How to detect newly added VM disk to Redhat 5.5?

Before Addition:

[root@unixhost ]# fdisk -l

Disk /dev/sda: 53.6 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 6527 52323705 8e Linux LVM
[root@unixhost]#

After Adding the disk from VM end

1) Run the following command:

#echo "- - -" > /sys/class/scsi_host/host0/scan
#fdisk -l


[root@unixhost]# echo "- - -" > /sys/class/scsi_host/host0/scan
[root@unixhost]# fdisk -l

Disk /dev/sda: 53.6 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 6527 52323705 8e Linux LVM

Disk /dev/sdb: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table
[root@unixhost]#



SDB - The new disk is detected now.