AwardsA. This experience
may answer your question.
I got a call from a client whose son evidently
went to the BIOS and
started to preformat (low level format) their
Quantum Bigfoot 3.2GB hard
drive. He then became impatient and reset the
machine. He had also
jumpered it as a slave (was originally master)
although he claimed not
to know how that happened.
Re-running the preformat failed, although the
BIOS still detects all the
drive parameters. FDISK reports that there are
no partitions defined.
When I try to create one, it says "No space to
create a DOS partition".
If I try to delete one, it says "No partitions
to delete".
I have set it up as a secondary drive on a W95
system with Norton
Utlities, but Disk Doctor will not detect the
drive even though BIOS
does.
Dave said: Hi
here's one suggestion ......
try formatting the drive with a drive overlay
program. I know quantum has
one on their web site.
then maybe you can format normally.
If you can't find it gimme a yell and I'll dig
mine up.
best of luck Dave
Paul added: Well, looking at my PC Repair manual,
it says that each manufacturer provide
specific software for low-level formatting and
defect management.
Apparently, there are some special codes that
the manufacturer's software
passes to the controller to allow it to low-level
format the hdd. Without
these codes (built into the program I guess)
it won't do the job properly -
I'd hazzard that the BIOS low-level format routines
are generic and won't
include those codes.
My book also provides a list of manufacturers
who can provide this low level
format s/w. Now, my book is a few years out of
date and Quantum isn't
listed. Which isn't to say they don't now, or
the list is correct. The best
place to start is their website, which is http://www.quantum.com/
Good luck.
Chris said: I just wanted to mention that if you
are going to low-level format a drive
make sure it is not an IDE drive. IDE drives
should *never* be low-level
formatted, use only the standard DOS format (FORMAT.EXE).
Cheers,
Chris.
Greg said: Hi guys;
Unfortunately
I have to agree with everyone on the fact that the drive is
useless. It really isn't even worth sending
back to the factory, because
even if they can repair the damage it would cost
more than just replacing
the drive. I would suggest finding another
3-5 Gig harddrive for them. You
should be able to find one for under US$75.
Greg
John tried ZEROFILL.EXE and responded: Thanks.
I tried that, but zerofill doesn't recognise the drive even when
BIOS does. That makes it impossible to format.
Interestingly, there was
a comment in the zerofill instructions which
is directly relevant to
what happened in this case. Here it is in full:
Q. Why can't I just use the low-level formatter I already have?
A. ZERO FILL is the only utility which is guaranteed
not to damage the
servo and drive specific information written
to the Quantum hard disk
drive. Many low-level format utilities can potentially
erase this drive
specific information resulting in a non-functioning
drive. The use of
low-level routines on Quantum ATA.IDE disk drives
may void your
warranty.
So the moral of the story is: If your BIOS has
a low level format
utility, STAY AWAY FROM IT, unless you know for
certain it's ok to use
on your drive(s).
Chris added: Some older drives and their related
software provided low-level format
utilities but modern IDE (& SCSI) drives
come from the factory already
low-level formatted and optimised for their inbuilt
controllers. IDE means
Integrated Drive Electronics, the controller
is unique to the drive. If you
again run a low-level format you destroy the
specific drive/controller
format and the drive will never work optimally
(or even maybe at all) again.
The rule-of-thumb is: NEVER low-level format,
it's too dangerous.
Scott McNay answered:
The "index mark" is the beginning of each track. In 8" and 5.25"
floppies, it's the small hole next to the hub ring. In 3.5" floppies,
there's a rectangular hole in the hub that the drive mechanism sticks
into to hang onto the disc, and is also used as the index mark.
Note that the ID VFO Lock bytes, Data Sync VFO Lock bytes, and
Inter-Record Gap bytes serve as padding. They can be overwritten by
another sector's header or data without much concern. This helps
account for subtle variations in drive speed, expansion and
contraction of parts due to temperature differences, aging, and so
forth. Thus, if the drive is slow at recognizing the ID VFO Lock, it
may be slow at starting to write the new Data Sync VFO Lock, which
would make it appear to be more than 13 bytes long, and everything
else would be pushed down, so that the re-written Inter-Record Gap
would overlap the next ID VFO Lock -- which is exactly what is
designed to happen. Note that modern drives do not necessarily use the
same sector layout, but this gives you the idea.
The ID VFO Lock, Sync Byte, Address Mark FE, Cylinder #, Head #,
Sector #, CRC, and Write Turn-off Gap are normally only written or
overwritten during a true low-level format operation.
Floppies are nearly identical to what is described here, and probably
the same for floppy-like devices such as ZIP drives. I suspect that
tape drives are similar also, and for the same reason: to record
digital random-access data reliably on sequential-access analog
devices. (each individual track is accessed sequentially).
Michael read the above and said: Actually, there are a number of safe low-level formatters out there. I've found one that
works with ALL drives, particularly IDE drives and works EVERY time. I've been doing this for the
past 5 years without one ever having a problem afterwards. If you go to Maxtor's website and
download a program called powermax, that does a wonderful job low-level formatting ANY brand
drive. If you can't find it, and you'd like to have it, post a comment up here and I'll come back
with a place where you can download it from me. Cheers and good luck.
PcCowboy asked:
I was wondering how a low level format works. I know what it is for
but not how it does it.
You see my son is taking a class at school and his teacher told him
something that i think is pure stupid. He said that in low level format
the heads touches the surface of the platers, polishing the surface
smoothing out all the defects. Now this doesn't make sense.
When the heads touch the surface, it's called a head crash, and is
generally an undesirable event.
There is a lot of hype associated with low-level formatting. Low-level
formatting is simply a matter of rewriting the sector boundaries,
while high-level formatting writes to the sectors in the normal way
and consists of rewriting the sector contents so that a new file
system is in place. To rephrase, low-level formatting writes the
entire track all at once. whereas high-level formatting and normal
writing to the drive look for the beginning of each sector, then write
all of the data for that sector, then look for the beginning of the
next sector, etc.
When hard drives first became available to the general public,
low-level formatting was mandatory, because the controller did not
come with the drive. Different controllers had slightly different
results with different model drives, and if the controller died and
needed replacing, the data might be unreadable, due to differences
between the controllers. Thus, a low-level format was needed to write
the sectors in the location and manner that the controller wanted.
Since the older drives and controllers could not adjust for the
effects of aging, a low-level format was needed on occasion to adjust
for that, also.
At about the time when the AT computers started coming out, a new type
of drive became available also, called the IDE (Integrated Drive
Electronics) or ATA (AT Attachment) drive, in which the controller was
built into the drive, and the computer only needed a simple interface
(paddle) board. Name-brand computers had this built in, and white-box
computers did not generally have it built in until the pentium boards
started coming out.
Drive manufacturers started putting different numbers of sectors on
each track, depending upon the length of the track. At this point,
low-level formatting became dangerous, since it would put the same
number of sectors on each track. Thus the drive could lose a serious
amount of capacity. Also, the newer drives had defect management,
which required that an area of the drive be set aside to manage the
defects; low-level formatting would overwrite this also. As a result,
low-level formatting became discouraged, and some drives disallowed
it.
Nowadays, when someone talks about low-level formatting, what they
really mean is overwriting all of the sectors in the normal way, which
has the side-effect of causing the defect management system to swap
out bad sectors. Bad sectors cannot be swapped out by reading the
drive, which is what is typically done by high-level formats. Because of
this redefinition, one should be careful about utilities that claim to
do low-level formatting, because they might REALLY low-level format
the drive, which is now something that you should do only if you're
about to throw the drive into the trash. If the drive is under
warranty, don't even think about it, as that will usually void the
warranty.
In case there's any confusion, I should clarify that a sector boundary
is just more data. It's just that the drives are generally careful to
only write within the area that is set aside for the data, exactly the
same as you'd do when you dub a cassette tape.
I used to have a table showing the structure of a sector on a floppy.
It records what sector # the sector is, how long the sector is, and so
forth, plus a large empty spot for the data itself, and another empty
spot between sectors, so that the drive won't accidentally overwrite
the next sector. In a low-level format, all of this gets rewritten.
If I can find the table, I'll post it. It might have been in one of
the files that I sent John.
--Scott.
PS:Here's the sector layout; I found it in a file that I last updated 8
years ago. It's info that's extremely hard to find nowadays:
Sector format for a typical hard drive:
Bytes
Name
Desc
16
Post Index Gap
=4E, immediately after index mark
571(s)
Sector(s)
693
Pre-Index Gap
=4E
Bytes
Name
Desc
13
ID VFO LOCK
=00
1
SYNC BYTE
=A1
1
ADDRESS MARK
=FE
2
CYLINDER NUMBER
??, cylinder #, 0-?
1
HEAD NUMBER
??, head #, 0-?, High bit on = bad
2
CRC
ID CRC (corrupted means marked bad by factory)
3
WRITE TURN-ON GAP
=00
13
DATA SYNC VFO LOCK
=00
1
SYNC BYTE
=A1
1
ADDRESS MARK
=F8
512
DATA
??
2
CRC
DATA CRC
3
WRITE TURN-OFF GAP
=00
15
INTER-RECORD GAP
=00
