Use vSphere Update Manager to upgrade the firmware of the servers that run your vSAN clusters.
In a vSAN cluster, the SCSI controller firmware and the physical drive firmware are handling the most of the data communication. To ensure your vSAN cluster health, starting with vSphere 6.7 Update 1 you can use Update Manager to run periodical checks of the underlying firmware versions of your servers, and initiate an upgrade when necessary.
Because firmware upgrades affect the hardware layer in your vSphere environment, they usually are rare events. Firmware upgrades occur during initial ESXi host setup or during major updates of vSphere or vSAN.
To upgrade the firmware on a host in the vSAN cluster, first download the vendor firmware tool. The vendor tool is a required by the vSAN firmware engine to detect, download and install the supported and recommended firmware for the ESXi servers in the vSAN cluster. If your vCenter Server system is connected to the Internet, you can download the vendor firmware tool directly from its default depot location. Otherwise, you can upload the tool from a custom location.
To determine whether the vendor firmware tool is downloaded for the hosts in your vSAN cluster, go to Host Updates under the Updates tab in the vSphere Client. If a host in the cluster is missing the vendor firmware tool, you see a warning message.
Тhe tool scans the firmware versions of the hardware components of the host. If any of the hosts in the vSAN cluster run an earlier version than the latest supported available firmware, the firmware engine generates a cluster baseline group, containing firmware updates and adds it to the vSAN cluster baseline group.
A vSAN cluster baseline group can include a single firmware baseline for each host in the cluster.
The ESXi hosts in the vSAN cluster are updated one at a time. Beside the firmware baseline, the vSAN baseline group can include software update items, such as ISO images, drivers, and patches packed in a software upgrade baseline. The current state of the software installed on the vSAN cluster is checked against the Hardware Compatibility List (HCL) from the VMware Compatibility Guide. If software upgrade recommendations are determined, the vSAN recommendation engine creates a vSAN software baseline and packs is with the firmware upgrade baseline in a baseline group that Update Manager can use to upgrade the hosts in the vSAN cluster.
You can perform firmware upgrade operations separately from the software upgrade operations that the cluster baseline group recommends. You can also decide to upgrade the firmware of a single host in the vSAN cluster or the entire cluster.
For more information about build recommendations in the vSAN cluster, see Administering VMware vSAN documentation.
To see a list with all I/O controllers whose firmware you can update with Update Manager, see https://kb.vmware.com/s/article/60382.