In vSphere 5.5 and later, you can persistently map a device (bus address) to a device name (alias). You can modify the mapping by using the Device Alias Configuration host profile. Using persistent mapping can help avoid compliance warnings for stateless hosts, and is also useful for stateful hosts.
The Device Alias Configuration host profile is selected by default, which means that aliases are assigned to each device. For example, if a host does not recognize one of the NICs during the boot process, the NIC aliases no longer change. That can help for management with scripts, and if you apply a host profile from a reference host.
To ensure uniform, persistent, and stable device naming across all hosts, use the device alias profile with homogeneous hosts only. These are hosts that are identically configured with the same network and storage cards in the PCI bus.
Device Alias Configuration Compliance Failures
For hosts are not fully homogenous, for example, the hosts contain different PCI cards or have different BIOS levels, if you apply the host profile from a reference host, a compliance check might result in a compliance failure. The compliance check ignores extra devices on the host that were not on the reference host. Select the host with the fewest devices as the reference host.
If the compliance check shows that he hosts are not fully homogeneous, the compliance failure cannot be remediated without modifying the hardware itself.
If the compliance check shows that the device aliases, for example, names such as vmhba3, are different from those on the reference host, remediation might be possible.
- To remediate a host that is not provisioned with vSphere Auto Deploy, perform host profile remediation and reboot the host.
- To remediate a host that is provisioned with vSphere Auto Deploy, reprovision a host.
Upgrading Systems for Device Alias Profiles
In ESXi versions earlier than 5.5, the Device Alias Configuration profile does not exist. Consider the following problems when you upgrade from previous versions of ESXi to ESXi 5.5 and later:
- For installed hosts, that is, hosts not provisioned with vSphere Auto Deploy, upgrading the ESXi host preserves aliases. After they are upgraded, aliases remain stable as long as the BIOS provides the information.
- When you upgrade a cluster of ESXi host provisioned with vSphere Auto Deploy image, the aliases do not change because ESXi 5.5 uses the same algorithm to generate aliases as earlier versions. Generate a new host profile for the reference host. This host profile includes the Device Alias Configuration profile. Set up vSphere Auto Deploy to apply the reference host's host profile to all other hosts for consistent device naming across your cluster.
- When upgrading a system, do not flash the BIOS, because this action can change aliases. Flashing the BIOS to the latest level is more appropriate for a new install.