In vSAN clusters with configured fault domains, vSphere Lifecycle Manager remediates the hosts in an order that vSphere Lifecycle Manager calculates by factoring in the defined fault domains. For vSAN stretched clusters, vSphere Lifecycle Manager factors in the defined preferred and secondary site.
Fault Domains and vSAN Stretched Clusters
A fault domain consists of one or more vSAN hosts grouped according to their physical location in the data center. When configured, fault domains enable vSAN to tolerate failures of entire physical racks as well as failures of a single host, capacity device, network link, or a network switch dedicated to a fault domain.
You can configure fault domains for non-stretched and stretched vSAN clusters. A stretched cluster is a deployment model in which two or more hosts are part of the same logical cluster but are located in separate geographical locations. For more information about stretched clusters and configuring fault domains, see the Administering VMware vSAN documentation.
Upgrading vSAN Clusters Configured with Multiple Fault Domains
In earlier releases, vSphere Lifecycle Manager remediates the hosts in any cluster sequentially. To define which host to remediate, vSphere Lifecycle Manager only uses DRS recommendations. This behavior imposes some limitations. For example, if you want to upgrade all hosts from a configured fault domain first, you must check which hosts the fault domain includes and then manually select and remediate those hosts. Also, because vSphere Lifecycle Manager remediates the hosts sequentially, in case of failure, the cluster might be in a state where all fault domains are only partially upgraded.
Starting with vSphere 7.0 Update 1, vSphere Lifecycle Manager remediates vSAN clusters with configured fault domains by remediating all hosts in one fault domain at a time. To define the order of fault domains, vSphere Lifecycle Manager calculates and assigns priority to each fault domain for the vSAN cluster.
Remediation starts with the fault domain that has the highest priority. The priority of a fault domain is determined by the number of non-compliant hosts in that fault domain. The fewer non-compliant hosts in a fault domain, the higher the priority of that fault domain. However, if multiple fault domains have the same priority, vSphere Lifecycle Manager selects the first fault domain from the list of fault domains.
After vSphere Lifecycle Manager selects a fault domain, vSphere Lifecycle Manager uses DRS recommendations to select the optimal host within that domain to be remediated.
Upgrading vSAN Stretched Clusters
For stretched vSAN clusters, vSphere Lifecycle Manager first finishes upgrading all the hosts from the preferred site and then proceeds to upgrading the hosts from the secondary site.
If all the hosts in the preferred site are in a compliant state, then vSphere Lifecycle Manager skips the preferred site and starts remediating the hosts from the secondary site.
If any host in the entire cluster is in an incompatible state, remediation stops.
- vCenter Server version 7.0 Update 1.
- ESXi version 7.0 and later.