本博文主要作为本人学习心得体会之用，欢迎探讨。平日查询资料有些不一定适应自己的环境，收集党吧。
系统版本如下：
LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: RedHatEnterpriseServer
Description: Red Hat Enterprise Linux Server release 6.6 (Santiago)
Release: 6.6
Codename: Santiago
参考链接：http://www.linuxidc.com/Linux/2013-06/85479.htm
http://blog.csdn.net/db_alleria/article/details/8219217
1、通过tgtd和iscsi做好服务端，客户端连接后，通过两条IP网络连接，完成iscsi登录注册。
2、通过fdisk -l看到多个设备，scsi_id -u -g /dev/sdd看到两个个1IET_相同。
3、
3、安装多路径程序yum install -y scsi*。
4、做好相关配置
cp /usr/share/doc/device-mapper-* /etc ：复制相关文件
cp /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf /etc ：复制配置文件模板
modprobe dm-multipath ：为内核加载模块
/etc/init.d/multipathd start ：启动服务
chkconfig multipathd on ：开机启动服务
5、查看配置结果
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multipath -ll ：查看多路径效果，以下为节选，/dev/mapper/mpathg 为多新建聚合后的设备连接文件，实际文件对应/dev/dm*内。
mpathe (1IET 00030002) dm-6 IET,VIRTUAL-DISK
size=2.0G features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=1 status=active
| `- 35:0:0:2 sdi 8:128 active ready running
`-+- policy='round-robin 0' prio=1 status=enabled
`- 36:0:0:2 sdl 8:176 active ready running
mpathd (1IET 00030001) dm-5 IET,VIRTUAL-DISK
size=2.0G features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=1 status=active
| `- 35:0:0:1 sdh 8:112 active ready running
`-+- policy='round-robin 0' prio=1 status=enabled
`- 36:0:0:1 sdk 8:160 active ready running
-----------------------------------------------------------------------------
fdisk -l|grep Disk ：查看硬盘结果
Disk /dev/sda: 21.5 GB, 21474836480 bytes
Disk identifier: 0x0009665b
Disk /dev/mapper/vg_ocm1-lv_root: 18.8 GB, 18832424960 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_ocm1-lv_swap: 2113 MB, 2113929216 bytes
Disk identifier: 0x00000000
Disk /dev/sdb: 32.2 GB, 32212254720 bytes
Disk identifier: 0x860a3e92
Disk /dev/sdc: 32.2 GB, 32212254720 bytes
Disk identifier: 0xd6e4c7d4
Disk /dev/sdd: 32.2 GB, 32212254720 bytes
Disk identifier: 0x166c030a
Disk /dev/sde: 32.2 GB, 32212254720 bytes
Disk identifier: 0x860a3e92
Disk /dev/sdg: 32.2 GB, 32212254720 bytes
Disk identifier: 0x166c030a
Disk /dev/sdh: 2147 MB, 2147483648 bytes
Disk identifier: 0xb8f15236
Disk /dev/sdf: 32.2 GB, 32212254720 bytes
Disk identifier: 0xd6e4c7d4
Disk /dev/sdk: 2147 MB, 2147483648 bytes
Disk identifier: 0xb8f15236
Disk /dev/sdi: 2147 MB, 2147483648 bytes
Disk identifier: 0xb9b8f8b3
Disk /dev/sdj: 2147 MB, 2147483648 bytes
Disk identifier: 0x3b8db307
Disk /dev/sdl: 2147 MB, 2147483648 bytes
Disk identifier: 0xb9b8f8b3
Disk /dev/sdn: 32.2 GB, 32212254720 bytes
Disk identifier: 0x35189686
Disk /dev/sdo: 32.2 GB, 32212254720 bytes
Disk identifier: 0x35189686
Disk /dev/sdm: 2147 MB, 2147483648 bytes
Disk identifier: 0x3b8db307
Disk /dev/mapper/mpatha: 32.2 GB, 32212254720 bytes
Disk identifier: 0x860a3e92
Disk /dev/mapper/mpathb: 32.2 GB, 32212254720 bytes
Disk identifier: 0xd6e4c7d4
Disk /dev/mapper/mpathc: 32.2 GB, 32212254720 bytes
Disk identifier: 0x166c030a
Disk /dev/mapper/mpathd: 2147 MB, 2147483648 bytes
Disk identifier: 0xb8f15236
Disk /dev/mapper/mpathe: 2147 MB, 2147483648 bytes
Disk identifier: 0xb9b8f8b3
Disk /dev/mapper/mpathf: 2147 MB, 2147483648 bytes
Disk identifier: 0x3b8db307
Disk /dev/mapper/mpathg: 32.2 GB, 32212254720 bytes
Disk identifier: 0x35189686
----------------------------------------------------------------------------
ls -al /dev/mapper/
drwxr-xr-x. 2 root root 240 May 23 11:26 .
drwxr-xr-x. 18 root root 4640 May 23 11:26 ..
crw-rw----. 1 root root 10, 58 May 23 11:17 control
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpatha -> ../dm-2
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpathb -> ../dm-3
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpathc -> ../dm-4
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpathd -> ../dm-5
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpathe -> ../dm-6
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpathf -> ../dm-7
lrwxrwxrwx. 1 root root 7 May 23 11:26 mpathg -> ../dm-8
lrwxrwxrwx. 1 root root 7 May 23 11:17 vg_ocm1-lv_root -> ../dm-0
lrwxrwxrwx. 1 root root 7 May 23 11:17 vg_ocm1-lv_swap -> ../dm-1
----------------------------------------------------------------------------------------------------------
ls -al /dev/dm*
brw-rw----. 1 root disk 253, 0 May 23 11:17 /dev/dm-0
brw-rw----. 1 root disk 253, 1 May 23 11:17 /dev/dm-1
brw-rw----. 1 root disk 253, 2 May 23 11:26 /dev/dm-2
brw-rw----. 1 root disk 253, 3 May 23 11:26 /dev/dm-3
brw-rw----. 1 root disk 253, 4 May 23 11:26 /dev/dm-4
brw-rw----. 1 root disk 253, 5 May 23 11:26 /dev/dm-5
brw-rw----. 1 root disk 253, 6 May 23 11:26 /dev/dm-6
brw-rw----. 1 root disk 253, 7 May 23 11:26 /dev/dm-7
brw-rw----. 1 root disk 253, 8 May 23 11:26 /dev/dm-8
