The term low level format comes up from time to time on PCBUILD and
generates a lot of different and often erroneous explanations.
Let me see if I can throw some light on low level formats.

>First comment:
>you  never do a low level format. This is done at the factory. It's a very
>last
>resort. It sets the bits back to zero or sometimes called "zero fills" the
>drive.
>Gerald kearns

This is incorrect.

  SCSI devices are still low level formatted by end users..in fact on older
SCSI drives you may have to use your SCSI adaptor to low level format a
particular SCSI drive in order for it to work with a particular SCSI
controller.

For AT and EIDE drives the term "low level" is a bit of a misnomer. The low
level process first used years ago in mfm hard drives bears little
resemblance to what we now call a "low level format" for today's ata (ide)
drives. A better name for today's low level formatting utility is
intermediate- or mid-level formatting. This is sometimes referred to as the
"initialize" or "re-initialize" process. The basic purpose of a mid-level
format is to erase everything, including the boot sector, currently on the
drive.

Re-initializing a drive is done by Writing Zeroes to the entire surface of
the drive and optionally using a manufacturer utility to perform extensive
read write tests. Theoretically any Write Zero utility should work on any
drive but you might as well use a specific manufacturer provided one. Every
time I have done one I have always checked the manufacturer's web site and
they always have one for their drives. Using a manufacturers utility you
will also be able to perform extensive read write error testing AFTER
performing the Write Zero..... something no third party software could do.
While the Write Zero utility doesn't take that long , error testing
particularly with extensive pattern scanning can take a very long
time...even days.

Why would you want to write zeroes to a drive? To cleanse the drive ....and
after running the read write tests you will have a drive that you know is
restored to the condition it was in when it left the factory.

Writing Zeros to a drive is often the only way you can remove a corrupt
Partition Table or Master Boot Record and this is why I have used it
although I often use the zero write utility in order to remove everything
from it prior to creating a completely new setup.

The most common reasons to low level format an ata (ide) hard drive are:

The drive has contracted a virus that cannot be removed without destroying
the boot sector.
The drive is developing bad sectors at an increasing rate.
Corrupt Partition table or MBR
You are changing from one operating system to another and wish to remove
everything from the drive.

Be aware that once you Write Zeros to a drive there is no going back.
There is no software on earth that can restore the data.

Mark Rode
The NOSPIN Group

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