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error. This also applies to using Fabric OS commands for device mapping. You could also map

several devices to a new port group and then create the group without error. You can also remove one

device, and then remove another device without error.

Enabling device mapping for individual virtual machines (VMs) running on a VMware ESX server

connected to an F_Port can redirect I/O traffic for these VMs, provided the server is configured to use

Raw Device Mapped storage. All traffic will originate from a VM’s WWN and will follow any mapping

configured for the WWN. If anything interrupts the virtual port’s connection for the VM, such as a

failover port being used because a port goes offline, traffic will originate from the ESX server’s base

device port ID and not the VM’s port ID. If there are any additional disruptions, the server will not

switch back to the virtual port, and the VM’s traffic will not follow the configured device mapping. Note

that this can also occur when a VM first boots, prior to any failover.

When this behavior occurs, the VM’s WWN will be properly logged in to the fabric. The WWN appears

in the output of ag --show and ag --wwnmapshow , as well as on the switch. The output from the

portperfshow command displays all traffic on the port to which the ESX server port is mapped (base

PID).

To configure WWN mapping on VMware ESX systems, use the following steps.

1. Make sure that virtual world wide port names (VWWPN) of virtual machines (VMs) are mapped to

the correct port group (or N_Port). Map all VWWPNs to N_Ports to avoid confusion.

2. Make sure all VWWPNs are mapped for LUN access for array-based targets.

3. Make sure to include all VWWPNs in the zone configuration.

4. Reboot the VM.

5. Zone the server’s physical port to the storage device.

6. Check the traffic that originates from the virtual node PID (VN PID). If the configuration is correct,

traffic will flow from the VN PID.

For additional information on using device mapping for connecting VMware systems, refer to the

Technical Brief How to Configure NPIV on VMware ESX Server 3.5 :

http://www.brocade.com/downloads/documents/brocade_vmware_technical_briefs/

Brocade_NPIV_ESX3.5_WP.pdf.

When using device mapping with VMware, the base device initiates PLOGI and PRLI to the target,

and then discovers the LUN. The virtual device also initiates a PLOGI and PRLI to the target, but LUN

discovery does not occur. Therefore, when the device-mapped port is toggled and failover or failback

takes place, traffic will resume from the base device. One of the following actions is recommended

when using device mapping with VMware:

• Make sure targets can be reached by the base device so that I/Os can resume if the mapped device

fails over and I/Os move over to the base PID.

• Reboot the server so that it initializes and uses configured device mapping.

Considerations for Access Gateway mapping

This section outlines considerations and limitations for Access Gateway mapping types.

44 Access Gateway Administrator's Guide

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