如何不用重启在CentOS7/RHEL7虚拟机中添加一块新硬盘

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。

1. 在ESXi或者vCenter中添加一块新的20G硬盘：

   

2. 显示当前磁盘分区：

   [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

    

3. 确定主机总线号

   [root@centos7 ~]# ls /sys/class/scsi_host/
   host0 host1 host2

    

4. 重新扫描SCSI总线来添加设备

   [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

    

5. 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：

   [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