5.10.1 Understanding Oracle Flex Clusters

5.10.1了解Oracle Flex集群

Starting with Oracle Grid Infrastructure 12c Release 2 (12.2), Oracle Grid Infrastructure cluster configurations are Oracle Flex Clusters deployments.

从Oracle网格基础设施的12C版本2（12.2），Oracle网格基础设施的集群配置Oracle集群部署Flex。

Oracle Grid Infrastructure installed in an Oracle Flex Cluster configuration is a scalable, dynamic, robust network of nodes. Oracle Flex Clusters provide a platform for Oracle Real Application Clusters databases with large numbers of nodes, to support massive parallel query operations. Oracle Flex Clusters also provide a platform for other service deployments that require coordination and automation for high availability.

Oracle网格基础设施安装在Oracle flex集群配置中是一个可伸缩的、动态的、健壮的节点网络。Oracle Flex集群为Oracle实际应用程序集群提供了大量节点的数据库平台，支持大规模并行查询操作。Oracle Flex集群还为需要高可用性的协调和自动化的其他服务部署提供了一个平台。

All nodes in an Oracle Flex Cluster belong to a single Oracle Grid Infrastructure cluster. This architecture centralizes policy decisions for deployment of resources based on application needs, to account for various service levels, loads, failure responses, and recovery.

Oracle Flex集群中的所有节点都属于单一的Oracle网格基础设施集群。这种架构集中决策基于应用需求的资源配置，考虑到不同的服务水平、负荷、故障响应和恢复。

Oracle Flex Clusters contain two types of nodes arranged in a hub and spoke architecture: Hub Nodes and Leaf Nodes. The number of Hub Nodes in an Oracle Flex Cluster can be as many as 64. The number of Leaf Nodes can be many more. Hub Nodes and Leaf Nodes can host different types of applications and perform parallel query operations.

Oracle Flex集群包含两种类型的节点，它们位于一个轮辐式体系结构中：集线器节点和叶节点。Oracle Flex集群中的集线器节点数量可以多达64个。叶节点的数目可以更多。集线器节点和叶节点可以承载不同类型的应用程序，并执行并行查询操作。

Hub Nodes in Oracle Flex Clusters are tightly connected, and have direct access to shared storage. In an Oracle Flex Cluster configuration, Hub Nodes can also provide storage service for one or more Leaf Nodes. Three Hub Nodes act as I/O Servers for storage access requests from Leaf Nodes. If a Hub Node acting as an I/O Server becomes unavailable, then Oracle Grid Infrastructure starts another I/O Server on another Hub Node.

Oracle Flex集群中的集线器节点紧密相连，可以直接访问共享存储。在Oracle flex集群配置中，集线器节点还可以为一个或多个叶节点提供存储服务。三个集线器节点充当来自叶节点的存储访问请求的I/O服务器。如果作为I/O服务器的集线器节点不可用，则Oracle网格基础设施将在另一个集线器节点上启动另一个I/O服务器。

Leaf Nodes in Oracle Flex Clusters do not require direct access to shared storage, but instead request data through Hub Nodes. Hub Nodes can run in an Oracle Flex Cluster configuration without having any Leaf Nodes as cluster member nodes, but Leaf Nodes must be members of a cluster with a pool of Hub Nodes.

oracle集群中的叶节点不需要直接访问共享存储，而是通过集线器节点请求数据。集线器节点可以在Oracle flex集群配置中运行，而不需要任何叶节点作为集群成员节点，但是叶节点必须是具有一个集线器节点池的集群成员。

Oracle RAC database instances running on Leaf Nodes are referred to as far Oracle ASM client instances. Oracle ASM metadata is never sent to the far client database instance. Instead, the far Oracle ASM client database sends the I/O requests to I/O Server instances running on Hub Nodes over the Oracle Flex ASM network.

运行在叶节点上的Oracle RAC数据库实例称为远Oracle ASM客户机实例。Oracle ASM元数据从不发送到远客户机数据库实例。相反，远Oracle ASM客户机数据库将I/O请求发送到在Flex ASM网络上运行在集线器节点上的I/O服务器实例。

You configure servers for Hub Node and Leaf Node roles. You can designate servers for manual or automatic configuration.

您为集线节点和叶节点角色配置服务器。您可以为手动或自动配置指定服务器。

If you select manual configuration, then you must designate each node in your cluster as a Hub Node or a Leaf Node. Each role requires different access to storage. To be eligible for the Hub Node role, a server must have direct access to storage. To be eligible for the Leaf Node role, a server may have access to direct storage, but it does not require direct access, because leaf nodes access storage as clients through Hub Nodes.

如果选择手动配置，则必须将集群中的每个节点指定为集线器节点或叶节点。每个角色需要不同的存储访问权限。为了获得集线器节点角色的资格，服务器必须具有对存储的直接访问权。为了获得叶节点角色的资格，服务器可以访问直接存储，但不需要直接访问，因为叶节点通过集线器节点访问作为客户机的存储。

If you select automatic configuration of roles, then cluster nodes that have access to storage and join are configured as Hub Nodes, up to the number that you designate as your target. Other nodes that do not have access to storage or that join the cluster after that target number is reached join the cluster as Leaf Nodes. Nodes are configured as needed to provide Hub Nodes configured with Local or Near ASM to provide storage client services, and Leaf Nodes that are configured with direct access to Oracle ASM disks can be reconfigured as needed to become Hub Nodes. Oracle recommends that you select automatic configuration of Hub and Leaf node roles.

如果选择角色的自动配置，那么可以访问存储和连接的集群节点被配置为集线器节点，直到您指定为目标的数量为止。其他无法访问存储或在目标号到达后加入集群的节点将集群作为叶节点连接。节点根据需要配置，以提供由本地或近ASM配置的集线器节点来提供存储客户服务，并且配置为直接访问Oracle ASM磁盘的叶节点可以根据需要重新配置成集线器节点。Oracle建议您选择集线器和叶节点角色的自动配置。