You have the option of converting clusters to use a new host type, if the original host type you selected no longer meets your needs.

Currently, the following conversions are available:
  • You can convert clusters containing i3 hosts to i3en or i4i hosts.
  • You can convert clusters containing i3en hosts to i4i hosts.
Important: Compute policy tags are not copied over during cluster conversion. You will need to attach host policy tags after conversion is complete. See "Impact of Compute Policies on Cluster Conversion" in Using Policies and Profiles.

It is not possible to roll back a cluster conversion. You can't convert i4i hosts to i3en or i3 hosts, nor can you convert i3en hosts to i3 hosts.

Contact your VMware representative to schedule a cluster conversion. A conversion window is scheduled and you will have the opportunity to approve the conversion window.

You receive notifications when a cluster conversion is scheduled, about to start, and completed. To ensure that you receive these notifications, ensure that is added to your email allow list.

Conversion to i4i Hosts

Cluster conversion to i4i hosts is possible on any of these SDDC versions:
  • SDDC version 1.22 or later.
  • SDDC version 1.20v2 or later.
  • SDDC version 1.18v8 or later.

After conversion to i4i hosts, the cluster might contain more hosts than were present in the original cluster. This is a precaution to ensure complete conversion. After cluster conversion is complete, check the cluster and remove any hosts that are not needed. VMware recommends that you remove the hosts within 24 hours after cluster conversion is complete.

Cluster Conversion Process

Three days before the cluster conversion is scheduled, VMware runs pre-checks on the cluster to ensure that it is ready for conversion.

During the conversion, EDRS scale-in is turned off so that it does not interfere with the process. Two hosts of the target host type are added to the cluster. The NSX Edge VMs are migrated to these two new hosts. Then workload VMs are migrated off of one of the original hosts and it is removed from the cluster. The removal of original hosts and the addition of target hosts is repeated until all original hosts have been removed and the cluster is fully converted. Then EDRS scale-in is re-enabled. Based on cluster utilization, the number of final target hosts might differ from the number of hosts you started with.

The estimated final number of hosts in the target cluster is based on the following factors:
  • The current used capacity in the starting vSAN cluster.
  • The number of hosts in the starting cluster.
  • The space-savings efficiency ratio of the starting cluster.
  • The available capacity in the capacity tier of storage for the target host instances.
  • An extra 20% headroom for vSAN operations and overhead.
  • The number of hosts required to satisfy the configured vSAN Policies applied to VMs in the cluster. The conversion logic tries to prevent the number of hosts in the target cluster from exceeding the minimum required to satisfy all VM storage policies in use, while taking into consideration factors such as storage requirements, vSAN overhead, and the need to balance host counts in multi-AZ SDDCs.

The estimate is a best guess only. The final result might differ based on the state of the cluster. After conversion, EDRS might scale in or scale out the cluster based on the resource usage and the EDRS policy applied to the cluster. You can also manually resize the cluster after conversion is complete.

Cluster conversion might take hours to days to complete. VMware recommends taking a backup before the cluster conversion takes place.

Impact of Cluster Conversion on Operation

There is no downtime to workload VMs or management appliances during the conversion process. You are unable to perform the following operations during cluster conversion:
  • Removing hosts
  • Editing EDRS policy settings
During cluster conversion, do not perform the following actions on the cluster which is being converted:
  • Do not perform hot or cold workload migrations to or from the cluster being converted.
  • Do not perform workload provisioning (New/Clone VM).
  • Do not make changes to Storage-based Policy Management settings for workload VMs.
  • Avoid starting HCX migrations that might overlap with the conversion window.
  • Avoid the following DRaaS activity on the cluster being converted:
    • Create or destroy site pairings
    • Execute recovery plan
    • Planned migration
    • Test failover or test cleanup
    • Real failover
    • Reprotect
    • Replication management operations, such as configuring or stopping replication
  • Do not add or remove hosts from the cluster being converted.

Cluster Conversion and Billing

During the cluster conversion process, your cluster contains a mixture of host types. However, your billing does not change during the conversion process. All new hosts added at this point are non-billable. After the conversion is complete, the hosts are billable for the new host type at the new host type price.

Converting the cluster host types does not convert any term commitments that you have purchased. For example, if you purchased an i3 term commitment, and later converted that cluster to use i3en hosts, you can choose to purchase a new i3en term commitment or have your i3en hosts billed at the on-demand rate. In either case, you will continue to pay for your i3 term commitment.