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为什么Rac的心跳线不支持交叉线?
作者：eygle |【转载时请务必以超链接形式标明文章原始出处和作者信息及本声明】链接：http://www.eygle.com/archives/2007/12/heartbeat_crossover_cables.html
在Oracle RAC的官方文档上有这样一句话：
Crossover cables are not supported for use with Oracle Clusterware interconnects.
也就是说Oracle不支持使用交叉线作为ClusterWare的interconnects。
这里的Not Support不是说交叉线不能用，而是说Oracle不建议这样做，同时不承担这样做而产生的一系列问题。
在Metalink上有这样一段描述说的非常清楚，摘录一下：
CROSS OVER CABLES ARE NOT SUPPORTED.
The requirement is to use a switch:Detailed Reasons:
1) cross-cabling limits the expansion of RAC to two nodes
2) cross-cabling is unstable:
a) Some NIC cards do not work properly with it. They are not able to negotiate the DTE/DCE clocking, and will thus not function.
These NICS were made cheaper by assuming that the switch was going to have the clock. Unfortunately there is no way to know which NICs do not have that clock.
b) Media sense behaviour on various OS's (most notably Windows) will bring a NIC down when a cable is disconnected.
Either of these issues can lead to cluster instability and lead to ORA-29740 errors (node evictions).Due to the benefits and stability provided by a switch, and their afforability ($200 for a simple 16 port GigE switch), and the expense and time related to dealing with issues when one does not exist, this is the only supported configuration.
实际上，交换机的引入是为了更高的扩展性和稳定性，这是合理的投入，在搭建RAC环境时值得投入。
-The End-
By eygle on 2007-12-13 10:00 | Comments (2) | Posted to Advanced | Edit |Pageviews:
留言 (2)
上个月给客户做rac的时候问过为啥不用双绞线，当时回答是oracle不建议这么做，看来是有官方支持的：）
Posted by: niubro at December 13, 2007 12:28 PM
非生产环境我用过。
Posted by: shahand at December 16, 2007 6:10 PM
