iSCSI概念
iSCSI(Internet SCSI)支持从客户端(发起端)通过IP向远程服务器上的SCSI存储设备(目标)发送SCSI命令。iSCSI限定名称用于确定发起端和目标,并采用iqn.yyyy-mm.{reversedomain}:label的格式。默认情况下,网络通信是至iSCSI目标上的端口3260/tcp的明文。
iSCSI发起端:需要访问原始SAN存储的客户端。
iSCSI目标:从iSCSI服务器提供的远程硬盘磁盘,或“目标门户”
iSCSI目标门户:通过网络向发起端提供目标的服务器。
IQN:“iSCSI限定名称”。每个发起端和目标需要唯一名称进行标识,最好的做法是使用一个在Internet上可能独一无二的名称。
1.
iscsi是直接对设备进行共享的服务
2.启动iscsi共享设备
在server端：
1）实验前在服务端建立lvm设备
[root@server13 ~]# fdisk /dev/vdb##建立lvm设备
n→p→回车→回车→+1000M→p→t→8e→p→wq
[root@server13 ~]# partprobe
[root@server13 ~]# pvcreate /dev/vdb1##共享一个lv
Physical volume "/dev/vdb1" successfully created
[root@server13 ~]# vgcreate vg0 /dev/vdb1
Volume group "vg0" successfully created
[root@server13 ~]# vgdisplay
[root@server13 ~]# lvcreate -l 249 -n iscsi_storage vg0
Logical volume "iscsi_storage" created
测试：
[root@server13 ~]# lvs##lvm设备的成功建立
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
iscsi_storage vg0 -wi-a----- 996.00m
2）服务的安装与开启
[root@server13 ~]# yum install targetcli.noarch ##安装iSCSI目标软件包
[root@server13 ~]# systemctl enable target.service ##启动服务
ln -s '/usr/lib/systemd/system/target.service' '/etc/systemd/system/multi-user.target.wants/target.service'
[root@server13 ~]# systemctl start target.service
[root@server13 ~]# systemctl stop firewalld.service
3）服务端的配置
[root@server13 ~]# 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'.
/> ls
o- / ....................................................... [...]
o- backstores ............................................ [...]
| o- block ................................ [Storage Objects: 0]
| o- fileio ............................... [Storage Objects: 0]
| o- pscsi ................................ [Storage Objects: 0]
| o- ramdisk .............................. [Storage Objects: 0]
o- iscsi .......................................... [Targets: 0]
o- loopback ....................................... [Targets: 0]
/> /backstores/block create server1storage /dev/vg0/iscsi_storage ##和逻辑卷建立联系，把/dev/vg0/iscsi_storage用server1storage表示
Created block storage object server1storage using /dev/vg0/iscsi_storage.
/> /iscsi create iqn.2017-06.com.example:strage1 ##创建iqn服务的名称（每个发起端和目标需要唯一名称进行标识）
Created target iqn.2017-06.com.example:strage1.
Created TPG 1.
/> ls
o- / ....................................................... [...]
o- backstores ............................................ [...]
| o- block ................................ [Storage Objects: 1]
| | o- server1storage [/dev/vg0/iscsi_storage (996.0MiB) write-thru deactivated]
| o- fileio ............................... [Storage Objects: 0]
| o- pscsi ................................ [Storage Objects: 0]
| o- ramdisk .............................. [Storage Objects: 0]
o- iscsi .......................................... [Targets: 1]
| o- iqn.2017-06.com.example:strage1 ................. [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.2017-06.com.example:strage1/tpg1/luns create /backstores/block/server1storage ##创建逻辑单元号
Created LUN 0.
/> /iscsi/iqn.2017-06.com.example:strage1/tpg1/acls create iqn.2017-06.com.example:server1storagekey ##创建访问控制列表
Created Node ACL for iqn.2017-06.com.example:server1storagekey
Created mapped LUN 0.
/> /iscsi/iqn.2017-06.com.example:strage1/tpg1/portals create 172.25.13.11 ##加密（默认情况下,网络通信是至iSCSI目标上的端口3260/tcp的明文）
Using default IP port 3260
Created network portal 172.25.13.11:3260.
/> exit
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json
查看：
[root@server13 ~]# targetcli
targetcli shell version 2.1.fb34
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help'.
/> ls
o- / ....................................................... [...]
o- backstores ............................................ [...]
| o- block ................................ [Storage Objects: 1]
| | o- server1storage [/dev/vg0/iscsi_storage (996.0MiB) write-thru activated]
| o- fileio ............................... [Storage Objects: 0]
| o- pscsi ................................ [Storage Objects: 0]
| o- ramdisk .............................. [Storage Objects: 0]
o- iscsi .......................................... [Targets: 1]
| o- iqn.2017-06.com.example:strage1 ................. [TPGs: 1]
| o- tpg1 ............................. [no-gen-acls, no-auth]
| o- acls ........................................ [ACLs: 1]
| | o- iqn.2017-06.com.example:server1storagekey [Mapped LUNs: 1]
| | o- mapped_lun0 ...... [lun0 block/server1storage (rw)]
| o- luns ........................................ [LUNs: 1]
| | o- lun0 [block/server1storage (/dev/vg0/iscsi_storage)]
| o- portals .................................. [Portals: 1]
| o- 172.25.13.11:3260 .............................. [OK]
o- loopback ....................................... [Targets: 0]
/> exit
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json
在客户端连接：
[root@desktop13 ~]# vim /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.2017-06.com.example:server1storagekey
[root@desktop13 ~]# systemctl restart iscsi
[root@desktop13 ~]# fdisk -l
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
[root@desktop13 ~]# iscsiadm -m discovery -t st -p 172.25.13.11 ##查找iscsi服务器所提供的iscsi目标
172.25.13.11:3260,1 iqn.2017-06.com.example:strage1
[root@desktop13 ~]# iscsiadm -m node -T iqn.2017-06.com.example:strage1 -p 172.25.13.11 -l ##登录服务器上的iscsi目标
Logging in to [iface: default, target: iqn.2017-06.com.example:strage1, portal: 172.25.13.11,3260] (multiple)
Login to [iface: default, target: iqn.2017-06.com.example:strage1, portal: 172.25.13.11,3260] successful.
测试：
[root@desktop13 ~]# fdisk -l ##客户端上出现一个新硬盘设备
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 /dev/sda: 1044 MB, 1044381696 bytes, 2039808 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: 0xfe173449
Device Boot Start End Blocks Id System
/dev/sda1 8192 2039807 1015808 83 Linux
3.自动挂载
[root@desktop13 ~]# vim /etc/fstab
10 UUID=2da90fa4-582e-4c16-863a-bd6d83587e8f /mnt xfs defaults,_netdev 0 0
##_netdev表示开机挂载之前先启动网络服务
4.删除
[root@desktop13 ~]# umount /mnt/
[root@desktop13 ~]# tree -C /var/lib/iscsi//var/lib/iscsi/
├── ifaces
├── isns
├── nodes
│ └── iqn.2017-06.com.example:strage1
│ └── 172.25.13.11,3260,1
│ └── default
├── send_targets
│ └── 172.25.13.11,3260
│ ├── iqn.2017-06.com.example:strage1,172.25.13.11,3260,1,default -> /var/lib/iscsi/nodes/iqn.2017-06.com.example:strage1/172.25.13.11,3260,1
│ └── st_config
├── slp
└── static
10 directories, 2 files
[root@desktop13 ~]# iscsiadm -m node -T iqn.2017-06.com.example:strage1 -p 172.25.13.11 -u ## 登出iSCSI目标,以暂时断开连接
Logging out of session [sid: 1, target: iqn.2017-06.com.example:strage1, portal: 172.25.13.11,3260]
Logout of [sid: 1, target: iqn.2017-06.com.example:strage1, portal: 172.25.13.11,3260] successful.
[root@desktop13 ~]# iscsiadm -m node -T iqn.2017-06.com.example:strage1 -p 172.25.13.11 -o delete ## 删除iSCSI目标的本地记录,以永久断开连接
在服务端删除：
[root@server13 ~]# targetcli
targetcli shell version 2.1.fb34
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help'.
/> clearconfig confirm=True
All configuration cleared
/> exit
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json
测试：
[root@desktop13 ~]# tree -C /var/lib/iscsi//var/lib/iscsi/
├── ifaces
├── isns
├── nodes
├── send_targets
│ └── 172.25.13.11,3260
│ └── st_config
├── slp
└── static