By Bryce / Last Updated March 31, 2021

Overview of a  primary partition 

A primary partition is a volume where an operating system can be installed. An MBR disk can hold up to four primary partitions. A GPT disk is able to hold 128 primary partitions.  An active partition is based on a primary partition. There can be 4 primary partitions and only one active partition on an MBR disk.

Any primary partition can be set as active that contains the boot loader to load the operating system. A primary partition can be a drive where the operating system is installed or a drive that stores regular data. Generally speaking, only one primary partition is essential, which is known as C: drive.

The necessity of extending primary partition on Server 2008 (R2)

It is common that primary partition (partition C) is stored with more and more applications and data, the usable space of it becomes less and less in Windows Server 2008 (R2). What’s worse, partition C running out of space can have a negative impact on operating system running speed and applications response speed and it even can cause system crash. To avert insufficient space trouble, why not increase partition size of primary partition on Windows Server 2008 (R2) rather than free up space?

2 ways to extend primary partition on Windows Server 2008 (R2)

Two effective ways of increase primary partition space will be listed below and you can choose the one you like.

Way 1.  Extend Volume via Windows Server 2008 (R2) Disk Management [Data Loss]

Disk Management is a tool built-in Windows Server 2008 (R2) and it allows you to shrink and extend partition. It is available to quickly access Disk Management by pressing "Windows" +"R" and typing diskmgmt.msc and hitting “Enter”. You can enlarge primary partition when there is contiguous unallocated space behind it; otherwise, you’ll find the option of Extend Volume greyed out when right-clicking C drive to extend it. Then, how can you extend C drive in Windows Server 2008 (R2)?

Extend Volume Greyed Out Windows Server 2008

It is recommended to apply third-party partition software for Windows Server 2008 (R2) to extend primary partition. But if you are insisting to employ Disk Management, you can refer to the following instruction.

1. To get adjacent unallocated space behind the C drive, you need to delete the partition adjacently behind the C drive (back up important data before deleting).

2. Then, it is able to increase C: drive size with Disk Management. Click C: drive and choose extend volume.

✎ Tips:
◆ Both free space and unallocated space and unallocated space refer to storage space that doesn’t hold data in different ways. Free space can’t be used to extend the primary partition and unallocated space can’t be applied to extend logical partition.
◆ If you are familiar with the Windows command prompt, you can extend partition with Diskpart. But this also demands an unallocated space contagious to the partition you need to extend.
◆ If the partition right behind C: drive is an extended partition, you have to delete all the logical drives on the extended partition. Then delete the extended partition to get an unallocated space for extending C drive.

Way 2. Extend primary partition via third party software [Without Data Loss]

Obviously, it is bothering and time-wasting to extend C: drive via Disk Management or Diskpart on Windows Server 2008 (R2) if there is no contiguous unallocated space right behind the primary partition that you want to extend.

Fortunately, AOMEI Partition Assistant Server can allow you to add non-contiguous unallocated space into a partition; and it enables you to extend a partition easily and conveniently through allocating free space to it directly when there is no unallocated space. Then, refer to the following part which shows how to extend Windows Server 2008 (R2) primary partition C with AOMEI Partition Assistant Server. You can download the demo version of AOMEI Partition Assistant Server to have a try at first.

Download Demo Server 2008 (R2)/2012 (R2)/2016/2019
Secure Download

Step 1. Install and run AOMEI Partition Assistant Server. Right-click partition C on Server 2008 (R2) and choose Merge Partitions.

Merge Partitions

Step 2. Tick the box before “Unallocated” to extend C: drive and click OK.

Choose Unallocated Space

Step 3. Check the pending operations; click Apply and Proceed to implement this task.

Apply Proceed

✍ Notices:
✔ A reboot is necessary as this operation involves system partition.
✔ "Free space” and “unallocated space” shall be marked as the same type – “unallocated”. That is to say, AOEMI Partition Assistant enables you to add free space on extended partition to primary partition.
✔ AOMEI Partition Assistant can merge unallocated space with C: drive no matter whether the unallocated space is right behind the primary partition or not.
✔ If there is no unallocated space or free space on the disk hard drive, you can shrink partition to get it. Or you can allocate free space from one partition with adequate space to C drive to extend C drive.


There is no doubt that AOMEI Partition Assistant Server can extend primary partition on Windows Server 2008 (R2) effortlessly and securely. Apart from Windows Server 2008 (R2), it is workable with Windows 2019/2016/2012 (R2)/2003 as well. As an overall and powerful partition tool for Windows Server, it is equipped with many other functions about disk and partition, such as splitting partition, wiping partition, copying partition, and so on. And to manage hard drives and partitions for unlimited PCs within one company, you can use AOMEI Partition Assistant Unlimited