以在linux系统中添加一块300G磁盘为例

# 在Linux系统中执行lsblk命令时不显示新添加的磁盘:
[root@localhost ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk
├─sda1            8:1    0    2M  0 part
├─sda2            8:2    0  200M  0 part /boot     
└─sda3            8:3    0 19.8G  0 part
  ├─centos-root 253:0    0 17.8G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]    
sr0              11:0    1 1024M  0 rom

一、查看系统中的iscsi服务器信息

[root@localhost ~]# ll /sys/class/scsi_device/
总用量 0
lrwxrwxrwx. 1 root root 0 9月  19 20:59 2:0:0:0 -> ../../devices/pci0000:00/0000:00:15.0/0000:03:00.0/host2/target2:0:0/2:0:0:0/scsi_device/2:0:0:0
lrwxrwxrwx. 1 root root 0 9月  19 20:59 3:0:0:0 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:01.0/ata3/host3/target3:0:0/3:0:0:0/scsi_device/3:0:0:0

[root@localhost ~]# ls /sys/class/scsi_host/
host0  host10  host12  host14  host16  host18  host2   host21  host23  host25  host27  host29  host30  host32  host5  host7  host9
host1  host11  host13  host15  host17  host19  host20  host22  host24  host26  host28  host3   host31  host4   host6  host8

从上面的信息中可以看到系统中包含host2、host3两个iscsi

二、重新扫描磁盘

[root@localhost ~]# echo "- - -" > /sys/class/scsi_host/host3/scan

三、验证扫盘是否生效

[root@localhost ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk
├─sda1            8:1    0    2M  0 part
├─sda2            8:2    0  200M  0 part /boot     
└─sda3            8:3    0 19.8G  0 part
  ├─centos-root 253:0    0 17.8G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]  
sdb              8:3 0  0   300G   0 disk
sr0              11:0    1 1024M  0 rom

看到新添加的大小为300G的sdb说明识别成功，若仍未识别可尝试重新扫盘host2