PARTITIONING
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What Is Partitioning?
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How Many Partitions Do You Need?
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NON-DOS Partitions
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FDISK
Screens
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Running FDISK
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Opening
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The Main Menu Screen choices
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Options
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Setting or checking the Active Partition
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Set Active Partition
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Changing the drive to be worked on.
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Change Current Fixed Disk Drive
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Checking your current Partition Settings
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Display Partition Information
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Deleting Partitions
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Delete Partition or Logical DOS Drive
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Creating a DOS partition
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Create DOS Partition or Logical Drive
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Creating an Extended Partition
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Create Extended DOS Partition
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Creating Logical Drives
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Create Logical Drive(s) in the Extended DOS partition
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Command Options - FDISK /MBR /STATUS
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Links to other informative sites
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What Is
Partitioning?
Partitioning puts barriers on a
disk so different areas of the drive can have different
types of data on them. The reasons for partitioning may be
for running different operating systems on the same drive,
Microsoft DOS, LINUX and IBM Warp to name a few. There can
be further subdivisions in each partition for other reasons.
Other reasons I have used
Partitions are:
1. LIMITING LOSES. If a file corrupts a drive the damage is
limited to that drive.
2. PROTECTING FROM HARD DISK FAILURES. I have a drive that
developed a physical surface defect. I created three
partitions using only the partitions in the good area. This
drive still works after 3 years, but was unusable before
partitioning.
3. SPACE EFFICIENCY. With FAT16 partitions the space is
divided into a limited number of sectors. The bigger the
drive, the bigger the sector size. Any file, no matter how
small, uses the sector size as the minimum space it
requires. Four files with 1 byte each can use more that 100
kb with 32 kb sector sizes. A 1 gigabyte partition will have
16kb sectors.
FAT32 uses a constant 4096 sector size (up to 8gb). However,
smaller sectors can slow the drive and some programs are not
compatible with FAT32.
4. FOOLING AROUND. I can backup all the files from one drive
to another, format the drive, then restore the files. I can
use test installations that mirror another drive.
Prior to Windows 95b
(OSR2) the largest drive the Microsoft operating system
could read was 2.1 gigabytes. So a 5.0 gb drive would only
show as a 2.1 gb drive. By dividing it up you could have
five one gigabyte drives. With this, DOS could use your
whole drive. With different partition options you get a
variety of results. If each partition is a primary partition
the drive letter won't shift if you add another hard disk.
There is a limit to how many of these can exist on a single
drive. By creating an Extended partition you can divide it
up using all the letters in the alphabet. These are FAT or
FAT16 partitions. As the partition gets smaller so does the
sector size, which can improve the efficiency of the disk
usage.
With Windows 95b and
later you can use FAT32 partitions which keep the block size
at 4096 on partitions up to 8.4gb in size. That doubles to
8048kb on partitions over 8.4gb and less than 32gb. It has a
maximum size ot 2 terabytes. But there are drawbacks. Only
the later systems can read the drive. You can't use DOS 6.22
or, even, Windows 95a to access the drive. If you wanted to
install Windows 3.1 on the drive you can't.
A freeware alternative to
FDISK is
Ranish Partition Manager. This, like Symantec's
Partition Magic, can adjust and reconfigure partitions
without losing data.
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Running
The FDISK Utility
To run FDISK, type FDISK at
the DOS Prompt. You should do this from a floppy disk if you
are changing partitions as the computer may lose its boot
files. The file FDISK.EXE must either be in the directory
you are in when you type it or in PATH. If it is in a
different directory, you must type the full path to it.
When you start FDISK,
it tests to see what hard drive information it can find. If
you have Windows 95b or later and you have a hard disk
larger than 512 mb, the following screen will come up. If it
is FDISK from Windows 95a or DOS or the drive is not over
512 mb in size, the MAIN Screen will come up.
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Your computer has a disk larger than 512 MB. This version of
Windows
includes improved support for large disks, resulting in more
efficient
use of disk space on large drives, and allowing disks over 2
GB to be
formatted as a single drive.
IMPORTANT: If you enable large disk support and create any
new drives on this
disk, you will not be able to access the new drive(s) using
other operating
systems, including some versions of Windows 95 and Windows
NT, as well as
earlier versions of Windows and MS-DOS. In addition, disk
utilities that
were not designed explicitly for the FAT32 file system will
not be able
to work with this disk. If you need to access this disk with
other operating
systems or older disk utilities, do not enable large drive
support.
Do you wish to enable large disk support (Y/N)...........?
[N]
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The FDISK Main Menu.
In Windows 95a
and DOS versions, this is the first screen you will see. Here you choose
what function you will use. You can view information without changing
anything, delete a partition, create a new partition or set an existing
partition as active. Use caution as you use ESC to exit the program.
This does not undo changes you make.
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Checking your current
settings with FDISK
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Start FDISK. If you are
running Windows 95b or later you will get the
Large Disk Support?? screen. Answer Y unless you know
that the partition is not set as "Large".
The next screen will be the
FDISK Main Menu Screen. If you have more than one
physical drive, there will be 5 options. If this is the
case, select
option 5 to select which drive you are checking. When
you have selected, you will go to the next step.
If you only have a single
drive, there will only be 4 choices. Select
choice 4. This screen will display Primary and Extended
partition information.
If you have an Extended
Partition, then there are most likely Logical Drives
defined. If you opt to see Logical Drive information, a
screen showing that will be called up.
The total space used by all
of the logical drives should total 100%. This is only 100%
of the Extended partition, not 100% of the Drive's space.
You may have a single
partition using 100% of the disk space if the drive is 8.4gb
or less with "LBA" enabled in the BIOS Setup. FDISK must
also have "Large Disk Support" on for this size to be used.
If the BIOS has a "NORMAL"
setting for this drive, the maximum size will be 512mb.
If you have an extended
partition, the Primary Partition will be less than 100%.
NON-DOS partitions will also subtract from that available
for the Primary Partition. Some OEM computers have a small
NON-DOS Partition. Other operating systems such as Linux or
Windows NT will register as NON-DOS partitions.
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Display
Partition Information
Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes
System Usage
1 Non-DOS
8 %
C: 2 A PRI DOS DRV_PART_A 1020
FAT16 25%
3 EXT DOS 4080
75%
Total disk space is 4103 Mbytes (1 Mbyte = 1048576
bytes)
The Extended DOS Partition contains Logical DOS Drives.
Do you want to display the logical drive information
(Y/N)......?[Y]
Press Esc to return to
FDISK Options
The drive the computer boots from (normally C
drive and the first DOS partition of the First
physical drive) must have an A in front of it in
the Status column. Without this, the computer
will not try to boot from the drive. There can
only be one "Active Partition" on a physical
drive. FDISK cannot set 2 Active Partitions.
However, a drive set as "active" then added may
also be marked active.
If you have an extended DOS partition, press Y
and enter to see how it is divided up.
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Active Partition
In order to be bootable, a
partition must be set as Active. Microsoft FDISK can only set one
partition as active at a time. If a drive is set as active and is teamed
with another drive that is also set as active, the first disk will be
the boot drive. If the first drive is turned off on the BIOS, the second
drive can often be booted from without other alterations. Third party
Programs, such as Partition Magic, can set more than one partition as
active at the same time.
To check the setting or change
which drive is set to active, select:
2. Set active partition
from the Main FDISK Menu. The active partiton should have an A in the
Status column. to change the active partition, type the number of the
partition you want to use at the end of the line near the bottom of the
screen.
Only Primary partitions can be
set as active. Extended partitions cannot be set as active.
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Set Active Partition
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Current fixed drive drive: 1
Partition Status Type Volume Label Mbytes
System Usage
1 Non-DOS
8 %
C: 2 A PRI DOS DRV_PART_A 1020
FAT16 25%
3 EXT DOS
4080 75%
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This shows all of the drive usage. If you have a
single partition, you will only see one.
If you have more tha one active Partition, you
can change which partition is used to boot from.
If you have other operating systems (Linux, OS2,
etc) you can set which one the computer will
run.
If a primary partition is set as Active, you
will see an A under Status. Only an active
partition can be bootable.
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Total disk space is 5100 Mbytes (1 Mbyte =
1048576 bytes)
Enter the number of the partition you want to
make active...........: [ ]
Press Esc to return to
FDISK Options
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Deleting Partitions
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Start FDISK. If you are
running Windows 95b or later you will get the
Large Disk Support?? screen. Answer Y unless you know
that the partition is not set as "Large".
The next screen will be the
FDISK Main Menu Screen. If you have more than one
physical drive, there will be 5 options. If this is the
case, select
option 5 to select which drive you are checking. When
you have selected, you will go to the next step.
If there are more than just
a single partition, they must be deleted in a sequence.
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Logical Drives must be deleted before Extended Partitions.
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Extended Partitions must be deleted before a Primary DOS
partition can be deleted.
You can delete Logical
Drives without affecting other partitions. You can delete an
Extended partition without affecting the data on a Primary
partition.
From the
FDISK MAIN Menu select:
3. Delete partition or Logical DOS Drive
If you have a non-DOS
partition that you can't remove such as a Linux Partition
see:
MS-DOS Partition Removal Debug Script From Win Drivers
Com's Hard Drive Center.
Another program you can use
is the ZAPART Utility. Find it on
Micro Firmware Technical Support. This DOS utility can
be used to erase the boot sector on a hard drive. This can
be useful for removing drive overlay programs such as Disk
Manager or EZ-Drive or for removing otherwise "confused"
partitions that FDISK will not remove.
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Delete Primary DOS Partition
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Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes
System Usage
1 Non-DOS
8 %
C: 2 A PRI DOS DRV_PART_A 1020
FAT16 25%
3 EXT DOS
4080 75%
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This shows all of the drive usage. If you have a
single partition, you will only see one.
To delete a Primary DOS partition you must enter
its number. You will then be asked to enter the
Volume Label to verify.
If an extended partition exists, you will not be
able to delete it until they are deleted.
If a primary partition is set as Active, you
will see an A under Status. Only an active
partition can be bootable.
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Total Disk Space is 5100 Mbytes (1 MByte =
1048576 bytes)
WARNING! Data in a deleted DOS Drive will be
lost.
What drive do you want to
delete...............................? [ ]
Press Esc to return to
FDISK Options
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Delete Extended DOS Partition
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Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes
System Usage
1 Non-DOS
8 %
C: 2 A PRI DOS DRV_PART_A 1020
FAT16 25%
3 EXT DOS
4080 75%
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This shows all of the drive usage. If you have a
single partition, you will only see one.
If the extended partition has logical drives in
it, you will not be able to delete it until they
are deleted.
If a primary partition is set as Active, you
will see an A under Status. Only an active
partition can be bootable.
To delete a partition you must enter its number.
You will then be asked to verify.
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Total Extended DOS Partition size is 4080 Mbytes
(1 MByte = 1048576 bytes)
WARNING! Data in a deleted Logical DOS Drive
will be lost.
What drive do you want to
delete...............................? [ ]
Press Esc to return to
FDISK Options
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Delete Logical DOS Drive(s) in the Extended DOS
Partition
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Drv Volume Label Mbytes System Usage
D: DRV_PART_B 1020 FAT16 25%
E: DRV_PART_C 1020 FAT16 25%
F: DRV_PART_D 1020 FAT16 25%
G: DRV_PART_E 1020 FAT16 25%
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If you had a 5gb drive partitioned 5 ways, this
is how the extended partition would look.
The percentages and megabytes used are only for
the extended partition. Drive C and the bytes
used in the primary DOS partition are not
included here.
When you type Y to delete a partition, you will
be prompted to enter the Volume label exactly.
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Total Extended DOS Partition size is 4080 Mbytes
(1 MByte = 1048576 bytes)
WARNING! Data in a deleted Logical DOS Drive
will be lost.
What drive do you want to
delete...............................? [ ]
Press Esc to return to
FDISK Options
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Creating DOS Partitions
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Start FDISK. If you are
running Windows 95b or later you will get the
Large Disk Support?? screen. Answer Y unless you know
that the partition is not set as "Large".
The next screen will be the
FDISK Main Menu Screen. If you have more than one
physical drive, there will be 5 options. If this is the
case, select
option 5 to select which drive you are checking. When
you have selected, you will go to the next step.
If a drive already has
partitions on it:
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There must be some unused space available for the partition.
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There must not be another DOS Partition already. You can
create multiple Primary DOS Partitions with Aftermarket
programs such as Partition Magic or
Ranish Partition Manager
If you want more than one
Drive defined, do not use all of the available space for the
Primary Partition.
From the
FDISK MAIN Menu select:
1. Create DOS partition or Logical DOS Drive
On that menu select:
1. Create Primary DOS Partition
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If no partition yet exists on the drive
you will get the following screen:
Create
Primary DOS Partition
Current fixed disk drive: 1
Do you wish to use the maximum available size for a Primary
DOS Partition
and make the partition active
(Y/N)............................? [Y]
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If there are no partitions already set, you will
get this screen. If there are already partitions
on the drive, you will get
the add partition
screen instead.
If you answer "Y" that you want to use all of
the disk space for this partition, you will be
prompted to Press ESC and the computer will
reboot. You will still need the boot disk as the
drive is yet to be formatted. You will have no
other option when you select "Y". If you enter
"N", the
next menu
will be called up.
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Press Esc to return to
FDISK
Options
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Create
Primary DOS Partition
Current fixed disk drive: 1
Total disk space is 5000 Mbytes (1 Mbyte = 1048576 bytes)
Maximum space available for partition is 5000 Mbytes (100%)
Enter partition size in Mbytes or percent of disk space (%)
to
create a Primary DOS
partition..............................[ 100%]
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This screen is called up if you choose not to
use all of the available space for a Primary DOS
Partition.
Enter either the Megabytes or enter a percentage
including the percent sign. When you press enter
it will show
a screen
displaying the resulting partitions.
You may back out by pressing ESC.
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Press Esc to return to
FDISK Options
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Create
Primary DOS Partition
Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes
System Usage
C: 1 PRI DOS 5000
UNKNOWN 100%
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This screen is called up after you create a new
partition. Note that the partition is not
automatically set as active. There is also no
Label yet. And because the drive is not
formatted yet, the system is UNKNOWN.
Pressing ESC returns you to the FDISK options.
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Press Esc to return to
FDISK Options
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If a partition already exists the
screen will show the useage and what space is available for a Primary
Partition.
Create
Primary DOS Partition
Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes System Usage
1 Non-DOS 8 %
C: 2 A PRI
DOS WD43_A 1020 FAT16 25%
3 EXT DOS
4080 75%
Primary DOS Partition already exists.
Press Esc to continue
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When you select "Create primary DOS
partition" you can enter the size as a percentage of the total undefined
space or you can enter the size in Megabytes. If you want 4 equal drives
you could specify 25%.
Next you create a Extended DOS
partition. This would use all remaining space unless you have other type
of partitions to define.
Now you can define logical drives
which use the Extended partition. Now you have to be a mathematician as
the numbers change. You used 25% for the first drive. Now you have 75%
left to split three ways. You will use 33% for the next drive. That
leaves you with two to divide 2 ways. 50-50 split, easy. Now the hardest
is the last one. Just use what's left. Now, exit the program and restart
the computer. You will now have to format any drives you just created.
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Creating Extended
Partitions
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Start FDISK. If you are
running Windows 95b or later you will get the Large Disk
Support?? screen. Answer Y unless you know that the
partition is not set as "Large".
The next screen will be the
FDISK Main Menu Screen. If you have more than one physical
drive, there will be 5 options. If this is the case, select
option 5 to select which drive you are checking. When you
have selected, you will go to the next step.
You can define a drive with
only Extended Partitions. You cannot, however, boot from it.
From the FDISK MAIN Menu select:
1. Create DOS partition or Logical DOS Drive
On that menu select:
2. Create Extended DOS Partition
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Create
Extended DOS Partition
Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes
System Usage
C: 1 PRI DOS 5000
UNKNOWN 100%
Total disk space is 5000 Mbytes (1 Mbyte = 1048576
bytes)
Maximum space available for partition is 4000
Mbytes (80%)
Enter partiton size in bytes or percent of disk space (%) to
create an extended DOS
Partition.............................[ 4000]
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You must have unused space for the partition.
Usually you would specify all remaining space
for the Extended Partition. The available space
is automatically entered.
Enter a number or a percentage (with the percent
sign) if you want to use less. You might do this
if you plan to have a non-DOS partition.
Press Enter and the changes will be enter and
you will be taken to
another screen
that will show the new useage.
Pressing ESC returns you to the FDISK options
without changes.
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Press Esc to return to
FDISK Options
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Create
Primary DOS Partition
Current fixed disk drive: 1
Partition Status Type Volume Label Mbytes
System Usage
C: 1 PRI DOS 5000
UNKNOWN 20%
2 EXT DOS 4000
UNKNOWN 80%
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This screen is called up after you create an
Extended partition. Note There is no Label yet.
And because no drives are not set up yet in the
extended partition, the system is UNKNOWN.
Pressing ESC returns you to the FDISK options.
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Press Esc to return to
FDISK Options
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Creating Logical Drives
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Start FDISK. If you are
running Windows 95b or later you will get the Large Disk
Support?? screen. Answer Y unless you know that the
partition is not set as "Large" (FAT32).
The next screen will be the
FDISK Main Menu Screen. If you have more than one physical
drive, there will be 5 options. If this is the case, select
option 5 to select which drive you are checking. When you
have selected, you will go to the next step.
You must have an Extended
Partition already created. Logical Drives can only be
created in an Extended Partition.
From the FDISK MAIN Menu select:
1. Create DOS partition or Logical DOS Drive
On that menu select:
3. Create Logical DOS Drive(s) in the Extended DOS Partition
You can divide that space up until there is none left.
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Create
Logical drive(s) in the Extended DOS Partition
Current fixed disk drive: 1
No logical drives defined
Total
Extended DOS partition size is 4000 Mbytes (1 Mbyte =
1048576 bytes)
Maximum space available for partition is 4000 Mbytes
(100%)
Enter logical
drive size in bytes or percent of disk space (%) to use...[
4000]
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You must have an Extended DOS partition created
before you can use this function. You could
specify all remaining space for the Extended
Partition. Or you can divide it up. You can have
as many as 23 logical drives, if you want. Of
course there will be no drive letter left for
anything else, such as CDROM drives.
The available space is automatically entered.
Enter a number or a percentage (with the percent
sign) if you want to use less. Keep creating
drives until all of the space is used up. You
will keep returning to this screen after each
entry.
Press Enter and the changes will be enter and
you will be taken to
another screen
that will show the new useage.
Pressing ESC returns you to the FDISK options
without changes.
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Press Esc to return to
FDISK Options
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Selecting the Drive
to work with.
If you have more than one physical drive installed on the computer, this
menu item will be added to the Main Menu. The choices to Delete and
Create partitions are all this menu affects. And the those changes only
affect the selected drive.
The screen displays the current
drives so you can see any available unused drive space.
Change
Current Fixed Disk Drive
Disk Drv Mbytes Free Usage
1 5080 100%
C: 1020
E: 1020
F: 1020
G: 1020
2 515 100%
D: 515
The physical drive(s) are listed in the disk
column. The letter assigned to each partition is
listed in the "DRV" column. The first DOS
partition of each physical drive uses the first
hard drive letters. That means the letter for
the first drive in the extended partition of
disk 1 will be the first letter after the first
DOS partition of the second drive. Note that
Disk 2 is drive D. The first drive jumps from C
to E if there is a second drive. That cannot be
changed using FDISK. Keep that in mind as
programs installed to D drive may no longer be
on D drive after a drive is added.
Enter the number of the drive you want to work
with.
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(1 MByte = 1048576 bytes)
Enter Fixed Disk Drive Number
(1-2).......................[1]
Press Esc to return to
FDISK Options
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NON-DOS Partitions
As mentioned at the start, other operating systems can exist
on the same hard drive. Among these are LINUX and IBM Warp.
These will generally be reported as NON-DOS Partitions. DOS
FDISK will probably not be able to do anything with them.
They must be handled by the programs that created them.
Another type of NON-DOS Partition is the OEM operating
system. Compaq and others use this.
DO NOT DELETE THIS!
On Compaq, this partition contains some of the BIOS
information. If this partition is deleted, you may not be
able to get into the BIOS Setup Utility. And, of course,
nothing will probably work. You can download a utility that
should restore this from Compaq. You may also find this
Utility on the Quick Restore CD in a directory named
F10Setup.
See
Deleting Partitions for
methods of deleting NON DOS Partitions.
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FDISK
/OPTIONS
You can check the partition
Drive letters by typing:
FDISK /STATUS
at the command line. It will display all physical Hard
drives, their partitions, usage and drive letter assignment.
You can use this command at REAL DOS Mode or in a DOS
window. It does not run the FDISK Utility. This can be
useful when you want to know what drives are available and
how much space is on each. This allows you to compare them
all on one screen.
FDISK /MBR
This command (which is not listed by command help) erases
part of the Master Boot Record of the first hard drive. You
will get no response when you use it which may let you think
it did nothing. It can be useful for clearing defective
information that may have been written by a virus. However,
it can also erase wanted information that may be needed.
See:
FDISK /MBR Rewrites the Master
Boot Record, a Microsoft Knowledgebase Article for
more.
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How Many Partitions Do You Need?
With DOS versions and Windows 95a, a single partition could
only be up to 2.1gb. Smaller partition sizes created smaller
cluster sizes which could improve disk capacity
substantially, depending on the size of files stored there.
With FAT32 partitions, the cluster size remains a constant
4048 bytes with partitions sizes of 8.4gb and less. If you
are using a FAT32 partition, you may want to have a single
large drive. However, if you have a drive larger than 8.4gb,
it might be more efficient to divide the drive into multiple
partitions. Also, you can have one or more of the partitions
set as a FAT16, which will be compatible with older programs
such as DOS and Windows 3.1, as well as Drivespace or
Doublespace compression.
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