linux挂载ISCSI磁盘

# linux挂载ISCSI磁盘
## 安装软件
```shell
yum install -y iscsi-initiator-utils
```

### 配置服务器IQN
```shell
[root@localhost ~]# vim /etc/iscsi/initiatorname.iscsi
# 修改InitiatorName后面的IQN名称，注意保持原格式例如
InitiatorName=iqn.2021-06.test.com:myfirstiscsi

[root@localhost ~]# systemctl enable iscsid
[root@localhost ~]# systemctl start iscsid
```

## 连接存储
### 1.发现
```shell
[root@localhost ~]# iscsiadm -m discovery -t st -p 存储控制器IP
192.168.192.1:3260,7938 iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1
```

### 2.登陆
```shell
[root@localhost ~]# iscsiadm -m node -T 存储IQN  -p 存储控制器IP:端口 -l
[root@localhost ~]# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1  -p 192.168.192.1:3260 -l
Logging in to [iface: default, target: iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1, portal: 192.168.192.1,3260]
Login to [iface: default, target: iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1, portal: 192.168.192.1,3260] successful.
```

### 3.登出
```
[root@localhost ~]# iscsiadm -m node -T 存储IQN  -p 存储控制器IP:端口 -u
[root@localhost ~]# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1  -p 192.168.192.1:3260 -l
Logging out of [iface: default, target: iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1, portal: 192.168.192.1,3260]
Logout of [iface: default, target: iqn.2006-08.com.huawei:oceanstor:2222222222222222::22222:192.168.192.1, portal: 192.168.192.1,3260] successful.
```

### 4. 删除
```shell
iscsiadm -m node -u -T IQN号 -p 存储控制器IP
iscsiadm -m node -o delete -T IQN号
```

## 连接多路径存储
如果是多路径存储，会通过iscsi多个控制器，这时候系统会出现与控制器数量相同的磁盘数如下：
```shell
Disk /dev/sda: 3.5 TiB, 3795677347840 bytes, 7413432320 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/sdb: 3.5 TiB, 3795677347840 bytes, 7413432320 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
```

可以看出来这两块盘的大小完全一致，实际上就是一块盘。那么正确使用他们的姿势就是通过`multipath`多路径软件将他们合并为一个多路径磁盘来使用。
### 安装multipath
```
[root@localhost ~]# yum install -y device-mapper-multipath
[root@localhost ~]# systemctl enable multipathd
[root@localhost ~]# systemctl start multipathd
[root@localhost ~]# systemctl status multipathd
● multipathd.service - Device-Mapper Multipath Device Controller
   Loaded: loaded (/usr/lib/systemd/system/multipathd.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2021-06-19 21:02:17 CST; 5s ago
  Process: 22001 ExecStartPre=/sbin/multipath -A (code=exited, status=0/SUCCESS)
  Process: 21999 ExecStartPre=/sbin/modprobe -a scsi_dh_alua scsi_dh_emc scsi_dh_rdac dm-multipath (code=exited, status=0/SUCCESS)
 Main PID: 22003 (multipathd)
   Status: "up"
    Tasks: 7
   Memory: 16.1M
   CGroup: /system.slice/multipathd.service
           └─22003 /sbin/multipathd -d -s

Jun 19 21:02:17 localhost systemd[1]: Starting Device-Mapper Multipath Device Controller...
Jun 19 21:02:17 localhost multipathd[22003]: --------start up--------
Jun 19 21:02:17 localhost multipathd[22003]: read /etc/multipath.conf
Jun 19 21:02:17 localhost multipathd[22003]: path checkers start up
Jun 19 21:02:17 localhost multipathd[22003]: mpatha: load table [0 7413432320 multipath 0 0 2 1 service-time 0 1 1 8:0 1 service-time 0 1 1 8:16 1]
Jun 19 21:02:17 localhost systemd[1]: Started Device-Mapper Multipath Device Controller.
```

### 1.查看磁盘
```shell
[root@localhost ~]# multipath -ll
mpatha (360022a11000dd76eaff3acb400000004) dm-2 HUAWEI,S5500T
size=3.5T features='0' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=1 status=active
| `- 2:0:0:0 sda 8:0  active ready running
`-+- policy='service-time 0' prio=1 status=enabled
  `- 3:0:0:0 sdb 8:16 active ghost running
```
从上面可以看出，mpatha这个磁盘下面包含了两块磁盘，`sda`和`sdb`，我们只需要格式化并使用`mpatha`这块磁盘就可以了。
磁盘在下面的位置：
```shell
[root@localhost ~]# ls -la /dev/mapper/mpatha
lrwxrwxrwx 1 root root 7 Jun 19 21:02 /dev/mapper/mpatha -> ../dm-2
```

### 2.为磁盘改名
如果不喜欢`mpatha`可以通过修改配置文件将磁盘改名，比如`vda`
```shell
# 查看磁盘mpatha的wwid
[root@localhost ~]# /etc/multipath/wwids 
# Multipath wwids, Version : 1.0
# NOTE: This file is automatically maintained by multipath and multipathd.
# You should not need to edit this file in normal circumstances.
#
# Valid WWIDs:
/360022a11000dd76eaff3acb400000004/

# 将下面的mpatha修改为想要的磁盘名称即可
[root@localhost ~]# cat /etc/multipath/bindings
# Multipath bindings, Version : 1.0
# NOTE: this file is automatically maintained by the multipath program.
# You should not need to edit this file in normal circumstances.
#
# Format:
# alias wwid
#
mpatha 360022a11000dd76eaff3acb400000004

# 修改完成后重启服务，多路径磁盘就完成重命名了。
```