Red Hat Enterprise Linux Server release 5.7 (Tikanga)
 

SCSI disk is not mounting in Red Hat Enterprise Linux Server release 5.7 (Tikanga), It is not showing in /dev and also fdisk -l, There is no disk in the name of sdXX

dmesg | grep scsi, fdisk -l, df -h , /dev/, and I tried with MAKEDEV
command also not showing anything,, here I am trying add some vitual scsi disk space to server.

echo "- - -" > /sys/class/scsi_host/(my hostname)/scan
output: no such a file or directory (there is no file is scsi_host folder)

Might be helpful to know what server hardware you are working with? Was this working before? Have you had other issues with the hardware. Some more information other than "Disk is not there" would be helpful.

Installed by using virtual hypervisor, here i am try to add the space virtually, configuration is
virtual machine 7
xeon, intel
intel xeon cpu e5-2620 @ 2.00ghz

What virtual method are you using? What controller have you set for your vms disk?

if i am correct i saw this problem happen when u are creating the profile for the rhel6 in the esx 4i when u create profile for rhel6 wrongly so create the profile with the option of "other64" that will make resolve the problem

windows 2008 server with hypervisor, Now I am using iscsi method i added the space to the server,

I have never setup a linux vm on windows hyper-v. I am not going to be much help on this.