Fibre Channel Resiliency single FC port

[Willybobs27]

I have a FAS2040 with servers accessing via FC, currently dual fabric.

The end user wants to use a FC attached tape for backup, but still requires FC resiliency for Server access

So this means that 1 FC port will have to become an initiator, I guess for HA this would have to be done on both controllers?

I therefore believe this would reduce the current path count from 4 to 2 assuming path is available via the interconnect.

However how would I best zone such a solution for resiliency?

My thoughts are along the lines of two options:

Option 1

Controller A connected to Zone A

Controller B connected to Zone B

However in this case how would it behave on failover? Would I have to zone the FC adaptor normally in Zone B onto Zone A and visa versa?

Option 2

Single Zone with FC switches interconnected.

Can a single server have two active connections to the same FC zone, albeit to two separate FC switches?

Are my assumptions concerning the interconnect providing the additional path correct?

Are my two options viable? If so which is best?

[columbus_admin]

Hi,

     We are using option3...isn't that always the way it is?

The zones are specific to each switch, we don't do any fabric or zone stretching.  This give us three of four paths, always squeezing that extra bit out!

FilerA, port0 into switch A - host_filer-zone,FabricA

FilerB, port0 into switch A - tape_zone,FabricA

FilerA, port1 into switch B - host_filer-zone,FabricB

FilerB, port1 into Switch B - host_filer-zone,FabricB

- Scott

[scottgelb]

depends also how your hosts are setup... if you have 2 hba ports on the host then you can have each host go to both fabrics to both zones.  If you have one HBA port on the guest then that changes things. 

The interconnect is used and you can see the hosts logged in with igroup show and seeing them logged in the vtic.  that is the interconnect connection through the controller that doesn't own the lun.

[Willybobs27]

So essentially I do the following:

Fabric A - A single switch

Fabric B - A single switch

Hosts have two FC connections, one to Fabric A and one to Fabric B

NetApp A connects to Fabric A via a single FC port

NetApp B connects to Fabric B via a single FC port

Fabric A is zoned in for Hosts and NetApp A

Fabric B is zoned in for Hosts and NetApp B

Does Fabric A also have to be zoned in NetApp B and Fabric B for NetApp A?

I believe at this point I will see two paths to each NetApp controller. One direct and one via the interconnect. Is this correct?

[scottgelb]

The fabrics would stay separate. The host (needs MPIO setup) would see 2 paths. One through fabric A and the other through fabric B. Usually a zone is setup per initiator… so if there are 10 hosts, you would have 10 zones on fabric A (each zone with that host and the target port…the netapp target port in each zone).

Your MPIO setup should see both paths through fabric A/B when done and you can see the vtic login on the controller. The controller that owns the lun is the primary path and the other controller a secondary path.

[HENRYPAN2]

Good Morning Willy,

You may wish to zone Fabric A  in NetApp B and Fabric B for NetApp A for redundancy.

Good luck

Henry

[scottgelb]

I would try to keep 2 fabrics (in case of fabric failure) and have the host multipath to both fabrics (as long as hosts have 2 paths) for the redundancy.

[columbus_admin]

Henry,

    Without two ports on each filer, that is not possible without stretching the fabrics, and not practical as there is still only one physical connection to each switch.