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Low-Level formating vs Zero-Filling an IDE Hard Drive

Very often, Zero-Filling an IDE hard drive is easy confused with Low-Level format. Let me start by saying that you don’t “low-level-format” IDE or ATA hard drives. This term is misnomer from old MFM hard drives days when drives could have the tracks and sectors defined using low-level-format.

All IDE or ATA drives we use today have their tracks and sectors preset at the factory and a real low level format would destroy the drive or at least slow it down drastically… in order words, you cannot redefine the tracks and sectors on these drives with low level format. At least it is fair to say that it is absolutely impossible to change the physical geometry of current IDE/ATA drives without destroying it. In conclusion, low-level-format is an old term that really doesn’t apply to today’s IDE/ATA hard drives.

Now, in today’s situation, there is a different approach in redefining the logical geometry of an IDE/ATA hard drive by building partition(s) on the drive. Keep in mind that there are also the differences between physical and logical geometry of a drive.

When people today use the term low-level-format, there is every indication that this is a real problem. Usually, one of the following issues may have occured:

• The drive has a boot sector virus and can no long be accessed to clean it off the drive

 

• The drive has begun to develope numerous bad sectors and they are increasing (usually seen when running Scan Disk)

 

• The drive has Linux, WindowsNT or other operating system installed which makes creating a Fat System on the drive incompatible with the new operating sytem to be installed.

 

What next… when people have these problems? They are usually wrongly told to low-level-format their hard drives. What really need to be done is reinitializing or mid-level format the drive.

ReInitializing an IDE/ATA Drive:

Now that we have the terminology straightened out, the next question would be… why does this matter? It is extremly important for you to know what exactly you’re doing to your drive.

When you reinitialize a hard drive, you basically use the appropriate tools to zero-fill the drive and as a result, cleaning every area of the hard drive. Most hard drive manufacturers provide on their web sites such utilities for downloading. One of such tools can be found on linux or UNIX operating systems and is simply called “dd”.

dd is the abbreviation for “dataset definition”. It is also jokingly said to stand for “disk destroyer” or “data destroyer”. since being used for low-level operations on hard disks, a small reversing the if and of parameters, can possibly result in the loss of all or some data on a hard disk.

    Example:

                 Using dd to wipe an entire disk with random data.
                 We are going to use a flash drive for thepurpose of this example.

                 first, we need to switch to root account

                 [stan@lnx]$su –

                 Enter the root password and type:

                 [root@lnx]#dd if=/dev/zero of=/dev/hdd

                 or

                 [root@lnx]#dd if=/dev/urandom of=/dev/hdd

                 or

                 for n in {1..7}; do dd if=/dev/urandom of=/dev/sdd bs=8b conv=notrunc; done

Once this process is complete, the drive will be void of any partitions. You will need to use FDISK for microsoft products to partition the drive and then format the new drive.

On a linux system, do the following:

[root@lnx]#fdisk /dev/sdd

Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won’t be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): p

Disk /dev/sdd: 1010 MB, 1010827264 bytes
32 heads, 61 sectors/track, 1011 cylinders
Units = cylinders of 1952 * 512 = 999424 bytes

Device Boot Start End Blocks Id System

Command (m for help): n
Command action
e extended
p primary partition (1-4): p
Partition number (1-4): 1
First cylinder (1-1011, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1011, default 1011): 1011

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): b
Changed system type of partition 1 to b (W95 FAT32)

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: If you have created or modified any DOS 6.x
partitions, please see the fdisk manual page for additional
information.
Syncing disks.

Now, format the new partition:

[root@lnx]#mkfs.vfat -F 32 /dev/sdd1