yes,i think it too:when you run fdisk,you delete partitions or erase the hdd
The Quirk is correct. Fdisk does nothing to the data on the drive. It only affects the partition table. The partition table tells the OS where the partitions begin, and end, and what kind of parition it is.
You can do whatever you want with fdisk, but until you
format partitions, the data remains intact. You can always go back into fdisk and reset the partitions back the way they were and the data is still there. I've
done this, both with MS FDISK and GNU/Linux FDISK.
In fact, it is prudent to keep a written copy of the partitions (what kind they are, where they begin and end) in case the partition table gets FUBARed. Boot with a Linux rescue disk like Tom's rootboot or Knoppix and rebuid the partition table. All data is intact. This saved my tail once.
Read
http://www.telenovela-world.com/~spade/linux/howto/Partition-Rescue/x31.html for some more information.
If you want to erase the drive, there are the ways mentioned above. The low-level format is the most turnkey solution because drive vendors usually supply a program to do this (either with the drive, or on their web site). But low-level formats may leave light ghostly images of the data that can be recovered... like faint traces of pencil writing on paper after using a rubber eraser on the entire page. That is why critical security facilities such as National Labs must store or destroy old hard drives.