通常在你在虚拟机中添加一块新硬盘时，你可能会看到新硬盘没有自动加载。这是因为连接到硬盘的SCSI总线需要重新扫描来使得新硬盘可见。这里有一个简单的命令来重新扫描SCSI总线和SCSI设备。下面这几步在CentOS 7 和RHEL 7 中测试过。

在ESXi或者vCenter中添加一块新的20G硬盘：

　　显示当前磁盘分区：

代码如下:

[root@centos7 ~]# fdisk -l

Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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: 0x0006b96a

Device Boot Start End Blocks Id System

/dev/sda1 * 2048 1026047 512000 83 Linux

/dev/sda2 1026048 62914559 30944256 8e Linux LVM

Disk /dev/mapper/centos-swap: 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 / 512 bytes

Disk /dev/mapper/centos-root: 29.5 GB, 29536288768 bytes, 57688064 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

确定主机总线号

代码如下:

[root@centos7 ~]# ls /sys/class/scsi_host/

host0 host1 host2

重新扫描SCSI总线来添加设备

代码如下:

[root@centos7 ~]# echo "- - -" > /sys/class/scsi_host/host0/scan

[root@centos7 ~]# echo "- - -" > /sys/class/scsi_host/host1/scan

[root@centos7 ~]# echo "- - -" > /sys/class/scsi_host/host2/scan

验证磁盘和分区并确保20GB硬盘已经添加了。在本例中，出现了下面这行 “Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors” 并且可以确认没有重启服务器就添加了新盘：

代码如下:

[root@centos7 ~]# fdisk -l

Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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: 0x0006b96a

Device Boot Start End Blocks Id System

/dev/sda1 * 2048 1026047 512000 83 Linux

/dev/sda2 1026048 62914559 30944256 8e Linux LVM

Disk /dev/mapper/centos-swap: 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 / 512 bytes

Disk /dev/mapper/centos-root: 29.5 GB, 29536288768 bytes, 57688064 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: 21.5 GB, 21474836480 bytes, 41943040 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