Considerations when planning disk partitions

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Considerations when planning disk partitions

You must plan your disk partitions before you run Setup only if both of the following conditions are true:

  • You are performing a new installation, not an upgrade.

  • The disk on which you are installing is a basic disk, not a dynamic disk. Basic disks are the disk type that existed before Windows 2000; most disks are basic disks. Dynamic disks are disks that once were basic but were changed to dynamic using Windows 2000, Windows XP, or a product in the Windows Server 2003 family. If you plan to install to a dynamic disk, you cannot change the volume or partition sizes on the disk during Setup, and therefore no planning is needed regarding partition sizes. Instead, review the guidelines in Working with dynamic disks and Setup.

Disk partitioning is a way of dividing your physical disk so that each section functions as a separate unit. When you create partitions on a basic disk, you divide the disk into one or more areas that can be formatted for use by a file system, such as FAT or NTFS. Different partitions often have different drive letters (for example, C: and D:). A basic disk can have up to four primary partitions, or three primary partitions and one extended partition. (An extended partition can be subdivided into logical drives, while a primary partition cannot be subdivided.)


  • If you plan to delete or create partitions on a hard disk, be sure to back up the disk contents beforehand, because these actions will destroy any existing data. As with any major change to disk contents, it is recommended that you back up the entire contents of the hard disk before working with partitions, even if you plan to leave one or more of your partitions alone.

Before you run Setup to perform a new installation, determine the size of the partition on which to install. There is no set formula for figuring a partition size. The basic principle is to allow plenty of room for the operating system, applications, and other files that you plan to put on the installation partition. The files for setting up Windows Server 2003 require approximately 1.25 GB to 3 GB on an x86-based computer and 3 GB to 4 GB on an Itanium architecture-based computer, as described in the topics about system requirements listed in System Requirements and Hardware Compatibility. It is recommended that you allow considerably more disk space than the minimum amount. It is not unreasonable to allow 4 GB to 10 GB on the partition, or more for large installations. This allows space for a variety of items, including optional components, user accounts, Active Directory information, logs, future service packs, the paging file used by the operating system, and other items.

For information about some of the items that require space on the disk, see the following:

When you perform a new installation, you can specify the partition on which to install. If you specify a partition on which another operating system exists, you will be prompted to confirm your choice.

During Setup, create and size only the partition on which you want to install Windows Server 2003. After installation is complete, you can use Disk Management to manage new and existing disks and volumes. This includes creating new partitions from unpartitioned space; deleting, renaming, and reformatting existing partitions; adding and removing hard disks; and changing a basic disk to the dynamic disk storage type, or dynamic to basic. (If you want to have a dynamic disk on a computer that contains more than one operating system, be sure to read Considerations for computers that contain more than one operating system.)

On Itanium-based computers with more than one disk, on x64-based computers, and on x86-based computers running Windows Server 2003 with Service Pack 1 (SP1), you can plan to choose not only the sizes of partitions but the partition style for each disk. The partition style determines the way that information about the partition is stored. There are two partition styles: master boot record (MBR) and GUID partition table (GPT). On GPT disks, unlike MBR disks, data critical to platform operation is located in partitions instead of unpartitioned or hidden sectors. In addition, GPT disks have redundant primary and backup partition tables for improved partition data structure integrity.

On Itanium-based computers, you must install Windows XP 64-bit Edition (Itanium) or the Itanium-based versions of Windows Server 2003, Enterprise Edition, or Windows Server 2003, Datacenter Edition, on a GPT disk. On x86-based and x64-based computers running Windows Server 2003, you must install Windows on an MBR disk. Other disks can use either the MBR or GPT partition style. With GPT disks, you can create more partitions and larger volumes, and can take advantage of other benefits. For more information about GPT disks, see GUID partition table. For more information about MBR and GPT partition styles, see Partition styles. For information about obtaining the Windows Server 2003 Resource Kit, see Using the Windows Deployment and Resource Kits.


  • If you are setting up a computer so that it contains multiple operating systems, you must install Windows Server 2003 on its own partition or logical drive. This ensures that Windows Server 2003 will not overwrite crucial files that are needed by the other operating system. For more information, see Deciding Whether a Computer Will Contain More Than One Operating System.

Disk partition requirements for Remote Installation Services

If you plan to use Remote Installation Services on this server so that you can install operating systems onto other computers, a separate partition for use by Remote Installation Services is necessary. Plan on using NTFS on this partition: NTFS is required for the Single Instance Store feature of Remote Installation Services.

If you need to create a new partition for Remote Installation Services, plan on doing it after Setup, and leave enough unpartitioned disk space so that you can create it (at least 4 GB of space is recommended). As an alternative, for the system disk (not cluster disks), you can plan to make the disk a dynamic disk, which allows more flexibility in the use of the disk space than a basic disk. (However, if you want to have a dynamic disk on a computer that contains more than one operating system, see Deciding Whether a Computer Will Contain More Than One Operating System.)

For information about requirements for Remote Installation Services, see Remote Installation Services system requirements. For additional information about disk and partition choices, see Disk Management. For an overview, checklists, and other information about Remote Installation Services, see Remote Installation Services.