -> 
        ../../devices/pci@780/pci@0/pci@8/SUNW,qlc@0,1/fp@0,0:fc

   ---

   Note - Controllers c5 and c6 are ports A and B on a dual-port FC HBA. Controllers c1 and c3 are single port SAS HBA ports. Controller c2 is the internal SAS controller in Oracle's Sun Fire T2000 server.

   ---

   Determine the port or ports for which you want to explicitly enable or disable multipathing.

3. Select one of the following to enable or disable specific FC HBA ports:

   • For each FC HBA port that is to be enabled in the /kernel/drv/fp.conf file, add the following line:

     name="fp" parent="parent-name" port=port-number mpxio-disable="no";

     where parent-name is the port device name, and port-number is the FC HBA port number.

     For example, the following entries disable multipathing on all FC HBA controller ports except for the two specified ports:

     mpxio-disable="yes";
     name="fp" parent="/pci@6,2000/SUNW,qlc@2" port=0 mpxio-disable="no";
     name="fp" parent="/pci@13,2000/pci@2/SUNW,qlc@5" port=0 mpxio-disable="no";

   • For each FC HBA port that is to be disabled, add the following line:

     name="fp" parent="parent-name" port=port-number mpxio-disable="yes";

     For example:

     name="fp" parent="/pci@6,2000/SUNW,qlc@2" port=0 mpxio-disable="yes";

4. Start the reboot and configuration process.

   # stmsboot -u

   You are prompted to reboot. During the reboot, the /etc/vfstab file and your dump device configuration are updated to reflect any device name changes.

5. (Optional) After the reboot, if necessary, configure your applications to use new device names as described in Multipathing Considerations.