IBM z13s Technical Manual page 461

The following tasks show ensemble-related data on another HMC:
Scheduled operations: Displays ensemble-introduced scheduled operations, but you can
only view these scheduled operations.
User role: Shows ensemble tasks. You can modify and delete those roles.
Event monitoring: Displays ensemble-related events, but you cannot change or delete the
event.
HMC considerations when you use IBM zEnterprise Unified Resource
Manager to manage an ensemble
The following considerations are valid when you use Unified Resource Manager to manage
an ensemble:
All HMCs at the supported code level are eligible to create an ensemble. Only HMCs with
FC 0094, FC 0092, or FC 0091 at Driver 27 or later can be primary or alternate HMCs for
z13s servers.
The primary HMC and the alternate HMC must be the same machine type and feature
code.
A single HMC pair manages the ensemble that consists of a primary HMC and an
alternate HMC.
Only one primary HMC manages an ensemble, which can consist of a maximum of eight
CPCs and up to eight zBX Model 004 systems.
The HMC that ran the Create Ensemble wizard becomes the primary HMC. An alternate
HMC is elected and paired with the primary.
The Primary HMC (Version 2.13.1 or later) and Alternate HMC (Version 2.13.1 or later) are
displayed on the HMC banner. When the ensemble is deleted, the titles change back to
the default.
A primary HMC is the only HMC that can run ensemble-related management tasks. These
tasks include create virtual server, manage virtual networks, and create workload.
A zEnterprise ensemble can have a maximum of 16 nodes (eight CPCs plus eight zBX
Model 004 systems), and is managed by one primary HMC and its alternate. Each node
comprises a zEnterprise CPC or a zBX Model 004.
Any HMC can manage up to 100 CPCs. The primary HMC can run all non-ensemble HMC
functions on CPCs that are not members of the ensemble.
The primary and alternate HMCs must be on the same LAN segment.
The alternate HMC's role is to mirror the ensemble configuration and policy information
from the primary HMC.
When failover happens, the alternate HMC becomes the primary HMC. This behavior is
the same as primary and alternate SEs.
Chapter 11. Hardware Management Console and Support Elements
433