What is zero filling?

Zero Filling

• Zero filling is a way to overwrite all data on a hard drive. An analogy would be putting new asphalt over an old highway. This snip is from the Seagate Website: "(Quick) will write over the beginning of the drive which includes the critical partition information, eliminating all partitions and information on the drive including the Master boot record. This is useful if you have a drive that has a corrupted partition or that you wish to erase to reinstalll a fresh operating system and new data. (Full) will write over the entire data area of the drive. This is useful if a drive has bad sectors that cannot be fixed by the operating system. This will also erase all the data on the drive, but it will take several hours."

• The simplest way to think of zero filling is setting every single byte of a storage device (RAM, HDD, whatever it may be), to null (character code 0). This effectively cleans the device of any data. This full text is online at: http://www.seagate.com/support/kb/disc/faq/ata_llfmt_what.html

• Zero filling removes the data on a HD 100%. This is especially useful in preventing data being stolen from your HD. After doing a zero filling, (apparently) no tool can retrive data from your HD and everything is permanently deleted.

• Zero filling is a low level hard disk management technique. As it suggests, it "fills the hard disk with zeros". By that, I mean that it magnetically prepares the disk to be a fresh disk, consisting of only zeros, no ones.

• There is another common definition for 'Zero filling'. Typically, in software development you will have numeric entry fields where significant digits are important. If those digits are not entered you will 'zero fill' them to ensure the entire value is filled. For example, if you have a field which is six long and enter '123' then you will zero fill to get a value of '000123'.
  
  
• The U.S. Marines released a data spec a while back that required for the drive to be zeroed completely 7 times. it seems there are some ways to get data back even if it's been zeroed. It just costs ungodly amounts of money.

First answer by ID0000000000. Last edit by Paulathomasson. Contributor trust: 18 [recommend contributor]. Question popularity: 302 [recommend question]