PARTITIONING

PARTITIONING

Checking your current Partition Settings	Creating an Extended Partition
Deleting Partitions	Creating Logical Drives
Create a DOS partition	NON-DOS Partitions
Setting or checking the Active Partition	Links to other informative sites

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.

Checking your current settings with FDISK

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.

Deleting Partitions

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".

If there are more than just a single partition, they must be deleted in a sequence.

Logical Drives must be deleted before Extended Partitions.

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.

Creating DOS Partitions

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".

If a drive already has partitions on it:

There must be some unused space available for the partition.

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

Creating Extended Partitions

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".

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

Creating Logical Drives

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".

You must have an Extended Partition already created.
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.

When you start FDISK, it tests to see what you have. If you have Windows 95b or later and you have a hard disk larger than 512 mb, this screen will come up.

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]

The FDISK Main Menu.

Microsoft Windows 95
Fixed Disk Setup Program
(C)Copyright Microsoft Corp. 1983 - 1995

FDISK Options

Current fixed disk drive: 1

Choose one of the following:

1. Create DOS partition or Logical DOS Drive
2. Set active partition
3. Delete partition or Logical DOS Drive
4. Display partition information
5. Change current fixed disk drive

Enter choice: [1]

Press Esc to exit FDISK

If you have only one physical Hard drive, the 5th choice on this menu will not be there.

Click on a line to see what will be on the screen it calls up.

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.

    (1 MByte = 1048576 bytes)
    Enter Fixed Disk Drive Number (1-2).......................[1]


    Press Esc to return to FDISK Options

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.

Delete DOS Partition or Logical DOS Drive

Current fixed disk drive: 1

Choose one of the following:

1. Delete Primary DOS Partition
2. Delete Extended DOS Partition
3. Delete Logical DOS Drive(s) in the Extended DOS Partition
4. Delete Non-DOS Partition

Enter choice: [ ]

Press Esc to return to FDISK Options

This is the delete menu.

If there are Logical drives set up they must be deleted first.

Next is the extended partition if one exists.

Finally, you can delete the primary DOS partition and any other partitions you want.

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.

Set Active Partition
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%
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.
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

Delete 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 DRV_PART_A 1020 FAT16 25% 3 EXT DOS 4080 75%
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.
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

Delete Extended DOS Partition
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%
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.
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

Delete Logical DOS Drive(s) in the Extended DOS Partition
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%	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.
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

Go back to the Main menu and select 1. Create DOS partition or Logical DOS Drive.

Create DOS Partition or Logical DOS Drive

Current fixed disk drive: 1

Choose one of the following:

1. Create Primary DOS Partition
2. Create Extended DOS Partition
3. Create Logical DOS Drive(s) in the Extended DOS Partition

Enter choice: [1]

Press Esc to return to FDISK Options

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

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.

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 also:
How to FDISK a Hard Drive from Murf's Garage (Murf's new Site)
For a Free Partition utility:
Ranish Partition Manager

Other Links:
Partition Definition from Internet.com's Webopedia
How to Use the Fdisk Tool from the Microsoft Knowledgebase Articles

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Updated August 17, 2002