A little about Format Command
First of all, (you don't have to FDISK/Partition your H-D first,
because you might just want to Restore (Clean-Up) Windows or
just want a extra storage area, so just FORMAT/Re-FORMAT it and
it's done.
Formatting is the process of writing marks
on the Hard Drive or (removable) Magnetic media that are used
to mark tracks and sectors. Before a disk is formatted, its magnetic
surface is a complete mess of magnetic signals. When it is formatted,
some order is brought into the chaos by essentially drawing lines
where the tracks go, and where they are divided into sectors.
The actual details are not quite exactly
like this, but that is irrelevant. What is important is that
a disk cannot be used unless it has been formatted. The terminology
is a bit confusing here: in MS-DOS, the word formatting is used
to cover also the process of creating a file system. There, the
two processes are often combined, especially for floppies. Where
the distinction needs to be made, the real world Unix techies
call formatting (low-level formatting, while making the file
system is called high-level formatting) and we combine the two
and call it formatting.
Ok, you've learned that your platter (disk)
is a mass storage device generally made of metal, covered with
a thin layer of iron oxide of which has good magnetic properties.
Computers record data in bits, 8 bits to a byte and 512 bytes
to a sector. The Windows OS knows where all your stuff is at
upon request. Even the smallest hard drive can store millions
of bits and must be organized---called (formatting).
First, a hard drive has to be physically
formatted before it can be logically formatted. This (low-level)
formatting is done by the drive manufacturer (IDE) and divides
the platter into tracks, sectors and cylinders----these are called
physical elements. Tracks are circular paths around your disk
and are identified by a number starting with (0) at the outer
edge. The set of tracks that lie at the same distance from the
center on all sides of all platters are called a cylinder. Tracks
are divided into areas called sectors.
Sectors are usually formatted to contain
4096 bits or 512 bytes. After this physical format--it's ready
for logical formatting.
Logical formatting places a file system
on your disk and a file system allows an operating system like
(Windows-95) to use this space to store and retrieve files. So,
this is what you do is a logical formatting using it's operating
utility.
This means you can format a Hard-Drive
and use it right away for a storage container just like you've
been doing on the floppies since you know when, then use it as
a back-up data area or what ever. A disk can be divided into
partitions and then formatting is applied.
After you partition and format---it's called
a (volume). This is why you should give it a name or (label)
so you can identify it.
So, you now (hopefully) understand why
you have to format.
Format Switches
FORMAT = places a file system on the disk
for storage or a operating system.
FORMAT /c -
Causes FORMAT to retest bad clusters, otherwise FORMAT will mark
the clusters as bad but will not retest them.
FORMAT /s = prepares a partition
or disk to make it active or bootable.
FORMAT /q
=this is mostly unknown but seems to work if your having problems
getting the W95 setup to work (not recommended unless it's a
last ditch effort).
FORMAT /U
= Does a unconditional format, so do the SYS C: to get system
files -- then a through scandisk to fix any errors. This FORMAT
/U parameter performs an UNCONDITIONAL format, which DESTROYS
every byte of data on a disk by overwriting it with.
FORMAT /U/S
= Combination Format Unconditionally then transfer System Files.
WARNING: You
CANNOT UNFORMAT a disk formatted using the /U option!
FORMAT /SELECT
/U This particular combination of FORMAT.COM parameters makes
a disk UNREADABLE! WARNING: DO NOT use these two FORMAT switches
TOGETHER on ANY drive!
FORMAT /Z:n
formats a FAT32 drive with a cluster size of n times 512 bytes.
Meaning: drive: = your hard drive letter (C:, D:, etc). n = number
of sectors per cluster multiplied by 512 = cluster size in bytes.
Examples: n = 1 creates a 512 bytes cluster; n = 2 creates a
1024 bytes (1 KB) cluster; n = ? creates a ? x 512 = ???? bytes
(???? bytes : 1024 = ? KB) cluster.
NOTE: Almost all manufactures of hard drives
(these days) come formatted and most will come with a program
disk for formatting, partitioning and moving your system from
your old hard drive to the new one.
Low-Level Formatting Explained:
Cylinder: concentrical tracks on
one or more disksides the harddrive's read/write head can be
positioned over. The heads are mounted on a "fork"
which positions all heads in a certain cylinder position.
Head Side:
this refers to the harddrive's read/write head currently active.
Since most harddrive's have at least 2 heads also the term Side
is used for referring which disk and side has an "active"
head over it.
Track:
the combination of the cylinder all heads are over, and the selected
head.
Sector:
the smallest unit that can be read from/written to a disk. Without
special drivers, DOS and windows can only cope with 512-byte
sectors.
BootSector:
(ie:, the first sector in each partition). It stores information
like the number of sectors/cluster, the partitionsize, the number
of sectors/FAT and the number of sectors in the partition. Also
it has code to load IO.SYS and MSDOS.SYS which are used by the
boot process which is of course only used in the active, primary
partition that is used to boot.
Formatting & Low-Level Formatting
This is very confusing to most people.
Formatting a floppy generally means that BOTH a low-level and
a high-level format take place. The low-level format overwrites
full tracks consisting of multiple sectors, headers and trailers.
Each sector is preceded by a header and gets a trailer written
behind it. Only the sectors and trailers are updated when you
copy a file to the floppy (effectively writing sectors), the
headers are used for finding the start of each sector on the
track and are only read from (except during a format operation).
The low-level format calculates a CRC-checksum (CRC = Cyclic
Redundancy Check, a special algorithm that is very sensitive
to even the slightest change in data) from each sector it writes,
and writes that calculated checksum to the trailer. After low-level-formatting
each track, the format program simply reads all sectors and trailers
in it, recalculates the checksum from each sector and compares
it to the checksum in the trailer. If they don't match, the sector
is considered "bad". It stores all bad sector locations
in RAM for later use. After finishing ALL tracks on both sides,
the format program will do a high-level format of the floppy.
That means that it will write a proper bootsector, clear both
FAT's and the rootdirectory of the drive. Then it will recall
the bad sectors found and adjust the FAT's accordingly.
What is Low/High Level Formatting
A low-level format (first done at the factory)
draws magnetic lines on the hard disk, these days you rarely
need to redo a low-level format.
A high-level format creates a new FAT and
scans the surface of the disk, finding and marking damaged sectors
(those corrupted files). Performing a high-level format is deceptively
easy; simply run the Format utility.
However, the DOS FORMAT program only knows
how to low-level format floppies, not harddrive's, due to the
fact that sector header/trailer information varies widely between
harddrive manufacturers and models. Further, the number of sectors
on a track is fixed for floppies in (DOS floppy formats) but
varies on most harddrive's.
Finally, EIDE harddrive's are preformatted
by the manufacturer typically with dedicated programs that leave
some space on the drive to "remap" bad sectors to,
should they show up over time. This means that if the microcontroller
in the drive detects a bad sector, it will try to reread a number
of times until the checksum matches. Then it will mark that sector
as bad, and store the information in another sector. All this
is invisible from DOS. However, for fast AV or multi-speed CDROM
writers this may mean a hickup in the datastream coming from
the drive, not only when the bad sector is detected, but also
afterwards because the drive will have to get the sector data
from another physical location on the drive involving extra head-seeks.
Therefore, instead of low-level formatting
your EIDE drive when it was trashed, first make sure that there
are no other problems involved (i.e. too fast PIO mode, wd-ctrl
in use for a large incompatible drives, buggy CDROM drivers,
too long (ribbons) between your controller and drives, bad RAM
or bad cache RAM etc).
I strongly advise you
NOT to use the "format" option inside most BIOS's (reachable
from the BIOS setup screen). This FORMAT option was useful for
old MFM and RLL drives, and usually DESTROYS EIDE drives! If
you need to "repair" an EIDE drive (bad sectors, or
"indestructible" viruses etc.) it is best to use a
tool that simply overwrites all sectors. This will force the
drive to "remap" bad sectors itself. Nearly all bad
sectors that are not remapped can be detected by either FORMAT
or SCANDISK (surface scan option) and they will mark the clusters
containing bad sectors as bad in the FAT.