www.bootdisk.com reviewed and fixed a typo on February 26, 2016 and I still enjoy the read Using the fdisk utility to set up hard drives It's one of the more difficult utilities to explain and learn how to use especially if you need to delete partitions with it. The basic problem is learning what the terms mean, for example, Primary partition, Extended partition, Logical drive, Active partition. But once you learn and understand what the terms are you can use ANY partition program. So, I wrote this analogy which I believe explains things quite well, so even a beginner can understand what a partition is and how to use fdisk or other programs that deal with setting up your hard drive. Let's begin: Suppose you just bought a 100 by 100 foot lot for your retirement home in Florida. The developer put a road through an old sod farm and put up a sign for the lot you bought called Lot B. You go to see your lot and all you see is the sign next to the road and a large field of grass. If you take a closer look, you can see the steel pipes or wooden property markers that the surveyors used to define your lot. This is analogous to what your hard drive looks like when you buy it new or have deleted all the partitions. The X's would be the property markers. Exibit A. New hard drive / aka Lot B X X No partitions - No Drive letters X X A computer needs to put data on the hard drive, but is not smart enough to find the property markers. An analogy would be you need to have the lumber yard deliver some wood for your new home. The delivery guy finds the Lot B sign but only sees the old sod field and doesn't know exactly where to drop the load. So the first step is to fence it in to make it clear to your computer and the delivery guy where exactly the data or load of wood is supposed to go. This is called creating the Primary partition. A Primary partition may be sized for the entire size of your drive or just a portion of it. When you run fdisk, the first screen will ask: Do you wish to Enable large disk support? Choose Y if you will be installing Windows 95B or higher. Then select menu item 1, Create DOS partition or logical DOS drive On the next screen select item 1 again, Create Primary DOS Partition And just follow the prompts. Let's say you create a Primary partition using all the space on the drive. If you do your hard drive or Lot B will now look like this: Exibit B. Hard drive with 1 Primary partition / aka Lot B X X ################################################## # # # # # # # 1 Primary partition called Drive C: # # # # # # # # # # # # # # # ################################################## X X Notice how you lost some of the capacity of the drive. The same thing happens when you put up a fence as you have to dig the post holes and run the fence WITHIN the boundries of your property. For example, if you bought a 100 gig drive you now only have 95 gigs to work with. In order to boot from this drive the Primary partition NOW has to be set Active. During the fdisk process it "should" automatically remind you to do this. If it doesn't one can always choose to set Active by running fdisk again and selecting that option on the fdisk menu. So, setting the Primary partition Active only means that you are setting it up so it can be used to start up your computer. The only partition you need to be set Active is the Primary partition on your first physical hard drive. Yes there are exceptions to this for more advanced users who want to boot from their second or third physical hard drive. In any case your drive can now be formatted after you reboot. Let's review: Primary Partition - The first section on the hard drive Set Active - Letting your computer know it can use the drive to startup What is an Extended Partition? As mentioned earlier, you can choose the size of your Primary partition. Exibit B shows that the owner of the Lot or Drive only wants a single fence or Drive letter. But what if you want to divide your hard drive or property into 2 sections so you will have 2 drive letters for the same physical hard drive? Perhaps fence in a spot for your mother-in-law's trailer when she comes to visit or create a space for your mp3 file collection. This is called creating an Extended partition. In order to do so you first have to create a smaller Primary partition, perhaps using 33% of the drive. fdisk will prompt you on how large you want to make the Primary partition. When you see the question: "Do you wish to use the maximum available size for a Primary DOS Partition and make the partition active?" Answer N and then put in the % you want to use. In this example we are using 33%. Follow the prompts then reboot. Restart and run fdisk again, choose menu item 1 again, but this time choose menu item 2 on the next screen, Create Extended DOS partition. You will be prompted to Enter partition size in Mbytes or percent disk space (%). Hit Enter and it will say "Extended DOS Partition created. Hit Escape and it will say "No logical drives defined" Hit Enter then Escape, Escape, then reboot for it to take effect. A hard drive with a Primary partition that only uses 1/3 of the drives capacity and an Extended partition that uses 2/3 of the drive would look like this: Exibit C. Hard drive with 1 small Primary and 1 large Extended partition X X ################################################## # # # # # # # 1 Primary # # # partition # Extended partition # # called # No drive letter # # Drive C: # # # # # # # # # # # # # # # # # ################################################## X X OK that was a lot of information all at once as creating the Extended partition and then creating the Logical drive within it all happens at the same time. To summarize graphically: Exhibit C above shows what happened when you created the Extended partition, or put up a fence dividing your property. Exhibit D below shows what happened when you created the Logical drive, which in this example puts up a SECOND fence so there is no confusion where the boundries are. Exibit D. Hard drive with 1 small Primary and 1 large Extended partition with 1 Logical drive X X ################################################## # #LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL# # #L L# # 1 Primary #L L# # partition #L Extended partition with 1 L# # called #L Logical Drive D: L# # Drive C: #L L# # #L L# # #L L# # #L L# # #L L# # #LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL# ################################################## X X Now your hard drive has been divided into 2 usable parts, the first bootable section is called Drive C: and the second part is called Drive D:. Drive D: can now be formatted. Let's review: Extended Partition - Telling your computer you plan on using the remaining capacity of the hard drive for data storage after you've allocated space for the Primary partition Logical Drive - Going through with the plan and informing your computer to to assign a drive letter to the remaining space on your hard drive If you want to divide your drive into MORE THAN 2 drive letters, after you create an Extended partition and go to create the Logical Drives you will have a choice to divide the Extended partition into 2 or more Logical drives if you want. This has to be done, however, when you first define the Logical partitions or later on if you select item 3, Create Logical DOS drive(s) in the Extended DOS partition using fdisk. Note that if you have 2 hard drives in your computer the Primary drives are assigned drive letters first. For example, suppose you partition your new drive you want to boot from into 2 parts, one Primary and one Logical. The computer will assign Drive letter C: to the first Primary partition it sees, and then assign Drive letter D: to the second Primary partition it sees which may be your second hard drive. The Logical drive you created on your new hard drive would be assigned Drive E: Note that XP can bend many of these "rules" however using Disk Management. Why should I consider creating more than one partition? To make your life less complicated and/or if you are only going to install one operating system on then personally, I'd stick to one partition so you will only have 1 hard drive letter to manage. On the other hand here are 2 common reasons for dividing your hard drive into 2 parts. Reason #1. You want Windows 9X on the first partition and Windows XP on the second partition. This will automatically give you a dual boot system but you have to install Windows 9X first and tell XP during the install to install to drive D:. Reason #2. You want to save time defragging your hard drive and/or running certain applications like anti-virus, etc. Install XP on the first partition and use the second for your huge data files like mp3s, videos, etc. This way you can just select the "working files" on drive C: to defrag or scan to save lots of time. NOTE - The biggest mistake people make when dividing their drive into 2 or more sections is that they dont make the first section, aka the Primary partition, aka Drive C:, large enough. Removing partitions To remove partitions and logical DOS drives essentially you remove them in the reverse order they were created if using fdisk. ie remove Logical drives first, then remove Extended partition, them remove Primary partition. ############################################## Ed Jablonowski