Uheldigvis faldt Klaus D. Mikkelsen over tastaturet og skrev derved
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> Alle 3 påstår at de gør.
Jeg faldt lige over dette:
Low-level formatting is the process of outlining the positions of the
tracks and sectors on the hard disk, and writing the control
structures that define where the tracks and sectors are. This is often
called a "true" formatting operation, because it really creates the
physical format that defines where the data is stored on the disk. The
first time that a low-level format ("LLF") is performed on a hard
disk, the disk's platters start out empty. That's the last time the
platters will be empty for the life of the drive. If an LLF is done on
a disk with data on it already, the data is permanently erased (save
heroic data recovery measures which are sometimes possible).
If you've explored other areas of this material describing hard disks,
you have learned that modern hard disks are much more precisely
designed and built, and much more complicated than older disks. Older
disks had the same number of sectors per track, and did not use
dedicated controllers. It was necessary for the external controller to
do the low-level format, and quite easy to describe the geometry of
the drive to the controller so it could do the LLF. Newer disks use
many complex internal structures, including zoned bit recording to put
more sectors on the outer tracks than the inner ones, and embedded
servo data to control the head actuator. They also transparently map
out bad sectors. Due to this complexity, all modern hard disks are
low-level formatted at the factory for the life of the drive. There's
no way for the PC to do an LLF on a modern IDE/ATA or SCSI hard disk,
and there's no reason to try to do so.
Older drives needed to be re-low-level-formatted occasionally because
of the thermal expansion problems associated with using stepper motor
actuators. Over time, the tracks on the platters would move relative
to where the heads expected them to be, and errors would result. These
could be corrected by doing a low-level format, rewriting the tracks
in the new positions that the stepper motor moved the heads to. This
is totally unnecessary with modern voice-coil-actuated hard disks.
Warning: You should never attempt to do a low-level format on an
IDE/ATA or SCSI hard disk. Do not try to use BIOS-based low-level
formatting tools on these newer drives. It's unlikely that you will
damage anything if you try to do this (since the drive controller is
programmed to ignore any such LLF attempts), but at best you will be
wasting your time. A modern disk can usually be restored to "like-new"
condition by using a zero-fill utility.
Older hard disks required periodic low-level formatting by the system
configurator or end-user. To facilitate this, low-level format
utilities were created. These are small programs written to control
the low-level formatting process for the hard disk. The hard disk
controller would normally include one of these programs in a ROM chip
in hardware, enabling access to the software without requiring any
drives to be running in the system, and thus avoiding a possible
"chicken and egg" quandary. In addition, more sophisticated,
third-party utilities were available that would perform an LLF and
also do other related features such as scanning for bad sectors or
analyzing the drive to determine an optimal interleave setting. These
would typically be loaded from a floppy disk.
Low-level formatting an older hard disk could be a rather complicated
procedure, particularly for one who was not very familiar with PCs and
hard disks. Various factors needed to be taken into account, such as
defect mapping and setting the interleave factor. The particular
conditions of the drive when formatting were also important: due to
the vagaries of stepper-motor actuators, doing an LLF when the drive
was very cold or very hot could lead to errors when the drive returned
to a more normal temperature. Even the orientation of the drive when
it was formatted was an issue.
As I have said (probably too often, sorry) modern drives do not need
to be low-level formatted by the end user, and in fact cannot be LLFed
outside the factory due to their precision and complexity. However, it
seems that the need to LLF hard disks on the part of users has never
gone away. Like some primordial instinct, many PC users seem to have a
fundamental desire to LLF their modern disks. Maybe it is built into
the genetic code in some way yet undiscovered. ;^) In fact, even if it
were possible, the vast majority of the time that someone "needs" to
LLF a hard disk today, it is not really necessary. Many users jump
quickly to wanting to try an "LLF" whenever they have a problem with
their hard disk, much the way many jump to re-installing their
operating system whenever it gives them trouble.
Hard drive manufacturers have created for modern drives replacements
for the old LLF utilities. They cause some confusion, because they are
often still called "low-level format" utilities. The name is incorrect
because, again, no utility that a user can run on a PC can LLF a
modern drive. A more proper name for this sort of program is a
zero-fill and diagnostic utility. This software does work on the drive
at a low level, usually including the following functions (and perhaps
others):
a.. Drive Recognition Test: Lets you test to see if the software can
"see" the drive. This is the first step in ensuring that the drive is
properly installed and connected.
b.. Display Drive Details: Tells you detailed information about the
drive, such as its exact model number, firmware revision level, date
of manufacture, etc.
c.. Test For Errors: Analyzes the entire surface of the hard disk,
looking for problem areas (bad sectors) and instructing the integrated
drive controller to remap them.
d.. Zero-Fill: Wipes off all data on the drive by filling every
sector with zeroes. Normally a test for errors (as above) is done at
the same time.
When most users today talk about "low-level formatting" a drive, what
they are really talking about is doing a zero-fill. That procedure
will restore a functional drive (that is, one that does not have
mechanical problems) to the condition it was in when received from the
factory. There are occasions when a modern hard disk can become so
badly corrupted that the operating system cannot recover it, and a
zero-fill can help in this situation. Stubborn boot sector viruses for
example can be hard to eradicate without resorting to low-level
intervention. Since the zero-fill cleans all programs and data off the
drive it will get rid of almost any data-related problem on the drive,
such as viruses, corrupted partitions and the like. Just remember that
it's a bit like burning down your house to get rid of termites: you
lose everything on the drive.
This type of utility can also be used to "hide" bad sectors by telling
the drive to remap them to its collection of spares. Just remember
that a drive that continues to "grow" bad sectors over time is one
whose reliability is highly suspect. I discuss this matter in more
detail here.
Warning: Only use a low-level zero-fill or diagnostic utility designed
for your particular hard disk. You can download one for free from your
drive manufacturer's web site. Even though damage probably won't
result from using the wrong program, you may lose data and you may
also complicate any warranty service you try to have performed on the
drive. (Technical support people at "Company X" generally don't like
to hear that you used a utility on their drive written by "Company
Y".)
Warning: Always back up your data before you use a low-level utility,
and make sure that you carefully follow all of the instructions
provided.
Warning: Never run a low-level disk utility from within a
multi-tasking operating system such as Windows 9x. Other programs
running in the background could interfere with the utility. Restart
the computer in MS-DOS mode first, or reboot the computer from a
floppy.
Kilde:
http://www.storagereview.com
Det burde vel forklare alt
Claus