PowerHA 7.1.`之CAA 进一步剖析

前 言：

      从上一篇，我们蜻蜓点水了CAA（CAA：cluster aware aix）这里，我们继续对CAA进行深入一点的 剖析，慢慢的揭开她神秘的面纱。 

       AIX 7.1 (and 6.1 TL6) introduced a new built-in clustering capability called Cluster Aware AIX (CAA). This feature enables system administrators to create clusters from a group
of AIX instances by using commands and programming APIs. It includes kernel-based heartbeating, monitoring, and an event infrastructure。

       CAA是AIX7.1 和 AIX6.1TL6引进的一个新的集群功能，他的功能是：系统管理员可以从一个AIX实例组通过命令和编程API来创建一个集群：包括内核心跳、监控和集群事件。

        

      CAA is primarily intended to provide a more reliable layer for clustering products such as PowerHA SystemMirror. Also, clients can directly use CAA layer functionalities to enhance their management tasks in their own computer
environments.

      CAA主要目的是给集群产品提供一个更加可靠的层，譬如powerha systemmirror这个集群产品。同时,客户端可以直接使用CAA层功能来增强他们的管理任务。(简化管理集群任务)

     CAA also introduces a new component, which is required for PowerHA cluster environments, called Cluster Repository Disk. It is a central repository for all cluster topology-related information, and it must be shared by all servers
that form the cluster.

     CAA同时也引进了一个PowerHA集群环境必须的新的组件：Cluster Repository Disk(集群存储库磁盘)——他是一个中心库，用来存储所有集群拓扑相关的信息，并且他必须被所有的集群节点所共享。

   In PowerHA 7.1.0, if the repository disk failed, the nodes shut down automatically. A new feature in PowerHA 7.1.1 called Repository Disk Resilience allows administrators to perform cluster maintenance tasks, for example, cluster
fallover and fallback, even after the repository disk experiences a failure. Now, CAA supports online repository disk replacement with no cluster effects. 

     在PowerHA7.1.0中，一旦这个库磁盘坏了，那么所有的集群节点都将自动关闭。在PowerHA7.1.1中新增了一个新特征：Repository Disk Resilience【存储库磁盘弹性】——他允许管理员执行集群维护任务，譬如，集群的接管和回切，甚至在存储库磁盘失败之后。现在，CAA支持在线的存储库磁盘替换，并且集群不会受到影响。关于Repository Disk Resilience，请继续查看接下来的主题——【Repository
Disk Resilience深入剖析】