Tech Note: Using Brocade Access Gateway Device-Based Mapping in VMware ESX Server Environments (June 2010)

DATA CENTER

Tech Note:

Using Brocade Access Gateway Device-Based

Mapping in VMware ESX Server Environments

INTRODUCTION

Brocade

Access Gateway (AG) mode eliminates traditional heterogeneous switch-to-switch interoperability

challenges by utilizing N_Port ID Virtualization (NPIV) standards to present Fibre Channel server connections

as logical devices to SAN fabrics.

Several server connections can be mapped to a single connection to the core fabric. A recent advanced

feature of the Brocade AG enables each logical server (virtual machine, or VM) to be mapped to the uplink

port using its virtual World Wide Name (WWN, also called NPIV ID). This feature, called device-based

mapping, allows VMs to have the same properties as physical servers. Therefore, VMs on a single physical

server can now be connected to multiple fabrics through Brocade Access Gateway, while retaining all their

fabric services. With device mapping, VMs are free to move to any physical server and still retain their

zoning and fabric-based properties (such as QoS, security, and zoning).

Figure 1 illustrates this concept. Note that SAN A and B in the figure could also represent two virtual SANs

that are part of same physical SAN.

Figure 1. Device-based map allows virtualization of physical servers

This Tech Note describes expected vs. observed behavior when using device-based mapping in Access

Gateway mode in VMware ESX Server environments. It describes best practices for this configuration and

provides recommendations for minimizing the impact of the expected behavior when it occurs.

In summary, NPIV and device-based mapping is a new Brocade Fabric OS

(FOS) feature that allows a

separation of virtual infrastructure from the underlying physical infrastructure. It represents yet another

step in the virtualization of the physical data center infrastructure.

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DATA CENTER Tech Note: Using Brocade Access Gateway Device-Based Mapping in VMware ESX Server Environments INTRODUCTION Brocade® Access Gateway (AG) mode eliminates traditional heterogeneous switch-to-switch interoperability challenges by utilizing N_Port ID Virtualization (NPIV) standards to present Fibre Channel server connections as logical devices to SAN fabrics. Several server connections can be mapped to a single connection to the core fabric.
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DATA CENTER TECH NOTE VMWARE ESX SERVER BEHAVIOR NOTE: Process ID (PID) is a Fiber Channel term that refers to a 24-bit switch-assigned ID used throughout the fabric to route frames from a source to a destination. Upon detection of I/O failure on the ESX Server base physical ports, all virtual port I/O traffic uses the base ESX Server PID instead of the virtual port PID. One symptom of this behavior is that VMs cannot use the path defined by the device mapping.
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DATA CENTER TECH NOTE Once ESX Server reverts to using the physical port ID, it does not revert back to using the virtual port ID unless the virtual port is rebooted. As shown in Figure 4, when the primary fabric link is back online, the ESX Server is still using its physical port ID for all I/O traffic. Figure 4.