1.start/stop multipathd process "service multipathd start/stop"
2.display the multipath topology "multipath -ll"
3.display the multipath debug info "multipath -v3"
4.Scan the HD "fdisk -l"
5.view the FC wwn " cat /sys/class/fc_host/host1/node_name"

1、 查看是否安装# rpm –qa | grep device
PackageKit-device-rebind-0.5.8-20.0.1.el6.x86_64
device-mapper-libs-1.02.74-10.el6.x86_64
device-mapper-event-1.02.74-10.el6.x86_64
device-mapper-1.02.74-10.el6.x86_64
device-mapper-event-libs-1.02.74-10.el6.x86_64
libimobiledevice-0.9.7-4.el6.x86_64

2、 配置文件只有一个：/etc/multipath.conf 。
配置前，请用fdisk -l 确认已可正确识别盘柜的所有LUN

redhat  多路径软件：device-mapper-multipath

多路径配置文件：/etc/multipath.conf
编辑注释掉以下几行：
blacklist {
             devnode "*"
}
 
修改后如下
#blacklist {
#   devnode "*"
#}
默认将所有设备加入黑名单。

3、.执行命令
modprobe dm-multipath  //加载多路径模块
lsmod |grep dm-multipath //查看是否加载多路径模块
/etc/init.d/multipathd restart // 重新启动多路径服务,监视路径，当路径损坏时进行路径切换。
chkconfig multipathd on //开机自启动
multipath -v2 或 multipath -ll  //输出多路径的设备的路径。如果没有出现路径，可以使用multipath -F 刷新
multipaht -F   使更新之后的配置生效

备注：kpartx command:为设备中的分区生成设备映射器设备。这个命令对于DM-MP分区DOS是很有用的。device-mapper-multipath需要它。
multipath -k 进入互动模式，对于故障排除很有帮助
4、  Check multipath command.                           
# multipath –ll
 
 
II. Disable multipath(卸载multipath)
1. Take a copy of /etc/multipath.conf
cp /etc/multipath.conf /etc/multipath.conf.bak

2. root user: Edit /etc/multipath.conf file and commentout all the entries in the file as root user

3. root user: Make sure the below entry in the multipath.conf file
blocklist {
devnode “*”
}

4. Take out the output of below command
sudo multipath -ll > /tmp/mpio_nodename.lst

5. disbale multipath process by using following command as root user.
# dmsetup ls   — displays all the device mapper
# /etc/init.d/multipathd stop
# /sbin/chkconfig multipathd off
# /sbin/dmsetup remove_all
# /sbin/rpm -e `rpm -qa | grep multipath`
6. Reboot the server