Extending a file system

Assumptions: VM server runnig RHEL 6 with SCSI drives /dev/sda and d/dev/sdb are already in use and a volume group named appvg which has logical volume, lv1 defined. A Virtual Disk 20G is size has been presented the the VM.

The current procedures I have for extending a ext3 file system is:

1. Scan in the new LUN, say /dev/sdc
2. Use fdisk to create a partition and type, say /dev/sdc1 as type 8e
3. Create new physical volume, pvcreate /dev/sdc1
4. Extend the volume group, vgextend appvg /dev/sdc1
5. Extend the logical volume, lextend -L +20G /dev/appvg/lv1
6. Extend the file system, resize2fs /dev/appvg/lv1

I hear rumor that under RHEL 6, creating a partition on the scanned LUNs is no longer necessary and that I can use vgextend appvg /dev/sdc without the need of running pvcreate first and that I can use the -r parm on lvextend to resize the file system.

Can I now just run the following commands?:

1. Scan the new LUN, say /dev/sdc
2. vgextend appvg /dev/sdc
3. lvextend -L +20G -r /dev/appvg/lv1

If so why is a partition no longer needed on a LUN and is use of the lvextend -r only for ext4 file systems?