VMware ESXi and vSphere Cluster Management

FCoE Adapters Explained for VMware ESXi

Learn how hardware and software FCoE adapters connect VMware ESXi hosts to Fibre Channel storage over Ethernet, including DCB, FIP, compatibility, VMFS, and troubleshooting.

Fibre Channel over Ethernet (FCoE) lets a VMware ESXi host access Fibre Channel storage by transporting Fibre Channel frames across an Ethernet network. This approach can combine ordinary Ethernet networking and Fibre Channel storage connectivity in a converged infrastructure design.

This lesson explains FCoE adapters, the difference between hardware and software implementations, the required Ethernet and SAN components, storage presentation, compatibility planning, and common troubleshooting steps. It assumes basic knowledge of ESXi storage, Fibre Channel SANs, Ethernet, LUNs, and VMFS datastores.

What Is Fibre Channel over Ethernet?

FCoE means Fibre Channel over Ethernet. Fibre Channel (FC) is a storage networking technology commonly used to connect servers to storage arrays through a Storage Area Network (SAN). FCoE preserves Fibre Channel storage communication while using Ethernet as the physical network transport.

In a simplified path, an ESXi host sends Fibre Channel traffic to an FCoE adapter. The adapter encapsulates or processes the Fibre Channel frames for Ethernet transport. An FCoE-capable Ethernet fabric carries the traffic to a Fibre Channel fabric, gateway, or directly connected storage design, depending on the supported architecture.

FCoE is not the same as carrying storage traffic through an ordinary IP network:

FCoE: transports Fibre Channel frames over Ethernet and retains Fibre Channel concepts such as Fibre Channel identities, zoning, and SAN access controls.
iSCSI: transports SCSI storage commands over TCP/IP.
NFS: provides file-based storage access over a network, usually through IP and NFS protocols.

Therefore, an Ethernet cable does not automatically make a network suitable for FCoE. The adapter, switches, configuration, and storage environment must support FCoE services and the required traffic behavior.

Why Organizations Use FCoE

FCoE is primarily a converged networking technology. Convergence means that one Ethernet-based physical infrastructure can carry both standard Ethernet traffic and Fibre Channel storage traffic, when the design supports both workloads.

Fewer physical cables may be required between servers and network infrastructure.
Host designs may use fewer network and storage ports.
Converged switches can reduce separate switch infrastructure.
Rack layouts may become less complex.
Fewer devices and connections can potentially reduce power and cooling requirements.

These are design benefits, not automatic results. They depend on compatible adapters, switches, transceivers, Fibre Channel components, storage arrays, and carefully configured end-to-end traffic policies. A poorly designed converged network can create a larger shared failure domain and make troubleshooting more complex.

FCoE in a VMware ESXi Environment

ESXi uses an FCoE adapter to present Fibre Channel storage connectivity to the host. The adapter may be a physical hardware adapter, commonly a Converged Network Adapter (CNA), or a software FCoE implementation that relies on a supported physical NIC.

The high-level data path is:

The ESXi host uses a supported FCoE-capable adapter or NIC.
The adapter connects to an Ethernet switch that supports the required FCoE and Data Center Bridging features.
The Ethernet fabric carries the Fibre Channel frames toward the Fibre Channel fabric, gateway component, or supported storage connection.
The storage array registers the ESXi host and presents one or more LUNs.
ESXi rescans its storage adapters and discovers the devices and paths.
A discovered LUN can be formatted with VMFS to create a datastore, or an existing VMFS datastore can be mounted when the design requires it.

FCoE provides the transport and connectivity. It does not by itself create a datastore or authorize access to a LUN. SAN zoning, array host groups, LUN masking, ESXi discovery, and datastore decisions remain separate configuration tasks.

Hardware FCoE Adapters and CNAs

A hardware FCoE adapter is a physical adapter with built-in Ethernet and Fibre Channel/FCoE functionality. It is commonly called a Converged Network Adapter (CNA) because it combines Ethernet networking and storage networking capabilities on one physical adapter.

A CNA can expose Ethernet networking functions and FCoE storage functions through the same physical card. The exact presentation to ESXi depends on the adapter model, driver, firmware, and VMware support for that platform.

Hardware adapters also provide I/O offload. Offload means that the adapter performs some network or storage processing in adapter hardware instead of requiring the ESXi host CPU to perform most of that work in software. Offload behavior and supported features vary by adapter and driver.

Hardware CNAs are commonly selected for established enterprise SAN designs where the organization has validated adapter models, switch platforms, firmware combinations, and storage interoperability. Before deployment, verify all of the following:

ESXi release support for the CNA.
Supported adapter driver and firmware versions.
Switch, transceiver, and cabling compatibility.
FCoE and DCB support on the Ethernet fabric.
Interoperability with the Fibre Channel fabric or gateway.
Storage-array support, zoning requirements, and LUN presentation rules.

Software FCoE Adapters

A software FCoE adapter is an ESXi software component that performs FCoE processing while using a supported physical Ethernet NIC. Software FCoE support was introduced in the vSphere 5.x era.

Software FCoE does not eliminate the need for suitable physical hardware. The NIC must provide the capabilities required by the supported ESXi workflow, including applicable Data Center Bridging (DCB) support and relevant I/O offload capabilities. The host also needs the correct ESXi networking configuration and a supported association between the software FCoE adapter and the physical NIC.

A VMkernel adapter is an ESXi networking interface used for host services. It is relevant when configuring software-based storage networking paths, but creating a VMkernel adapter alone does not make an ordinary NIC FCoE-capable. The complete adapter, driver, ESXi release, switch configuration, and storage design must be supported together.

A typical software FCoE workflow is:

Confirm that the physical NIC is supported for software FCoE on the selected ESXi release.
Verify the required DCB and I/O offload capabilities.
Install or use the vendor-supported driver and firmware combination.
Configure the required ESXi networking components and physical NIC association.
Enable or create the software FCoE adapter through the supported ESXi or vSphere management interface.
Configure the Ethernet fabric for the required DCB and FCoE services.
Present the SAN LUN and rescan storage in ESXi.

Hardware FCoE Adapters vs Software FCoE Adapters

Characteristic	Hardware FCoE Adapter / CNA	Software FCoE Adapter
Where FCoE processing occurs	Primarily in adapter hardware and its firmware.	In ESXi software, with assistance from supported NIC features.
Physical hardware requirements	A supported CNA with Ethernet and FCoE capabilities.	A supported Ethernet NIC with the capabilities required for software FCoE.
NIC capability requirements	Capabilities are integrated into the CNA design and validated driver.	NIC support for DCB and applicable I/O offload is essential.
Use of adapter offload	Normally a central part of the adapter design.	Depends on the supported NIC and software implementation.
ESXi configuration dependency	ESXi must recognize the CNA and its supported storage interfaces.	ESXi networking and software FCoE configuration must be correct.
Compatibility validation considerations	Validate CNA, driver, firmware, switch, fabric, and array combinations.	Validate NIC, driver, firmware, ESXi, DCB, switch, fabric, and array combinations.
Typical design fit	Established enterprise SAN designs and validated converged hardware platforms.	Platforms where supported NIC capabilities and software FCoE workflows are available.

Neither option is universally better. Selection should follow the supported platform, SAN architecture, operational requirements, performance design, lifecycle practices, and hardware already deployed.

Required FCoE Infrastructure and Dependencies

FCoE requires consistent support from the ESXi host through the Ethernet fabric and into the Fibre Channel storage environment.

Component	Role in the FCoE Path	Key Validation Point
ESXi host	Runs virtual machines and exposes storage through a supported FCoE adapter.	Confirm ESXi release and storage adapter support.
CNA or supported NIC	Provides the physical Ethernet connection and hardware or software FCoE capability.	Check model, driver, firmware, DCB, and offload support.
FCoE adapter	Represents Fibre Channel storage connectivity to ESXi.	Verify that ESXi recognizes the adapter and its paths.
VMkernel networking where applicable	Provides required ESXi host networking components for supported software FCoE workflows.	Check association, VLAN or traffic configuration, and management workflow.
DCB-capable Ethernet switch	Carries converged traffic and provides the traffic controls required by FCoE.	Validate DCB, priority, bandwidth, and FCoE configuration end to end.
Fibre Channel fabric or gateway component where applicable	Connects the Ethernet FCoE side to the Fibre Channel SAN or supported storage environment.	Confirm fabric interoperability, zoning, and supported topology.
Storage array	Registers the host and presents logical storage devices.	Verify host identifiers, access controls, and LUN presentation.
LUN and VMFS datastore	The LUN is the presented device; VMFS can use it as an ESXi datastore.	Confirm device identity, ownership, formatting state, and paths.

Data Center Bridging

Data Center Bridging (DCB) is a group of Ethernet enhancements used to provide more controlled and reliable traffic behavior. FCoE deployments commonly require lossless Ethernet characteristics because Fibre Channel traffic is not designed to operate like ordinary best-effort Ethernet traffic.

DCB settings must be consistent across the relevant host adapters, switch interfaces, and connected infrastructure. Priorities, bandwidth allocation, and flow-control behavior should follow the validated vendor and SAN design. A standard Ethernet switch without the required DCB and FCoE support is not sufficient.

FCoE Initialization Protocol

FIP, or FCoE Initialization Protocol, is associated with FCoE discovery and initialization in supported environments. It helps establish the relationship between the host-side FCoE function and the FCoE fabric or forwarding infrastructure before normal FCoE communication begins.

If FIP discovery cannot complete, an adapter may appear partially configured while no usable Fibre Channel storage devices are discovered.

Storage Presentation After FCoE Connectivity

The storage array must present the intended LUNs to the ESXi host through the Fibre Channel/FCoE path. This usually involves registering the host initiators, configuring Fibre Channel zoning where applicable, adding the host to the correct storage group, and applying LUN masking or equivalent access controls.

After the SAN team presents a LUN, the ESXi administrator performs a storage rescan through the supported ESXi or vSphere management interface. The rescan allows ESXi to discover new devices and paths. The administrator should then verify:

The device identifier matches the intended LUN.
The expected number of paths is visible.
The device is not already used by another datastore or cluster design.
The LUN size and storage policy are appropriate.

A visible, supported unused LUN can be formatted as VMFS to create a datastore. If the LUN already contains a valid VMFS datastore, it may be mounted instead of reformatted. Never format a discovered device until its identity and intended use have been confirmed.

Multipathing means using multiple host-to-storage paths. Multiple adapters, switch connections, fabric paths, or array front-end ports can improve availability and may allow I/O distribution according to the supported path-selection policy. Redundant paths must be designed and validated rather than assumed from the presence of multiple cables.

Planning and Operational Cautions

Use the VMware Compatibility Guide and the adapter, switch, fabric, and storage vendor documentation before deployment.
Validate the complete combination of ESXi release, CNA or NIC, driver, firmware, switch, transceiver, Fibre Channel components, and storage array.
Keep DCB and FCoE settings consistent across the end-to-end path.
Isolate or logically separate storage traffic according to the approved network and SAN design.
Document host identifiers, switch interfaces, zoning, array host groups, LUN mappings, and expected paths.
Plan redundant adapters, switches, and storage paths when availability requirements justify them.
Manage adapter firmware and ESXi drivers as a tested pair; unplanned updates can break interoperability.
Consider the shared failure domain created by converged traffic and define how storage traffic is monitored and prioritized.

Practical Deployment Examples

Hardware CNA Deployment

An ESXi host has two supported CNAs connected to an FCoE-capable Ethernet switch. The switch is configured with the required DCB and FCoE services and connects to the Fibre Channel storage environment. The storage administrator registers the host, completes zoning and LUN masking, and presents a LUN. The ESXi administrator verifies that the hardware FCoE adapters and redundant paths appear, rescans storage, and creates or mounts the VMFS datastore.

Software FCoE Deployment

An ESXi host uses compatible Ethernet NICs with the required DCB and applicable offload capabilities. The administrator validates the NIC, driver, firmware, ESXi release, and switch support, then configures the required ESXi networking components and software FCoE adapter. After the SAN team presents a LUN, the administrator rescans storage and verifies the discovered device and paths.

Consolidating Host Connections

A validated converged design replaces separate Ethernet and Fibre Channel physical connections with supported converged Ethernet links. Cable and port counts are reduced while the host retains access to Fibre Channel storage. The design must still provide traffic isolation, appropriate DCB settings, and redundant paths.

Datastore Provisioning

After an FCoE LUN becomes visible in ESXi, the administrator confirms that it is the intended unused device. The administrator then creates a VMFS datastore or mounts an existing VMFS datastore, verifies the path state, and confirms that virtual machines can access the datastore.

FCoE Readiness Checklist

Area	Validation Questions
ESXi version support	Does the selected ESXi release support the adapter, NIC, and FCoE workflow?
Adapter and NIC compatibility	Is the exact CNA or NIC model supported, including the required capabilities?
Driver and firmware versions	Are the driver and firmware versions a vendor-supported combination?
DCB configuration	Are DCB policies, priorities, and bandwidth settings configured consistently?
FCoE/FIP support	Are FCoE services and FIP discovery enabled and permitted on the relevant infrastructure?
Switch interoperability	Are the Ethernet switch, transceivers, fabric components, and topology supported together?
Storage zoning and LUN presentation	Are host registration, zoning, masking, and LUN presentation complete?
Redundant paths and multipathing	Are multiple independent paths available and configured with an appropriate supported policy?

Troubleshooting FCoE in ESXi

No FCoE Adapter Appears in ESXi

Possible causes include an unsupported adapter or NIC, a missing or incorrect driver, incompatible firmware, or unmet software FCoE prerequisites.

Verify the exact platform and adapter against the VMware Compatibility Guide and vendor documentation.
Confirm that the physical adapter is detected by the host.
Check the supported driver and firmware combination.
For software FCoE, confirm that the selected NIC supports the required DCB and offload capabilities.

The Adapter Exists but No Storage Devices Are Discovered

Check whether FCoE or DCB is incorrectly configured on the Ethernet fabric, FIP discovery is unavailable, Fibre Channel zoning or array access is incomplete, or no LUN has been presented.

Validate the end-to-end switch and fabric configuration.
Confirm storage-array host registration, zoning, and LUN masking.
Perform a storage rescan after correcting access configuration.
Review adapter, switch, fabric, and storage event information.

Storage Paths Are Intermittent or Unavailable

Inconsistent DCB settings, physical link or transceiver problems, unsupported driver and firmware combinations, and failed redundant components can all cause path instability.

Check link status, transceivers, cabling, and hardware logs.
Compare DCB and FCoE settings across all relevant interfaces.
Validate firmware and driver levels.
Review multipathing status and isolate the failed path or component.

A Discovered LUN Cannot Be Used as the Expected Datastore

Verify that the LUN is presented correctly and that it is not already in use. Existing signatures, filesystems, cluster ownership, incorrect LUN identity, or unsuitable size and storage policies may explain the problem.

Confirm the LUN identity and ownership before formatting. Review existing datastore and device metadata, verify the intended shared-storage design, and avoid destructive operations until the device purpose is known.

Key Takeaways

FCoE transports Fibre Channel frames over Ethernet; it is distinct from iSCSI and NFS.
A hardware FCoE adapter, or CNA, performs much of the FCoE work in dedicated adapter hardware.
A software FCoE adapter performs FCoE processing in ESXi and still requires a supported physical NIC, DCB, and applicable offload capabilities.
FCoE requires more than ordinary Ethernet: the adapter, drivers, firmware, switches, DCB, FIP, Fibre Channel environment, and storage array must interoperate.
After connectivity is established, the array must present LUNs, ESXi must discover them, and the administrator can create or mount VMFS datastores.
Compatibility validation, traffic separation, redundant paths, and multipathing are central to a reliable deployment.

For a focused reference to this subject, see FCoE adapters explained.