The latest stable release of Red Hat Enterprise Linux is 6.1 named as Santiago. Now RHEL 6.1 does not come with NTFS filesystem already installed. So when you try to mount a Windows USB external HDD that has NTFS filesystem, there is a error thrown filesystem ntfs not found. So generally any one would type “yum install ntfs” in the terminal but it seems that this too does not work.
Following is a simple solution to install ntfs-3g and mount the NTFS filesystem disk:
Step 1.: Download and install ntfs-3g either by building the source(./configure… make… make install) or finding an rpm for your distribution from here.
Step 2: mount the Hard Disk using the following command:
mount -t ntfs-3g /dev/sda1 /mnt/windows
note that the filesystem should be mentioned as ntfs-3g and not just ntfs.
Further Reading:
{apilevel.com} 
yum install ntfs-3g worked fine in CentOS 6.4