iscsi可以将网络中一台机器上的磁盘共享给另一台机器
共享端叫iscsi服务器，连接端叫客户端。
实验的服务器环境为：
redhat6.0 32bit
ip：192.169.1.98
客户端环境：
redhat6.1 64bit
ip：192.169.1.100
服务器端构建
yum install scsi-target-utils #服务器需要安装的软件包
vim /etc/tgt/targets.conf #配置iscsi的配置文件
<target chen>
backing-store /dev/sdb7
initiator-address 192.169.1.100 #仅给192.169.1.100 做存储，不加这条表示可共所有主机使用。
backing-store /dev/sdb7
initiator-address 192.169.1.100 #仅给192.169.1.100 做存储，不加这条表示可共所有主机使用。
</target>
service tgtd start
chkconfig tgtd on
yum –y install iscsi-initiator-utils #客户端需要安装的软件包
iscsiadm –m discovery –t st–p 192.169.1.98#客户端发现操作
iscsiadm -m node -T chen -p 192.169.1.98 -l#客户端连接登陆
服务器端（ip：192.169.1.98）：
[chen@localhost 桌面]$ yum list|grep scsi
*Note* Red Hat Network repositories are not listed below. You must run this command as root to access RHN repositories.
iscsi-initiator-utils.i686 6.2.0.872-10.el6 @rhel-source
lsscsi.i686 0.23-2.el6 rhel-source
scsi-target-utils.i686 1.0.4-3.el6 rhel-source
[chen@localhost 桌面]$ su - root
密码：
[root@localhost ~]# yum install scsi-target-utils #安装服务器端软件
Loaded plugins: refresh-packagekit, rhnplugin
This system is not registered with RHN.
RHN support will be disabled.
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package scsi-target-utils.i686 0:1.0.4-3.el6 set to be updated
--> Processing Dependency: librdmacm.so.1 for package: scsi-target-utils-1.0.4-3.el6.i686
--> Processing Dependency: libibverbs.so.1 for package: scsi-target-utils-1.0.4-3.el6.i686
--> Processing Dependency: perl(Config::General) for package: scsi-target-utils-1.0.4-3.el6.i686
--> Running transaction check
---> Package libibverbs.i686 0:1.1.4-2.el6 set to be updated
--> Processing Dependency: libibverbs-driver for package: libibverbs-1.1.4-2.el6.i686
---> Package librdmacm.i686 0:1.0.10-2.el6 set to be updated
---> Package perl-Config-General.noarch 0:2.44-1.el6 set to be updated
--> Running transaction check
---> Package libmlx4.i686 0:1.0.1-7.el6 set to be updated
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
scsi-target-utils i686 1.0.4-3.el6 rhel-source 134 k
Installing for dependencies:
libibverbs i686 1.1.4-2.el6 rhel-source 43 k
libmlx4 i686 1.0.1-7.el6 rhel-source 27 k
librdmacm i686 1.0.10-2.el6 rhel-source 23 k
perl-Config-General noarch 2.44-1.el6 rhel-source 68 k
Transaction Summary
================================================================================
Install 5 Package(s)
Upgrade 0 Package(s)
Total download size: 295 k
Installed size: 672 k
Is this ok [y/N]: y
Downloading Packages:
--------------------------------------------------------------------------------
Total 830 kB/s | 295 kB 00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : perl-Config-General-2.44-1.el6.noarch 1/5
Installing : libmlx4-1.0.1-7.el6.i686 2/5
Installing : libibverbs-1.1.4-2.el6.i686 3/5
Installing : librdmacm-1.0.10-2.el6.i686 4/5
Installing : scsi-target-utils-1.0.4-3.el6.i686 5/5
Installed:
scsi-target-utils.i686 0:1.0.4-3.el6
Dependency Installed:
libibverbs.i686 0:1.1.4-2.el6 libmlx4.i686 0:1.0.1-7.el6
librdmacm.i686 0:1.0.10-2.el6 perl-Config-General.noarch 0:2.44-1.el6
Complete!
[root@localhost ~]# ls /dev/sda*
/dev/sda /dev/sda2 /dev/sda4 /dev/sda6
/dev/sda1 /dev/sda3 /dev/sda5 /dev/sda7
[root@localhost ~]# fdisk /dev/sda #注意服务器端要共享的盘必须是“原生”的，不能经过格式化，所以这里先分一个区
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
First cylinder (1614-2610, default 1614):
Using default value 1614
Last cylinder, +cylinders or +size{K,M,G} (1614-2610, default 2610): +500M#分一个500M的
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[root@localhost ~]# partx -a /dev/sda #刷新分区表
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5
BLKPG: Device or resource busy
error adding partition 6
BLKPG: Device or resource busy
error adding partition 7
[root@localhost ~]# ls /dev/sda*
/dev/sda /dev/sda2 /dev/sda4 /dev/sda6 /dev/sda8#可以看到有sda8了，就共享sda8
/dev/sda1 /dev/sda3 /dev/sda5 /dev/sda7
[root@localhost ~]# vim /etc/tgt/targets.conf
[root@localhost ~]# tail -5 /etc/tgt/targets.conf
#</target>
<target chen> 就加上这四行，这里这个分区的名字叫chen，redhat5中命名好像有一定格式，必须以iqn开头
backing-store /dev/sda8
initiator-address 192.169.1.100
</target>
[root@localhost ~]# /etc/init.d/tgtd start #启动服务，这样服务器端就配置完成了
正在启动 SCSI target daemon： [确定]
[root@localhost ~]#
客户端（ip：192.169.1.100）：
[chen@localhost 桌面]$ yum list|grep scsi
scsi-target-utils.x86_64 1.0.14-2.el6 @rhel-source
iscsi-initiator-utils.x86_64 6.2.0.872-21.el6 rhel-source
lsscsi.x86_64 0.23-2.el6 rhel-source
[chen@localhost 桌面]$ su - root
密码：
[root@localhost ~]# yum install -y iscsi-initiator-utils#先安装客服端
Loaded plugins: product-id, refresh-packagekit, subscription-manager
Updating Red Hat repositories.
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package iscsi-initiator-utils.x86_64 0:6.2.0.872-21.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
iscsi-initiator-utils x86_64 6.2.0.872-21.el6 rhel-source 579 k
Transaction Summary
================================================================================
Install 1 Package(s)
Total download size: 579 k
Installed size: 2.0 M
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : iscsi-initiator-utils-6.2.0.872-21.el6.x86_64 1/1
duration: 165(ms)
Installed products updated.
Installed:
iscsi-initiator-utils.x86_64 0:6.2.0.872-21.el6
Complete!
[root@localhost ~]# chkconfig --list|grep scsi #客户端服务自动开启了
iscsi 0:关闭1:关闭2:关闭3:启用4:启用5:启用6:关闭
iscsid 0:关闭1:关闭2:关闭3:启用4:启用5:启用6:关闭
[root@localhost ~]# iscsiadm -m discovery -t st -p 192.169.1.98 #发现服务器端是否有磁盘共享
正在启动 iscsid： [确定]
192.169.1.98:3260,1 chen #可以看到有一个名字叫chen的磁盘，说明发现了
[root@localhost ~]# iscsiadm -m node -T chen -p 192.169.1.98 -l#登陆服务器端
Logging in to [iface: default, target: chen, portal: 192.169.1.98,3260]
Login to [iface: default, target: chen, portal: 192.169.1.98,3260] successful.#登陆成功
[root@localhost ~]# fdisk -l #查看一下本地是否多一块磁盘
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000ee48e
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 1332 10485760 83 Linux
/dev/sda3 1332 1778 3584000 82 Linux swap / Solaris
/dev/sda4 1779 2610 6683040 5 Extended
/dev/sda5 1779 1831 425691 83 Linux
/dev/sda6 1832 1838 56196 83 Linux
/dev/sda7 1839 1970 1060258+ 83 Linux
Disk /dev/sdb: 534 MB, 534610944 bytes #可以看到这边多了一块磁盘sdb，大小约为500M
17 heads, 60 sectors/track, 1023 cylinders
Units = cylinders of 1020 * 512 = 522240 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/sdb doesn't contain a valid partition table
[root@localhost ~]# ls /dev/sdb
/dev/sdb
[root@localhost ~]# blkid /dev/sda1
/dev/sda1: UUID="18ed3ae9-6e4f-4674-ac6d-5d763ead42ce" TYPE="ext4"
[root@localhost ~]# blkid /dev/sdb #没有uuid信息，这块磁盘是“原生”的
[root@localhost ~]# ls /dev/sdb
/dev/sdb
[root@localhost ~]# fdisk /dev/sdb #可以像本地多了一块新的磁盘一样使用这块磁盘了，这里做一个分区
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x945cf8be.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1023, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1023, default 1023): +100M#分一个100M的主分区
Command (m for help): p
Disk /dev/sdb: 534 MB, 534610944 bytes
17 heads, 60 sectors/track, 1023 cylinders
Units = cylinders of 1020 * 512 = 522240 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x945cf8be
Device Boot Start End Blocks Id System
/dev/sdb1 1 202 102990 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# partx -a /dev/sdb
BLKPG: Device or resource busy
error adding partition 1
[root@localhost ~]# ls /dev/sdb*
/dev/sdb /dev/sdb1
[root@localhost ~]# mkdir /sdb1 #创建挂载点
[root@localhost ~]# mkfs.ext4 /dev/sdb1 #格式化sdb1
mke2fs 1.41.12 (17-May-2010)
文件系统标签=
操作系统:Linux
块大小=1024 (log=0)
分块大小=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
25792 inodes, 102988 blocks
5149 blocks (5.00%) reserved for the super user
第一个数据块=1
Maximum filesystem blocks=67371008
13 block groups
8192 blocks per group, 8192 fragments per group
1984 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
正在写入inode表: 完成
Creating journal (4096 blocks): 完成
Writing superblocks and filesystem accounting information: 完成
This filesystem will be automatically checked every 25 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mount /dev/sdb1 /sdb1/ #挂载
[root@localhost ~]# df -hT
文件系统 类型 容量 已用 可用 已用%% 挂载点
/dev/sda2 ext4 9.9G 3.3G 6.2G 35% /
tmpfs tmpfs 497M 420K 497M 1% /dev/shm
/dev/sda1 ext4 194M 27M 158M 15% /boot
/dev/sda6 ext4 54M 25M 26M 50% /quota
/dev/sr0 iso9660 3.4G 3.4G 0 100% /media/RHEL_6.1 x86_64 Disc 1
/dev/sr0 iso9660 3.4G 3.4G 0 100% /mnt/iso
/dev/sdb1 ext4 98M 5.6M 87M 6% /sdb1 #可以看到的确挂载上去了，文件系统类型为ext4
[root@localhost ~]#
注意：iscsi服务有时候服务重启会出现问题，若修改配置文件，先stop，然后start
/etc/init.d/tgtd stop
/etc/init.d/tgtd start
在客户端
iscsiadm --mode node -T chen -p 192.169.1.98:3260 -u 退出登录
iscsiadm --mode node -o delete -T chen -p 192.169.1.98:3260删除chen这个发现，要先退出，再删除，删除后必须重新发现，才能登录。