Low level format

  • Thread starter Thread starter Carl G
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Carl G

What is a low level format and how does it differ from regular formatting a
hard drive.
Thanks
 
A Low level Format (physical format) creates the tracks and sectors on a
Hard Disk.
It is done at the factory.

You cannot do this on newer drives from your PC.
Older MFM drives can be Low level formatted from your PC

High level format (the format command in dos and windows) is a logical
formatting that creates the data structures for the disk.

Regards
Mark Dormer
 
Carl said:
What is a low level format and how does it differ from regular formatting a
hard drive.
Thanks
Click to expand...

Low level format records the physical tracks, sectors and sector
interleave on the disk surface and optionally marks any surface defects
as unusable sectors.

A disk format using the operating system erases any existing address
tables, verifies that all sectors can be read reliably, marking
unreadable sectors as bad blocks (unless a quick format is performed,
then this function is skipped), and creates a new address table. It does
not erase any existing data on the data sectors themsleves, which is why
data recovery tools can sometimes recover information from an OS
formatted disk.

A low level format is done at the factory on modern drives and you
cannot perform it on them yourself. You can use a zero-fill utility
which writes zeros to every sector on the disk (which does erase data
from sectors) but this is not the same as a low level format, even
though some people mistakenly call it that. It is not a low level format
because it does not create the physical tracks, sectors nor sector
interleaves, it simply writes zeros to existing sectors.

In the old days of MFM, RLL, EDSI drives you had to perform a low level
format of a new disk before partitioning and formatting it with the
operating system. This was done by using DEBUG.COM or DEBUG.EXE (a
machine language program included in DOS) to load a format program from
the ROM on the disk controller adaptor card. In addition to manually
setting the number of tracks, sectors and sector interleave you could
also enter in bad sectors listed in a "bad track table" or "surface
defect list" usually pasted onto the drive case by the manufacturer or
supplied in a printout when it was QA tested at the factory. Since it
was fairly random as to where a low level format would create the first
sector of the first track on the spinning disk and all subsequent tracks
and sectors were then located based upon the location of the first
sector of the first track, it was a common practice back then to perform
a low level format over and over again on a disk with a large number of
surface defects, hoping that some surface defects would by chance fall
into the gaps between the beginning and ending of the tracks and the end
result being less storage area lost due to bad sectors. Remember, this
was back in the days of 10 to 60 MB (that's right, mere MegaBytes, not
GigaBytes!) of storage on these disks, so lost disk space due to bad
sectors was a big deal.

Steve
 
Hi Steve
The reason i asked that question is because i installed Raid 0 on my pc and
it was one of the options in the raid bios along with creating and deleteing
raid sets. My First Raid creation and of course it isn't working right.
Thanks for the info, I guess i won't click on low level format then,who
knows what it will do.
Thanks Steve
 
Carl said:
Hi Steve
The reason i asked that question is because i installed Raid 0 on my pc and
it was one of the options in the raid bios along with creating and deleteing
raid sets. My First Raid creation and of course it isn't working right.
Thanks for the info, I guess i won't click on low level format then,who
knows what it will do.
Thanks Steve
Click to expand...

Check the documentation for the controller, but I'd bet it is realy just
a zero-fill.

Steve
 
What is a low level format and how does it differ from regular formatting a
hard drive.
Thanks
Click to expand...

Nowadays, "low-level format" is just an inaccurate way of
describing a complete wipe of the harddrive by writing zeros to
all sectors. It returns the drive to its original condition, as it
was when you bought it.
 
Well, not exactly.
The current "low level" format is done only with a utility from the drive
Mfr. It can do such things as extensive drive testing, track and sector
sparing, set the drive size, and other things that vary greatly from mfr to
mfr. Some mfrs make such a utility available on request, or to an
authorized dealer or wholesaler, others keep it in house.
 
Chuck said:
Well, not exactly.
The current "low level" format is done only with a utility from the drive
Mfr. It can do such things as extensive drive testing, track and sector
sparing, set the drive size, and other things that vary greatly from mfr to
mfr. Some mfrs make such a utility available on request, or to an
authorized dealer or wholesaler, others keep it in house.
Click to expand...

As previously stated, such "low level format" utilities are mis-named. A
true low level format is exaclty what I described:

Low level format records the physical tracks, sectors and sector
interleave on the disk surface and optionally marks any surface defects
as unusable sectors.

Utilities availble from drive manufacturers are not capable of recording
the physical tracks, sectors and sector interleave on the disk surface.

Steve
 
Carl said:
What is a low level format and how does it differ from regular formatting a
hard drive.
Click to expand...

Your hard drive will NOT let you LLF it. However, many utils, including
some ones
from hard drive makers _improperly_ call their zero fill utils LLF
utils.

ie YOU cant LLF format a drive. YOU can, however, zero fill it and bring
it back to a
factory fresh state.

In other words, a zero fill or "llf" will wipe all data from the hdd. A
simple format
does NOT delete ANY data. A simple format simply makes all hard drive
space available
for NEW data to be written to the areas where your existing data already
exists.
 
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