處于運行中的服務器，因業務要求也許不允許重啟機器，而新添加的SCSI設備（主要是硬盤）如何實現熱插拔呢？

首先需要查看一下設備：

#cat /PRoc/scsi/scsiAttached devices:Host: scsi1 Channel: 00 Id: 00 Lun: 00  Vendor: NECVMWar Model: VMware IDE CDR10 Rev: 1.00  Type:   CD-ROM                           ANSI  SCSI revision: 05Host: scsi2 Channel: 00 Id: 00 Lun: 00  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0   Type:   Direct-access                    ANSI  SCSI revision: 02

可以看到有兩種設備：CD-ROM 和 Direct-Access 。

清楚SCSI設備后，就可以重新掃描新的設備了（例子是添加SCSI硬盤）：

# echo "scsi add-single-device 2 0 1 0" >/proc/scsi/scsi  echo "scsi add-single-device a b c d" >/proc/scsi/scsi中  a 表示 SCSI的設備號，上面的Host：scsi后的數字，新添加就是同類型的那個數字，虛擬機中的scsi硬盤就是Direct-Access  b 表示 CHANNEL號，上面的channel，基本都是0  c 表示 ID號，新添加就是上面同類型的Id值+1  d 是LUN號 一般都為0

# cat /proc/scsi/scsiAttached devices:Host: scsi1 Channel: 00 Id: 00 Lun: 00  Vendor: NECVMWar Model: VMware IDE CDR10 Rev: 1.00  Type:   CD-ROM                           ANSI  SCSI revision: 05Host: scsi2 Channel: 00 Id: 00 Lun: 00  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0   Type:   Direct-Access                    ANSI  SCSI revision: 02Host: scsi2 Channel: 00 Id: 01 Lun: 00  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0   Type:   Direct-Access                    ANSI  SCSI revision: 02

# fdisk -lDisk /dev/sda: 21.5 GB, 21474836480 bytes255 heads, 63 sectors/track, 2610 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x000ef79d   Device Boot      Start         End      Blocks   Id  System/dev/sda1   *           1          64      512000   83  linuxPartition 1 does not end on cylinder boundary./dev/sda2              64        2611    20458496   8e  Linux LVMDisk /dev/mapper/VolGroup-lv_root: 18.8 GB, 18832424960 bytes255 heads, 63 sectors/track, 2289 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000Disk /dev/mapper/VolGroup-lv_swap: 2113 MB, 2113929216 bytes255 heads, 63 sectors/track, 257 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000Disk /dev/sdb: 10.7 GB, 10737418240 bytes              <---這個就是新添加的硬盤255 heads, 63 sectors/track, 1305 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000