How to Extend a Disk Partition in Windows Vista and Server 2008

by Daniel Petri - January 8, 2009

Microsoft operating systems, starting from Windows NT 4.0, Windows 2000, Windows XP, and now Windows Vista and Windows Server 2008, have always had a built-in method of extending or expanding a partition that was configured on the computer's physical hard disks. While shrinking partitions was not possible internally, and usually required usage of 3rd-Party tools, expanding partitions was relatively easy, but did have its limitations. Now, unlike previous Microsoft operating systems, Windows Vista and Windows Server 2008 allow for an easy, out-of-the-box, method of expanding those partitions and making them larger, while reliving us of these previous limitations.

This is made possible by using the Extend feature in Disk Management, or in the DISKPART command line executable. When you extend a partition, all data on the existing partition will NOT be erased, but it's better to be safe than sorry, therefore I always recommend using a good backup procedure to back up your data, just in case.

Extending a partition in Windows Server 2008 is similar to the process in Windows Vista. I've used screenshots of Windows Vista, except the ones related to Server Manager in Windows Server 2008. The rest of the procedure is the same.

Extending a partition by using the GUI

  1. Like in most administrative tasks, you must logged on as an Administrator.
  2. In Windows Vista, go to Control Panel --> System and Maintenance > Administrative Tools, or on the My Computer context menu. Select Computer Management. In Vista, if you are prompted for an administrator password or confirmation, type the password or provide confirmation.
  3. In Windows Server 2008 you need to go to Server Manager, found in the Administrative Tools folder or on the My Computer context menu.
  4. Next, scroll down till you get to the Storage section, and in it go to the Disk Management console.
  5. Select the disk you want to extend, for example Drive C.
  6. Note: Extending any volume is fine as long as you have additional unallocated free space on that same physical hard disk . Note that you can also extend the partition beyond the physical disk it is located on. This is useful when you run out of space on that physical hard disk, and have brought in a new physical hard disk that you wish to use. However, unlike using that new disk as a totally new partition by itself, this disk (or part of it) becomes a part of a partition located on the first disk. While useful in some cases, this scenario might cause fault tolerance issues, because this extended partition is NOT fault tolerant, and if something happens to one physical disk, all the data on that extended partition becomes unavailable, and data loss can occur. In any case, such an extended partition can contain an unlimited number of logical drives.

  7. Right-click the disk and select Extend Volume.
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    Windows Server 2008 it looks like this:

  9. Click Next.
  10. Windows Vista tell you how much space can be added to the existing partition. You can manually enter the amount of space you want to add by changing the "Select the amount of space in MB" values. However note that you cannot enter a higher value than the value already present. As noted above, if you have additional physical hard disks that have unallocated free space, you can add that space up and further extend the partition to span multiple disks. Again, be warned, this configuration is NOT fault tolerant. In case one of the disks malfunctions, you will lose your data.
  11. The process will finish quite quickly, and a reboot is NOT required.

Extending a partition by using the command line

Extending a partition or volume can be done via the CLI, or command line interface. This works in both Vista and Windows Server 2008. In order to do that perform the following steps:

  1. Click Start and type CMD, then press Enter.
  2. In the command prompt type
    Diskpart
  3. Select the right disk drive and partition to work on. Typically this should be disk 0 and partition 1, but YMMV.
    Select disk 0
    Select partition 1

    Note: You may want to perform a LIST operation to view your existing disks and partitions BEFORE attempting to expand the wrong one. Needless to say, if you don't have any space you can use on the same disk, you will NOT be able to extend the partition any further. So no real harm can be done here.

    List disk
    List partition
  4. When the right disk and partitions were selected, perform the EXTEND command. If you don't specify the size to extend by, then the command will extend the partition by using all of the contiguous space available on that disk.
  5. Extend size=500

    The above command will extend the partition by 500 MB.

    Extend

    The above command will extend the partition by using all of the contiguous space available on that disk.

And with that, we are all done!

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