HP 3PAR StoreServ 7200 2-node HP 3PAR Policy Server Administrator's G - Page 49
Using Redundant Agent Gateways with Policy Server
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Using Redundant Agent Gateways with Policy Server To help you understand redundant gateways, let's start with non-redundant gateway operations. Normally, in a non-redundant gateway configuration, a given managed asset is associated with one Agent gateway. The Agent gateway sends asset data (data items, alarms, for example) to the HP 3PAR Enterprise Server on behalf of the managed asset, as well as receives and executes actions that are sent from the Enterprise Server to the managed asset. In a redundant gateway configuration, a managed asset may be associated with more than one Agent gateway. The Agent gateways with which a managed asset is associated are called redundant Agent gateways. Redundant Agent gateways are logically connected to the managed asset throughout the entire runtime. However, they do not communicate with each other, nor are they aware of each other's existence. In other words, a redundant Agent gateway has no indication that it is a part of a redundant gateway configuration. It is configured in exactly same manner as a regular, non-redundant Agent gateway. Although it recognizes the association of a managed asset with multiple Agent gateways, the HP 3PAR Enterprise Server treats the redundant Agent gateways equally. None of the Agent gateways that manage an asset is considered primary, so when an action is pending for the managed asset, it is delivered by the Agent gateway that contacts the Enterprise Server first. When another redundant Agent gateway contacts the Enterprise Server, even if it happens immediately after contact from the first Agent gateway, the pending action is not delivered. When a redundant gateway configuration is used, the managed asset must actively publish its data to an associated Agent gateway. Moreover, the managed asset is responsible for selecting the Agent gateway to which to publish the data. Otherwise, the data is going to be duplicated when it reaches the Enterprise Server. Communication with Policy Server in a Redundant Gateway Configuration In a non-redundant rateway configuration, HP 3PAR Policy Server delivers policies upon a contact from the asset. However, unlike messages regarding requested actions, which must be delivered only once, policies must be delivered to each Agent gateway that manages a given asset. Otherwise, the policies are not enforced properly. Therefore, Policy Server delivers the policy for a managed asset to all Agent gateways that are managing that asset. Important! If more than one Agent gateway is managing an asset, it is assumed that all managing Agent gateways are using the same Policy Server. If not, conflicting policies and unpredictable results are likely to occur. HP 3PAR Policy Server 5-5