Add a New Hard Disk Without Rebooting Guest

A rescan can be issued by typing the following command:
echo "- - -" > /sys/class/scsi_host/host#/scan
fdisk -l
tail -f /var/log/message

Replace host# with actual value such as host0. You can find scsi_host value using the following command:
# ls /sys/class/scsi_host
Output:

host0

Now type the following to send a rescan request:
echo "- - -" > /sys/class/scsi_host/host0/scan
fdisk -l
tail -f /var/log/message

How Do I Delete a Single Device Called /dev/sdc?

In addition to re-scanning the entire bus, a specific device can be added or existing device deleted using the following command:
# echo 1 > /sys/block/devName/device/delete
# echo 1 > /sys/block/sdc/device/delete

How Do I Add a Single Device Called /dev/sdc?

To add a single device explicitly, use the following syntax:

# echo "scsi add-single-device <H> <B> <T> <L>" > /proc/scsi/scsi

Where,

• <H> : Host
• <B> : Bus (Channel)
• <T> : Target (Id)
• <L> : LUN numbers

For e.g. add /dev/sdc with host # 0, bus # 0, target # 2, and LUN # 0, enter:
# echo "scsi add-single-device 0 0 2 0">/proc/scsi/scsi
# fdisk -l
# cat /proc/scsi/scsi
Sample Outputs:

Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0
  Type:   Direct-Access                    ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 01 Lun: 00
  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0
  Type:   Direct-Access                    ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 02 Lun: 00
  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0
  Type:   Direct-Access                    ANSI SCSI revision: 02

Step #3: Format a New Disk

Now, you can create partition using fdisk and format it using mkfs.ext3 command:
# fdisk /dev/sdc
# mkfs.ext3 /dev/sdc3

Step #4: Create a Mount Point And Update /etc/fstab

# mkdir /disk3
Open /etc/fstab file, enter:
# vi /etc/fstab
Append as follows:

/dev/sdc3               /disk3           ext3    defaults        1 2

Save and close the file.

Optional Task: Label the partition

You can label the partition using e2label. For example, if you want to label the new partition /backupDisk, enter
# e2label /dev/sdc1 /backupDisk