ISCSI技术介绍：
iSCSI技术实现了物理硬盘设备与TCP/TP网络传输协议的相互结合，使得用户可以通过互联网方便的获取到远程机房提供的共享存储资源
1.ISCSI网络磁盘共享：
【在服务端server】:新建磁盘，划分分区
[root@server ~]# yum install targetcli -y ##安装targetcli服务
Loaded plugins: langpacks
rhel_dvd | 4.1 kB 00:00
Resolving Dependencies
[root@server ~]# fdisk /dev/vdb ##新建磁盘
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xe43428f2.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-20971519, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +2G ##建立一个2G的磁盘
Partition 1 of type Linux and of size 2 GiB is set
Command (m for help): wq
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@server ~]# partprobe ##手动更新分区表
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
[root@server ~]# systemctl start target ##开启target服务
[root@server ~]# systemctl enable target ##开机自动开启
ln -s '/usr/lib/systemd/system/target.service' '/etc/systemd/system/multi-user.target.wants/target.service'
[root@server ~]# targetcli ##进入iscsi目标交互式配置模式
Warning: Could not load preferences file /root/.targetcli/prefs.bin.
targetcli shell version 2.1.fb34
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help'.
/> /backstores/block create westos:storage1 /dev/vdb1 ##和逻辑卷建立联系，且给要共享的逻辑卷起名，提供硬盘创建储存设备
Created block storage object westos:storage1 using /dev/vdb1.
/> /iscsi create iqn.2018-06.com.example:storage1 ##创建iqn名称（每个发起端和目标需要以名称进行标识） iqn域名反写：随机串
Created target iqn.2018-06.com.example:storage1.
Created TPG 1.
/> ls ##查看iscsi1对象
o- / ..................................................................... [...]
o- backstores .......................................................... [...]
| o- block .............................................. [Storage Objects: 1]
| | o- westos:storage1 ........... [/dev/vdb1 (2.0GiB) write-thru deactivated]
| o- fileio ............................................. [Storage Objects: 0]
| o- pscsi .............................................. [Storage Objects: 0]
| o- ramdisk ............................................ [Storage Objects: 0]
o- iscsi ........................................................ [Targets: 1]
| o- iqn.2018-06.com.example:storage1 .............................. [TPGs: 1]
| o- tpg1 ........................................... [no-gen-acls, no-auth]
| o- acls ...................................................... [ACLs: 0]
| o- luns ...................................................... [LUNs: 0]
| o- portals ................................................ [Portals: 0]
o- loopback ..................................................... [Targets: 0]
/> /iscsi/iqn.2018-06.com.example:storage1/tpg1/acls create iqn.2018-06.com.example:westoskey ##创建客户端连接服务端密钥
Created Node ACL for iqn.2018-06.com.example:westoskey
/> /iscsi/iqn.2018-06.com.example:storage1/tpg1/luns create /backstores/block/westos:storage1 ##关联设备
Created LUN 0.
Created LUN 0->0 mapping in node ACL iqn.2018-06.com.example:westoskey
/> /iscsi/iqn.2018-06.com.example:storage1/tpg1/portals create 172.25.254.220 ##启动监听程序
Using default IP port 3260
Created network portal 172.25.254.220:3260.
/> exit ##退出
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json【在客户端desktop】：安装服务，进行测试
[root@client ~]# yum install iscsi-initiator-utils.x86_64 -y ##安装服务包
[root@client ~]# vim /etc/iscsi/initiatorname.iscsi ##编辑key配置文件
编辑：InitiatorName=iqn.2018-06.com.example:westoskey
[root@client ~]# systemctl restart iscsi
[root@client ~]# systemctl restart iscsid.service ##开启服务
[root@client ~]# iscsiadm -m discovery -t st -p 172.25.254.220 ##发现服务（-m 指定服务器，-t 发现网络设备类型，-p 主机IP）
172.25.254.220:3260,1 iqn.2018-06.com.example:storage1
[root@client ~]# iscsiadm -m node -T iqn.2018-06.com.example:storage1 -p 172.25.254.220 -l ##登录服务（-T 指定域名 -l 指定lun的ID号 ）
Logging in to [iface: default, target: iqn.2018-06.com.example:storage1, portal: 172.25.254.220,3260] (multiple)
Login to [iface: default, target: iqn.2018-06.com.example:storage1, portal: 172.25.254.220,3260] successful.
[root@client ~]# fdisk -l ##查看磁盘
Disk /dev/sda: 2147 MB, 2147483648 bytes, 4194304 sectors ##有刚才共享的2G磁盘
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 4194304 bytes
2.共享磁盘的使用与自动挂载：
【在客户端desktop】：
[root@client ~]# fdisk /dev/sda ##新建磁盘
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x829ead8c.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (8192-4194303, default 8192):
Using default value 8192
Last sector, +sectors or +size{K,M,G} (8192-4194303, default 4194303): +1000M
Partition 1 of type Linux and of size 1000 MiB is set
Command (m for help): wq
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@client ~]# mkfs.xfs /dev/sda1 ##格式化新建磁盘
meta-data=/dev/sda1 isize=256 agcount=8, agsize=32000 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=256000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@client ~]# vim /etc/fstab ##编辑配置文件
写入：/dev/sda1 /mnt xfs defaults,_netdev 0 0
[root@client ~]# mount /dev/sda1 /mnt ##手动挂载
[root@client ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda1 10473900 3192672 7281228 31% /
devtmpfs 469344 0 469344 0% /dev
tmpfs 484932 124 484808 1% /dev/shm
tmpfs 484932 12808 472124 3% /run
tmpfs 484932 0 484932 0% /sys/fs/cgroup
/dev/mapper/vg0-vo 483670 2356 451823 1% /home
/dev/sda1 1020588 33056 987532 4% /mnt ##挂载成功
[root@client ~]# umount /mnt
[root@client ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda1 10473900 3192672 7281228 31% /
devtmpfs 469344 0 469344 0% /dev
tmpfs 484932 124 484808 1% /dev/shm
tmpfs 484932 12808 472124 3% /run
tmpfs 484932 0 484932 0% /sys/fs/cgroup
/dev/mapper/vg0-vo 483670 2356 451823 1% /home
[root@client ~]# reboot ##重启虚拟机
Connection to 172.25.254.120 closed by remote host.
Connection to 172.25.254.120 closed.
[kiosk@foundation20 Desktop]$ ssh root@172.25.254.120
root@172.25.254.120's password:
Last login: Sun Jun 3 01:47:08 2018
[root@client ~]# df ##查看挂载
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda1 10473900 3191960 7281940 31% /
devtmpfs 469344 0 469344 0% /dev
tmpfs 484932 84 484848 1% /dev/shm
tmpfs 484932 12792 472140 3% /run
tmpfs 484932 0 484932 0% /sys/fs/cgroup
/dev/mapper/vg0-vo 483670 2356 451823 1% /home
/dev/sda1 1020588 33056 987532 4% /mnt ##自动挂载成功
3.删除共享磁盘：
【在客户端desktop】：
[root@client ~]# yum install tree -y ##安装数结构显示服务
Loaded plugins: langpacks
Resolving Dependencies
--> Running transaction check
---> Package tree.x86_64 0:1.6.0-10.el7 will be installed
--> Finished Dependency Resolution
[root@client ~]# tree /var/lib/iscsi/ ##数结构显示iscsi主文件
/var/lib/iscsi/
|-- ifaces
|-- isns
|-- nodes
| `-- iqn.2018-06.com.example:storage1
| `-- 172.25.254.220,3260,1
| `-- default
|-- send_targets
| `-- 172.25.254.220,3260
| |-- iqn.2018-06.com.example:storage1,172.25.254.220,3260,1,default -> /var/lib/iscsi/nodes/iqn.2018-06.com.example:storage1/172.25.254.220,3260,1
| `-- st_config
|-- slp
`-- static
10 directories, 2 files
[root@client ~]# fdisk -l ##查看共享磁盘
Device Boot Start End Blocks Id System
/dev/sda1 8192 2056191 1024000 83 Linux
[root@client ~]# df ##查看挂载
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda1 10473900 3193200 7280700 31% /
devtmpfs 469344 0 469344 0% /dev
tmpfs 484932 84 484848 1% /dev/shm
tmpfs 484932 12792 472140 3% /run
tmpfs 484932 0 484932 0% /sys/fs/cgroup
/dev/mapper/vg0-vo 483670 2356 451823 1% /home
/dev/sda1 1020588 33056 987532 4% /mnt
[root@client ~]# umount /mnt ##先进行卸载
[root@client ~]# df ##查看
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda1 10473900 3193200 7280700 31% /
devtmpfs 469344 0 469344 0% /dev
tmpfs 484932 84 484848 1% /dev/shm
tmpfs 484932 12788 472144 3% /run
tmpfs 484932 0 484932 0% /sys/fs/cgroup
/dev/mapper/vg0-vo 483670 2356 451823 1% /home ##卸载成功
[root@client ~]# vim /etc/fstab ##还原配置文件
[root@client ~]# fdisk -l ##查看共享磁盘
Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x00013f3e
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 20970332 10484142+ 83 Linux
Disk /dev/vdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x09ee18d7
Device Boot Start End Blocks Id System
/dev/vdb1 2048 1026047 512000 8e Linux LVM
Disk /dev/mapper/vg0-vo: 520 MB, 520093696 bytes, 1015808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sda: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 4194304 bytes
Disk label type: dos
Disk identifier: 0x829ead8c
Device Boot Start End Blocks Id System
/dev/sda1 8192 2056191 1024000 83 Linux
[root@client ~]# iscsiadm -m node -T iqn.2018-06.com.example:storage1 -p 172.25.254.220 -u ##登出iscsi服务，暂时断开连接
Logging out of session [sid: 1, target: iqn.2018-06.com.example:storage1, portal: 172.25.254.220,3260]
Logout of [sid: 1, target: iqn.2018-06.com.example:storage1, portal: 172.25.254.220,3260] successful.
[root@client ~]# fdisk -l ##共享磁盘消失
Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x00013f3e
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 20970332 10484142+ 83 Linux
Disk /dev/vdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x09ee18d7
Device Boot Start End Blocks Id System
/dev/vdb1 2048 1026047 512000 8e Linux LVM
Disk /dev/mapper/vg0-vo: 520 MB, 520093696 bytes, 1015808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
[root@client ~]# iscsiadm -m node -T iqn.2018-06.com.example:storage1 -p 172.25.254.220 -o delete ##删除iscsi目标的本地记录，以永久断开连接
[root@client ~]# tree /var/lib/iscsi/ ##树结构显示
/var/lib/iscsi/
|-- ifaces
|-- isns
|-- nodes
|-- send_targets
| `-- 172.25.254.220,3260
| `-- st_config
|-- slp
`-- static
7 directories, 1 file ###删除成功