Welcome to Knowledge Base!

Applies to

• Brocade 8GBps Switches
• Brocade 300
• Brocade 5100

Question(s) and Answer(s)

What are Fillwords in a fibre channel environment and what does NetApp recommend they be set at?

What is the recommended Fillword setting for using 8GBps Brocade switches?

Fillwords are 4-byte words without a special task. A port sends them when it does not have to send something else. They are used to maintain the synchronization of the link.

The recommended Fillword setting is 3.

The available Fillword values are as follows:

0 | -idle-idle Sets IDLE mode in the Link Init and IDLE as the fill word (default).
1 | -arbff-arbff Sets ARB(ff) in the Link Init and ARB(ff) as the fill word.
2 | -idlef-arbff Sets IDLE mode in the Link Init and ARB(ff) as the fill word.
3 | -aa-then-ia Attempts hardware arbff-arbff (mode 1) first. If the attempt fails to go into active state, this command executes software idle-arb (mode 2). Mode 3 is the preferable to modes 1 and 2 as it captures more cases.

The difference is that '3' attempts '1' and then '2'.

Note :

• Changing fillword is a disruptive event as the port will bounce when this change is made.
• Some third-party storage vendors might require different Fillwords for their storage than
• E ports and ISL ports may require different settings depending on xWDM vendors. Contact the vendors in both of these situations.

Applies to

ONTAP

Description

The Organizationally Unique Identifier (OUI) is built into all MAC addresses and World Wide Node and Port names. The naming format used will determine which part of the name is the OUI.

Applies to

• MetroCluster
• ONTAP 8.2
• Volume has nvfail setting turned on

Issue

After a CFOD (Cluster Failover on Disaster) event:

• Servers lose connectivity to NFS mounts and need to be remounted.
• LUNs are offline

node1> vol options vol1
nosnap=off, nosnapdir=off, minra=off, no_atime_update=off, nvfail=on ,
ignore_inconsistent=off, snapmirrored=off, create_ucode=off,

Applies to

• MetroCluster
• ONTAP 9
• FlexArray

Answer

This document outlines the shared initiator and shared target configuration support with Array LUNs in a MetroCluster environment.
Sharing of Initiator and sharing of target in a MetroCluster Configuration with Array LUNs is supported starting with Data ONTAP 8.3

Note: A minimum of four target ports are required for a MetroCluster with array LUNs.

Being able to share a given FC initiator port or target ports is useful for organizations that want to minimize the number of initiator or target ports used.
For example, an organization that expects low I/O usage over an FC initiator port or target ports might prefer to share FC initiator port or target ports instead of dedicating each FC initiator port to a single target port.
However, sharing of initiator or target ports can adversely affect performance.

Supported configuration:

Supported MetroCluster for Shared Target with array LUNs:

1. 4/8-node MetroCluster configuration, where initiators are sharing target ports from the same site
2. 4/8-node MetroCluster configuration, where initiators are sharing target ports from both the local and remote site

Supported MetroCluster for Shared Initiator with array LUNs:

1. 2-node MetroCluster configuration, where initiators are shared across array target ports from the same site
2. 4/8-node MetroCluster configuration, where initiators are shared across array target ports from the same site
3. 2-node MetroCluster configuration, where initiators are shared across array target ports from both the local and remote site
4. 4/8-node MetroCluster configuration, where initiators are shared across array target ports from both the local and remote site

Additional Information

Planning a MetroCluster with array LUNs for Shared Target Ports:
Connecting a maximum of two Data ONTAP FC initiator ports to a single target port on the storage array is supported. Each target port is zoned into two FC initiator ports.

The rules for this configuration are as follows:

• Each node can share, at the most, one FC initiator port with the same target port.
• All storage arrays must be from the same vendor and model family.
• The best practice for zoning is to have each FC initiator-target port pair in a separate zone (1:1).

Example configuration: Shared target ports:

4/8-node MetroCluster where initiators are sharing target ports from the same site.
The below diagram shows a 4-node MetroCluster configuration, where initiators are sharing target ports from the same site with the respective zoning information

For 8-Node MetroCluster, to configure the switch zoning, you can use the zoning examples of the above 4-node MetroCluster for the first DR group. To configure zoning for the second DR group, follow the same example and requirements for the FC initiator ports and array LUNs belonging to the controllers in the second DR group.

4/8-node MetroCluster where initiators are sharing target ports from both local and remote site.
The below diagram shows a 4-node MetroCluster configuration where initiators are sharing target ports from both local and remote site with the respective zoning information

For 8-Node MetroCluster, to configure the switch zoning, you can use the zoning examples of the above 4-node MetroCluster for the first DR group. To configure zoning for the second DR group, follow the same example and requirements for the FC initiator ports and array LUNs belonging to the controllers in the second DR group.

Planning a MetroCluster with array LUNs for Shared Initiator:
Connecting an FC initiator port on a Data ONTAP system to up to four target ports on storage arrays is supported.
The rules for this configuration are as follows:

• All storage arrays must be in the same vendor model family.
  Storage arrays in the same family share the same performance and failover characteristics.
  For example, storage arrays with different architectures would be in different families even though other characteristics might be the same. See the FlexArray Virtualization Implementation Guide for Third-Party Storage for details about the models in the storage array families for your vendor.
• A single FC initiator port can connect to up to four target ports on multiple storage arrays.
• The best practice zoning recommendation is to put each FC initiator-target port pair in a separate zone (1:1), even if the same FC initiator is talking to multiple target ports

Example configuration: Shared FC initiator ports

2-node MetroCluster where initiators are shared across array target ports from the same site
The below diagram shows a 2-node MetroCluster configuration where initiators are shared across target ports of the arrays in the same site with the respective zoning information.

4/8-node MetroCluster where initiators are shared across array target ports from the same site
The below diagram shows a 4-node MetroCluster configuration where initiators are shared across array target ports from the same site with the respective zoning information.

For 8-Node MetroCluster, to configure the switch zoning, you can use the zoning examples of the above 4-node MetroCluster for the first DR group. To configure zoning for the second DR group, follow the same example and requirements for the FC initiator ports and array LUNs belonging to the controllers in the second DR group.

2-node MetroCluster where initiators are shared across array target ports from both local and remote site
The below diagram shows a 2-node MetroCluster configuration where initiators are shared across array target ports from both local and remote sites with the respective zoning information.

4/8-node MetroCluster where initiators are shared across array target ports from both local and remote site
The below diagram shows a 4-node MetroCluster configuration where initiators are shared across array target ports from both local and remote sites with the respective zoning information.

For 8-Node MetroCluster, to configure the switch zoning, you can use the zoning examples of the above 4-node MetroCluster for the first DR group. To configure zoning for the second DR group, follow the same example and requirements for the FC initiator ports and array LUNs belonging to the controllers in the second DR group.