FDISK Guide to Hard Drive Partitioning





FDISK Basics

Let's get started. The first partition of a hard drive is usually a *Primary* partition. It's normally labeled as your C: drive, especially when it's configured as the primary-master. There is normally only *one* Primary partition per hard disk [more are possible with special tricks].

The maximum number of Primary partitions allowed per hard disk is 4. Again, you will normally only have *one* Primary partition per hard disk.

If you have only one hard disk in your system, then you will *need* a Primary partition on that drive.

But if you have more than one hard disk [two, three, four, etc.] in your system, you don't need any Primary partitions on the second, third, fourth (etc.) disks.

  • Extended partitions are required for hard drives with more than one partition. Only *one* Extended partition is allowed per hard disk. You can't do anything with an Extended Partition, without first creating a Logical DOS drive *in* the Extended Partition .. which leads to our next point.

  • Logical DOS drives are created in Extended partitions. They are handy, since you (normally) have only one Primary & one Extended partition per hard disk, giving you the ability to create more than two partitions per hard disk. For example, they would be your D: drive, your E: drive, etc. Each Logical DOS drive gets its own drive letter. You can create more Logical DOS drives on a hard drive than you'll ever need.

For example, you could use FDISK to partition an 80-GB hard drive like so:

  • one 20-GB Primary partition = C: drive
  • one 60-GB Extended partition, containing two 30-GB Logical DOS drives [D + E]. You could also create three 20-GB Logical DOS drives here.

Bootable FDISK Floppy Disk

I posted a Windows ME boot disk on my Downloads page. You can either use this one [labeled "FDISK floppy"], or grab one from bootdisk.com. I suggest the one labeled "Windows ME" as this particular disk contains the latest version of FDISK, which supports hard drives larger than 64-GB.

There's a known-problem with trying to create partitions [with FDISK] larger than 64GB. See here. Microsoft has a file for you to download [if you want to create partitions larger than 64GB]. If you already have a bootable floppy disk that works for you, but merely need the updated version of FDISK for a new hard drive that is larger than 64-GB, you can download the new version of FDISK.exe from my Downloads page.

Download your bootdisk of choice and put a brand new, formatted floppy into your A: [floppy-disk] drive. Extract the contents of the self-extracting executable file to the floppy. Leave the boot floppy in the A:/floppy drive and reboot. At the command prompt [A:\>], type "FDISK" (without the quotes) and hit the <Enter> key. Here we go.

The program will ask if you want Large Disc Support. Answer: 'Yes' by pressing the <Enter> key when the letter 'Y' is selected/highlighted. "Large disc support" provides support for FAT32 [and NTFS], which allows you to create partitions larger than 2GB. If you answer 'No,' you would get FAT16, which limits your partitions to 2GB each [this would be bad, especially if you have a large hard disk].





Initial FDISK Screen

The initial FDISK screen looks like this:

  1. Create DOS partition or Logical DOS Drive
  2. Set active partition [Your C: drive is usually your active partition]
  3. Delete Partitions or Logical DOS Drive {Brand new drives won't have any partitions to delete]
  4. Display partition information [Use this option to verify your work]
  5. Change current fixed drive [For systems with more than one HDD]

Hopefully you've already backed up any data, if the drive is not brand new. Repartitioning will cause you to lose any data contained on the repartitioned drive(s). If you have four IDE/ATA hard disks in your system, FDISK will report them in the following order:

  • Disk drive 1 = Primary-Master
  • Disk drive 2 = Primary-Slave
  • Disk drive 3 = Secondary-Master
  • Disk drive 4 = Secondary-Slave

If your system contains no primary-slave nor secondary-master as a fixed disk drive, then your secondary-slave would be reported as: Current fixed disk drive: 2.

Assuming the drive is not new, we first need to remove existing partitions. Select item #3. [If you have a brand new hard drive, you won't have any partitions to delete.] Note: If you have more than one hard drive in your system, you will first have to select item #5: Change current fixed drive, to access the desired drive.

Caution: If you have more than one physical hard drive, you need to be absolutely certain the drive you *think* you're working with is indeed that one. I cannot stress this strongly enough. If you partition or format the wrong drive, you will cry. At the top of this window, FDISK will display the Current fixed disk drive. This is the drive you're working on/with.

Some people disconnect all other hard drives before partitioning and formatting. I don't feel this is necessary, and that a little caution should suffice. But it's not a bad idea, especially for FDISK noobies, or if you're unsure about which drive you're working with.

The FDISK Delete Screen

The delete screen in FDISK looks like this:

  1. Delete Primary DOS Partition [Delete this partition last]
  2. Delete Extended DOS Partition [Delete this partition next]
  3. Delete Logical DOS Drive(s) in the Extended DOS Partition [Delete these first]
  4. Delete Non-DOS Partition [These can be difficult to delete with FDISK]

Always delete partitions in the *reverse* order you create them. In other words, always delete partitions like so: First delete all Logical DOS drives [highest drive letter first]. Next delete the Extended partition. Lastly delete the Primary partition.

Eric from New York City wrote to say he encountered a problem with a Windows 98 start-up disk. It gives him the error: NTLDR is missing. Press any key to restart. Pressing the proverbial "any key" does no damn good.

The Windows Me boot disk from bootdisk.com allowed him to load DOS and access FDISK. But FDISK could not delete his NTFS partition. A utility called delpart.exe was required. You can download delpart.exe from either my Binaries page, or from the utilities page at bootdisk.com [listed near the bottom, scroll down to heading labeled "Partitioning"].

It's 123KB. Copy it to your boot floppy and execute it from there. Delete NTFS partitions as desired. Then reboot and create partitions with FDISK. So the combo that works to delete NTFS partitions is: delpart.exe on a WinMe boot floppy.

Deleting Hard Drive Partitions

FDISK has trouble deleting non-DOS partitions. This section has grown so large that I've given it its own page. If you're having trouble deleting partitions for any reason, see here: [Problems deleting Partitions].

After all partitions have been removed/deleted, return to the first screen [ESC]. Now we'll create our new partitions. Select item #1: Create DOS partition or Logical DOS Drive.

The FDISK Create Screen

The Create Screen looks like this:

  1. Create Primary DOS Partition [Create this first]
  2. Create Extended DOS Partition [Create next, use *all* remaining space]
  3. Create Logical DOS Drive(s) in the Extended DOS Partition [Create last]

Create partitions in the following order: First > Primary. Second > Extended. Lastly > Logical DOS Drives [in the Extended partition].

Note: you don't necessarily have to create a Primary partition. Your drive will work fine with no Primary partitions, long as it's not the only hard drive in your system. You need only one Primary partition per system. All other drives can be comprised entirely of Logical DOS drives in Extended partitions. With that said, each hard drive normally has one Primary partition.

Creating a Primary partition can change your drive-letter designation configuration on pre-existing hard drives, which can generate problems. If your system thinks a certain file is located on a certain drive letter [say for example: D, and your D drive changes to E], and that drive letter changes, your system won't be able to locate that file.

This can cause problems. I'll discuss problems associated with drive-letter changes later, and give you ways to solve the issues. Refer to the section below [next page] labeled "Drive Letters" for more info along these lines.

Now we're going to create a Primary partition. If asked to use *all* space, answer 'No' and enter the amount you wish for the C: drive [or whatever drive it will be] .. unless you want only a single-partition hard drive. In which case, you would answer 'Yes'.

The first partition on your first hard drive should automatically be set to Active partition. If not, FDISK may ask you, or you may have to select item 2: Set active partition from the main menu. The active partition is usually the C: drive. Even if you don't install your operating system to your C: drive, your O/S will still install key boot files [such as boot.ini] to your active partition.

While it is possible to have up to 4 Primary partitions per hard disk, only one can be active at any one time. You can change which partition is active, altho you will probably never need to do this.

Note: FDISK has a problem displaying information for hard drives that exceed 100-GB. The extra character causes the size value to wrap to the next line. Once you realize what is happening, it's not difficult to interpret the data. But it can be confusing and takes a little extra care. The program still works fine, tho.

When entering data for partition sizes, you can enter either absolute values [in MB, 30000 MB = 30-GB], or you can enter percent values [25% of a 120-GB hard drive = 30-GB]. FDISK will not allow you to enter a value greater than 99999 MB [99-GB]. You would have to use a percent value in this case. This is no problem. You need to include the "%" character.

Extended Partitions

Next we create the Extended partition. Recall that each hard drive can only have one Extended partition. Use *all* remaining space. Repeat, use all remaining space to create your Extended partition. If you don't, you'll wind up with unused space on your hard drive [a common noobie problem]. For more info along these lines, refer to the section below [next page] labeled "Two Common Problems".

FDISK should automatically advance to the next step -> creating Logical DOS drives. It should give you a message that says (something like), This drive has no Logical DOS drives. Would you like to create some now? Enter the amount for the size you want to make the first Logical DOS drive/partition.

If you only have one hard disk in your system, this will be your D_drive. If you only want two partitions on this drive [one primary and one logical DOS drive], then you would enter all remaining space contianed in the Extended partition for the size of this logical DOS drive.

After you create the first Logical DOS drive, enter the remaining space for the third partition .. or make it however big you want, and add however many Logical DOS drives you'd like. Now we're finished with FDISK, so exit out.