本帖最后由 Yong Huang 于 2016-1-29 11:52 编辑

12c ASM Flex architecture is something new to me. Based on what I read, a leaf node is only used to install software that will be managed by the cluster but it cannot be a database, because it can't have access to the shared disks. So this software can only be an application, in general sense. So it can be a web server, any third-party software.

> hub node 有3个， leaf node 有6个， 这个RAC 算是 9 个节点的RAC 吗 ？

I could be wrong on this. I think, whether the leaf nodes are counted into the cluster when you count the nodes may just be a matter of wording, or it's meaningful only when this is put in a specific context. In this example, you'll say it's a 3-node cluster when talking about the database, but 9-node when talking about all resources managed by the cluster.

> 怎么把应用服务器扯进来了

It makes sense to use certain software to manage the startup and shutdown order and dependency for other software. One such software program that offers this control is Oracle's GI (grid infrastructure), formerly called clusterware. Without using this program, your app server, such as JBoss or Apache, has to be controlled by yourself with a home-grown script as to when it should be brought up or down.

> 这里说的应用服务器是不是指 “ 只需要连接lead node ” 的应用服务器， 而不是指  leaf node   ?

I think it refers to the program running on the lead node. You can also say it *is* the lead node. I don't think " “ 只需要连接lead node ” 的应用服务器" is correct.