Literally, it means space that hasn’t been allocated to other partition or new partition, unallocated space can be created by the function Shrink Volume and Delete Volume in the built-in tool Disk Management, and it can be used for creating volume or extending other partition with low disk space
In the page, we listed some usage of unallocated space for both Windows Client OS and Server OS, hope they can be some help
Regarding the above problem, the only available way is to delete the secondary D partition and mike as unallocated space. Before executing deletion, we have to backup and restore the data, it is really time-consuming. To break such flaw of built-in Disk Management, the safest and the most effective method is to use the known server partition magic alternative – Macrorit Partition Expert Server Edition.
In fact, unallocated space cannot be deleted but can be well used. Just allocate it to other partition or create a new partition on it. You can right-click on the unallocated space and check what you can do about it. There’s New Simple Volume option in the menu, if you don’t want to create partition on it, or cannot create the fifth partition on the disk, you can right-click on the partition ahead of it, and you may find Extend Volume of that partition is active, so this is what you can do about the unallocated space.
When we run Windows Disk management in Windows 7 or Windows 10 sometimes, we may find unallocated space, or free space is next to some partition. How to make use of them? Actually, we can create a partition with unallocated space in Disk management, and we can extend some partition which is running of space, C Drive for example, in partition software. If the unallocated space was shrinking from other partition, you cannot use it to extend volume, because the location is wrong; but if you deleted some partition to created space unallocated, it can be used to extend the partition ahead of the deleted one.
When deleting a logical volume on the Extended partition, deleted space becomes Free space, while deleting a primary partition, deleted space turns to Unallocated space. So, when we’re about to active the Extend Volume option in C Drive, we have to delete all the logical partitions on the Extended partition to make that area unallocated. Unallocated space is blue while Free space is green in color.
An unallocated space is the last block of files or unused part of the cluster, Usually, our file system interface has no access to the unallocated space, because the Windows system does not allow access to past the place at the end of a file. In the meantime, Drive C alerts us a low disk space when an unallocated space available in windows 10. Most of us will merge unallocated space to Drive C in windows 10 instead of leaving it alone.
Windows Server 2012 disk management has a great change on Windows Server 2003, Extend Volume, Shrink Volume and Windows Storage Space are added to server manager for better managing Server 2012 disk space, we’ll have detail guide on how to use Extend Volume, Shrink Volume and Unallocated space.