Domain Group Design
Domain group hierarchy design is one of your more important architectural design decisions. There is no right or wrong method. The goal is to best reflect your specific environment and management design requirements. You must understand the following attributes of domain groups:
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A domain group is an arbitrary grouping of individual Cisco UCS domains. The Cisco UCS Central administrator designs the grouping. A domain group is purely a Cisco UCS Central global construct. A domain is not aware that it is a member of a domain group.
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A Cisco UCS domain can only reside in one domain group at a time, unlike server pools, where one server can reside in multiple server pools.
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Cisco UCS Central places all domains in the ungrouped domain group at registration. Domains in the ungrouped domain group do not resolve to any global operational policies, even if the local Cisco UCS administrator has opted-in for global policy resolution control.
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Operational policies in effect for all domains in the domain group. They resolve and apply in a domain group.
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You can move Cisco UCS domains between domain groups. However, any domain group-to-domain move can be disruptive, depending on the policies in the destination domain group. Cisco UCS domain groups resolve their own policies from domain groups in which they reside. If a new domain joins a domain group, then it applies the new global operational policies, which may impact service.
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When considering global firmware management, evaluate the impact. Realize that more than one registered Cisco UCS domain might be subject to the policy definitions for that firmware. It might also be subject, simultaneously, to any changes or upgrades to that firmware policy.
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Newly registered domains can automatically join a domain group based on qualification policies at registration time. Domain-group policy qualifications work in a similar manner to server-pool policy qualifications.
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You can place global operational policies anywhere in the domain-group hierarchy, and override policies set at a higher level by setting a policy in a lower domain group.
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When an administrator moves a domain to a new domain group, the policies for the old domain group are not necessarily removed. Instead, the old policies remain in place, until the new policies overwrite the previous ones.
For example: Let's say that you have a UCS domain backup policy. The old policy defines the backup schedule and the new policy omits this policy. The UCS backups still occur based on the old schedule. They change if you create a new policy for the new domain group.
Policies which are resolved through references are removed if they are not present in the new domain group.
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Weigh the degree to which you employ the subdomains against the amount of administration and management required for managing the different subdomains.
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You can nest subdomain groups up to five levels deep, hierarchically, for finer granularity of policy control.