7.0

Device Alias Configuration
Device aliases, also called device names, are short names associated with I/O adapters in an I/O
subsystem. For example, network uplinks have aliases such as vmnic0, vmnic1, and so on. SCSI
adapter objects in the storage subsystem and graphics device objects also have aliases.
A hardware device can be presented as multiple I/O adapters in the I/O subsystem. The I/O
adapters can be of a different type from the underlying physical device. For example, an FCoE
device is a storage I/O adapter that uses NIC hardware. Software iSCSI is a storage adapter using
the network stack at the IP layer. Therefore, in the ESXi native driver model, aliases formally refer
only to I/O adapters, and not to physical devices such as a PCI NIC or a PCI HBA.
Device Alias Assignment
A stateless ESXi deployment model is one where the ESXi host is not installed on hard disks,
and is typically booted by using PXE. A stateful ESXi deployment model is one where the ESXi
host is installed on local hard disks. Device alias assignment occurs during a stateless ESXi boot
or a fresh installation of stateful ESXi. The ESXi host assigns aliases to I/O adapters in an order
which is based on the underlying hardware enumeration order. The ESXi host assigns aliases first
to on-board devices and then to add-in cards based on slot order. The ESXi host cannot assign
aliases to absent devices or devices without supported drivers.
Аn uplink that uses a NIC that is built into the motherboard receives a vmnicN alias with lower
number compared to an uplink of a PCI add-in card. The NIC driver might register more than one
uplink. If one of the uplinks does not correspond to an enumerable hardware device, the ESXi host
assigns the next available alias to the uplink after the uplink is registered with the system.
Persistence of Device Alias Configuration
After the ESXi host assigns aliases, alias configuration is persisted. The ESXi host attempts to keep
the alias of each device the same regardless of the ESXi version updates, or hardware changes,
such as adding or removing devices from slots.
The persistence of the alias configuration depends on the deployment model.
n In stateful systems, the alias configuration is persisted locally on the host.
n In stateless systems, if you do not manage the stateless system by using host profiles, the alias
configuration is not persisted locally on the host.
n In stateful and stateless systems that you manage by using host profiles, the alias configuration
is persisted in the host profile. If you apply a host profile to a stateful host, the host profile
overrides any locally persisted alias configuration.
Changes in the Device Alias Configuration
The persistence of alias configuration is based on the bus addresses of devices. If the bus address
of a device is altered, the persisted alias configuration becomes inapplicable and the aliases
assigned to the device might change.
Changes in the device alias configuration might occur in the following cases:
n A driver upgrade might enumerate or present an I/O adapter differently to the system
compared to how the I/O adapter is presented before the driver upgrade.
VMware ESXi Installation and Setup
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