通常在你在虛擬機中添加一塊新硬盤時，你可能會看到新硬盤沒有自動加載。這是因為連接到硬盤的SCSI總線需要重新掃描來使得新硬盤可見。這里有一個簡單的命令來重新掃描SCSI總線和SCSI設備。下面這幾步在CentOS 7 和RHEL 7 中測試過。
在ESXi或者vCenter中添加一塊新的20G硬盤：
顯示當前磁盤分區：
[root@centos7 ~]# fdisk -l</p><p> 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
確定主機總線號
[root@centos7 ~]# ls /sys/class/scsi_host/
host0 host1 host2
重新掃描SCSI總線來添加設備
[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
驗證磁盤和分區并確保20GB硬盤已經添加了。在本例中，出現了下面這行 “Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors” 并且可以確認沒有重啟服務器就添加了新盤：
[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
