The vSphere ROBO license model is perfect for organizations that have Remote Office Branch Office (ROBO) locations with a few hosts running workloads. Although being feature-rich, the ROBO clusters lacked the ability of automatic virtual machine migration when entering maintenance mode to perform upgrade or update operations.
With the announcement of the vSphere 6.7 Update 2 release, we introduce the new ROBO Enterprise (ROBO-ENT) license offering. It includes all the features of the ROBO Advanced license with the added features of VM encryption and DRS in Maintenance Mode (DRS-MM). This post will go into details about this new feature.
DRS-MM is a newly developed feature that relies some of the DRS internals of vSphere. It provides the ability for automatic virtual machine migrations when a host enters or exits maintenance mode. This is an essential feature for life-cycle management. It is automatically enabled when the ROBO Enterprise license is applied.
Important to notice is that DRS is disabled in ROBO Enterprise clusters, even when DRS-MM is activated through applying the vSphere ROBO Enterprise license. This is because DRS-MM will not balance workloads like in a typical cluster with vSphere DRS enabled. The sole purpose of DRS-MM is the ability to migrate virtual machines when hosts are put in maintenance mode. It is recommended not to have affinity rules in place because of the potential negative impact on DRS-MM operations. If affinity/anti-affinity rules are present in the system (due to migrating from a DRS supported license to ROBO enterprise license), the automatic virtual machine migration functionality may not work as expected.
When a ROBO Enterprise licensed host enters maintenance mode, DRS-MM will trigger the automatic virtual machine migration to other the other host(s) in the cluster. DRS-MM will create internal virtual machine affinity mappings. It uses vMotion operations to evacuate the virtual machine from the source host. That also means that vMotion requirements must be met for DRS-MM enabled clusters to be able to migrate virtual machine. Meaning a vMotion network must be in place and adequate resources must be available on the destination hosts to accompany the additional virtual machines during maintenance.
The internal virtual machine affinity mappings are not visible in the UI. When the source host exists maintenance mode, DRS-MM knows what virtual machines were running on it prior to maintenance mode and will try to migrate the virtual machines back to it.
More resources to learn
Please review the following links to learn more about vSphere ROBO and all features that are included.