I think ntfs file-system will not support in CentOS. Once I faced same issue.
To mount ntfs file-system in CentOS follow below method.
Make sure you have the rpmforge or epel repo installed.
To enable epel repositary follow this method
For 32 bit
wget http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
rpm -ivh epel-release-6-8.noarch.rpm
For 64 bit
wget http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -ivh epel-release-6-8.noarch.rpm
yum update
yum install fuse fuse-ntfs-3g
yum install ntfs-3g
Then Mount the External HDD
mount -t ntfs-3g /dev/disk /mnt/disk