By AOMEI / Last Updated July 29, 2019

What is the RAID 5 unallocated space?

Unallocated space refers to a span of space on a hard drive with nothing on it. If such empty space is in extended partition, it is called free space. Allocated space, opposite to unallocated space, is a partition or volume with file system that you can read or write data on. Usually, to configure a new internal hard drive, you need to initialize it and create partitions out of unallocated space before you can store data. If you delete or shrink a volume, you will get unallocated space. On RAID 5 drive, the RAID controller may also cause unusable unallocated space. If your RAID 5 drive was initialized as MBR disk, the space beyond 2TB will become unallocated space that cannot be easily used to create new partition or extend existing partitions unless converting MBR to GPT.

How to create new volume with the unallocated space?

In general, you can use Windows built in utility Disk Management to create a new partition with the unallocated space on RAID 5. To access Disk Management in Windows 10/8/7 or Windows Server 2016/2012/2008, you can press Windows + R, in the Run Window, type “diskmgmt.msc” and press Enter.

To create new volume with Disk Management:

1. Right click on the unallocated space and select “New Simple Volume”.

New Simple Volume

2. Specify the volume size and click “Next”as the New Simple Volume Wizard instructs.

Volume Size

3. Assign drive letter or path and click “Next”.

Drive Letter

4. Choose a file system and specify the volume label if you like.

File System

5. Click “Finish” to close the Wizard and start the format.


It will not take a while to finish formatting the new created volume with Disk Management. However, there are some cases, Disk Management is unable to create new volume. For example, there are already 4 primary partitions on an MBR disk. In that case, you can use third party partitioning software AOMEI Partition Assistant to create more than 4 partitions on an MBR disk without a scratch.

How to add unallocated space to RAID 5 array?

If you don’t want to create another partition on your disk, you can add the unallocated space into one of the existing partition. Disk Management can only add unallocated space into the contiguous partition that before the unallocated space. Therefore, you can use free partition manager software AOMEI Partition Assistant Standard to merge unallocated space with any partitions on the RAID 5 drive.

1. download and run this software.

2. Right click on the partition to be merged with and select “Merge Partitions”.

Merge Partitions

3. In the next screen, check the unallocated space and the target partition, and click “OK” to continue.

Select Unallocated Space

4. Then you can preview the partition layout without making any changes on your disk. If it contents you, click “Apply” to save the changes.


After that, AOMEI Partition Assistant will expand raid 5 volume, which will be finished in a short while. If you are unable to use the unallocated space beyond 2TB, then the RAID 5 drive is an MBR disk. To reclaim the space beyond 2TB, you need to convert RAID to GPT disk with this this software, which will not cause data loss or affect your OS in the conversion. As a conclusion, no matter what situation you are in, AOMEI Partition Assistant can help you manage the RAID 5 unallocated space effortlessly.