Overview of dual_fabric mode

How target ports provide access to LUNs

The dual_fabric mode is supported on FAS270c clusters only. It is not supported on other systems.

The FAS270c cluster consists of two storage systems integrated into a disk shelf. Each storage system has two Fibre Channel ports. The orange-labeled port operates as a Fibre Channel target port after you license the FCP service and reboot the storage system. The blue-labeled port connects to the internal disks, enabling you to connect additional disk shelves to an FAS270c cluster. The Fibre Channel target port of each FAS270c storage system in the cluster supports three virtual ports:

Virtual local port, which provides access to LUNs on the local FAS270c
Virtual standby port, which is not used
Virtual partner port, which provides access to LUNs on the partner node
Note
For switched configurations, dual_fabric mode requires switches that support public loop.

Configurations with the FAS270c require that multipathing software be installed on the hosts.

The following figure shows the recommended production configuration, in which a multi-attached host accesses a FAS270c cluster.

What happens during a failover

The virtual ports enable the FAS270c cluster, which has only one physical target FCP port per node, to support traffic for both nodes in the cluster. For example, if Switch 1 fails, the multipathing software on the host uses HBA 2 and Switch 2 to access the partner virtual port on Node B. The partner virtual port forwards the requests to Node A. When the cluster is in a takeover state (Node B takes over for Node A), Node B uses the partner virtual port to directly serve data for LUNs on Node A.

How Data ONTAP displays target port information

State of Fibre Channel Port 1

When the FAS270c port labeled Fibre Channel 1 operates as a SAN target, the sysconfig -v command shows this port as a Fibre Channel Target Host Adapter installed in slot 0. The following example shows sysconfig -v output for a FAS270c in SAN target mode.

fas270> sysconfig

        NetApp Release 7.1: Mon June 25 02:20:04 PDT 2005

        System ID: 0084165669 (filer_1); partner ID: 0084165671 (filer_2)

        System Serial Number: 379589 (filer_1)

        slot 0: System Board

                Processors:         2

                Processor revision: B2

                Processor type:     1250

                Memory Size:        1022 MB

        slot 0: FC Host Adapter 0b

                14 Disks:            952.0GB

                1 shelf with EFH

        slot 0: Fibre Channel Target Host Adapter 0c

        slot 0: SB1250-Gigabit Dual Ethernet Controller

                e0a MAC Address:    00:a0:98:00:d5:90 (100tx-fd-up)

                e0b MAC Address:    00:a0:98:00:d5:91 (auto-unknown-cfg_down)

        slot 0: NetApp ATA/IDE Adapter 0a (0x00000000000001f0)

                0a.0                 122MB

Target virtual ports

FCP commands display three virtual ports for the one FAS270c physical target FCP port. For example, the fcp show adapter command shows the target FCP port as an adapter in slot 0c. The local virtual port is 0c_0, the standby virtual port is 0c_1, and the partner virtual port is 0c_2.

The following output example shows how the fcp config command displays virtual ports when the storage system is in dual_fabric mode and the cluster is in normal operation.

FAS270> fcp config

0c:   ONLINE <ADAPTER UP>  Loop  Fabric

        host address 0100da

        portname 50:0a:09:81:85:c4:45:91  nodename 50:0a:09:80:85:c4:45:91

        mediatype loop  partner adapter 0c

0c_0: ONLINE Local

        portname 50:0a:09:81:85:c4:45:91  nodename 50:0a:09:80:85:c4:45:91

        loopid 0x7 portid 0x0100da

0c_1: OFFLINE Standby

        portname 50:0a:09:81:85:c4:45:88  nodename 50:0a:09:80:85:c4:45:88

        loopid 0x0 portid 0x000000

0c_2: ONLINE Partner

        portname 50:0a:09:89:85:c4:45:88  nodename 50:0a:09:80:85:c4:45:88

        loopid 0x9 portid 0x0100d6