In old Windows XP and Server 2003, you can only do some basic operations in Disk Management such as create, delete and format partition. To change size of allocated partition, you need to run DiskPart command prompt. It is a bit difficult to most of personal computer users, thus, from Windows Vista, Microsoft added new Shrink Volume and Extend Volume functions with graphical interface. Windows Server 2008 and all subsequent versions inherited these two functions with same GUI.
As the name, Extend Volume is used to expand allocated partition without data loss, however, because of many limitations of this function, most of partitions can't be extended. Many people feedback that Extend Volume greyed out in Disk Management. Searching by Google and you'll see many similar complaints such as "Windows 10 won't let me extend volume", "extend volume is disabled for C drive", "extend volume option is grayed out and doesn't work".
This article introduces all possible reasons why Extend Volume option is grayed out and the corresponding solutions.
There are 5 common reasons that why Extend Volume greyed out in Disk Management and I'll explain one by one.
Unallocated space is part of free disk space that is not used by any volume, it can be used to create new volume or combine into other ones. As we know, a 256GB physical hard disk drive can't be increased to 512GB. Therefore, before extending a partition, there must be Unallocated space on the same disk, otherwise, Extend Volume will be grayed out when you right click any drives in Disk Management.
There are 2 ways to get Unallocated space: delete and shrink volume.
This is the most common reason why Extend Volume greyed out on both Windows Server and PC.
When shrinking a volume, the only option in Disk Management is entering an amount to shrink. You cannot choose to make Unallocated space on the left or right side of this partition. It is not an issue if you just want to decrease a partition, but if you want to extend a partition by shrinking another one, it is impossible in Disk Management, because Extend Volume only works when there's contiguous Unallocated space on the right.
As you see, there is 20GB Unallocated space generated after shrinking my D drive.
The only way to enable Extend Volume for drive C is by deleting the adjacent drive D. But to drive E, there is no way in Disk Management.
Do NOT delete drive D if you installed programs into it, and remember to transfer files first if you can delete it.
Both Shrink and Extend Volume functions only support the partition that are formatted as NTFS or without file system (RAW). Thus, if you right click FAT32 or any other types of partitions, Extend Volume option is grayed out.
In my test computer, there is 59.46GB Unallocated space that is adjacent and on the right side, but drive D is FAT32, so Extend Volume doesn't work.
In GPT style disk, all partitions are created as Primary, but in MBR disk, there could be both Primary and Logical partition. Unlike Primary partitions that work as independent unit, Logical Partition is part of the Extended partition. Extended partition works like a container and the disk space of Logical partition will be converted to Free after deleting.
Free space deleted from Logical drive can't be extended to any Primary partition, Unallocated space deleted from Primary partition can't be extended to any Logical drive.
Nowadays, hard disks are much larger and it is common to use 2TB+ disk for personal computers. To a server, it is common to use over 10TB RAID array via several large disks. But if you initialized the disk as MBR, you can use only 2TB space, the remaining space can be created new or added to other volume in Disk Management.
As the screen shot shows, drive H is formatted as NTFS and there is right contiguous Unallocated space, but Extend Volume still greyed out. When I right click this Unallocated space in Disk Management, all options are grayed out.
Steps to fix Extend Volume greyed out issue in Disk Management (for both Windows Server and PC):
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