前言：

在  中实现了负载均衡器的高可用性，可是存在一个问题就是如果其中一台www服务器故障后，根据lvs的rr算法，当客户端有请求时还会访问到这台故障服务器。这时应用Ldirectord就可以解决这个问题。

那什么是Ldirectord, ldirectord is a daemon to monitor and administer real servers in a   cluster of load balanced virtual servers.  ldirectord typically used as a resource for   , but can also be run from the command line.  ldirectord has a configuration file which specifies the virtual services and their associated real servers. When  ldirectord is initialised it creates the virtual services for the clutster.  ldirectord monitors the health of the real servers by periodically requesting a known URL and checking that the response contains an expected response. If a real server fails then the server is removed and will be reactivated once it comes back on line. If all the real servers are down then a fall-back server is inserted into the pool, which will made quiescent one of the real web servers comes back on line. Typically, the fall-back server is localhost. If an HTTP virtual service is being provided then it is useful to run an Apache HTTP server that returns a page indicating that the service is temporarily inaccessible. (引用自“ ”），直观能看到那台服务器故障，用#sudo ipvsadm 看到的weight值为零（０）的那台就是。

实验环境：

与 中相同

１，配置主负载均衡器ubserver1:

    （１）安装Ldirectord软件包

    #sudo apt-get install ldirectord

#sudo cp /usr/share/doc/ldirectord/examples/ldirectord.cf  /etc/ha.d

    （２）ha.cf及authkeys配置文件内容不变与 中相同

（３）haresources文件做以下改动

ubserver1 192.168.3.100 lvs.sh 改为

ubserver1 192.168.3.100 lvs.sh ldirectord

   （４）ldirectord.cf文件配置：

#sudo vim /etc/ha.d/ldirectord.cf

当 checktype=negotiate时要求启用

request=”test.html” #在www服务器ubserver2，ubserver3的/var/www下建立test.html/页内容为“work”,这是因为： ldirectord monitors the health of the real servers by  periodically requesting a known  URL and  checking that the response contains an expected response

receive=”work”

当 checktype=connect时这两个配置可以注释掉因为 Connect only attemts to make a TCP/IP connection，我做实验时，把这两个注释掉，发现当一台www服务器down掉后，是发现不了的，不知道这是为什么。

*:ldirectord.cf的配置可以参考：