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”.

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

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

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

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”.

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

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.