
Reason 2: The un-allocated space is not contiguously behind the target partition that you want to extend.

Solution for reason 1: Convert MBR to GPT disk for using un-allocated space beyond 2TB. Your disk partition is MBR style that supports only up to 2TB. Reason 1: The cause is disk partition style. How to solve Windows Server 2012 (R2) Extend Volume Greyed Out issue? You are trying to extend partition with Disk Management snap-in Windows Server 2012 (R2), but you find the option to Extend Volume greyed out. wmic diskdrive get model, serialNumber, size In order to detect hard drive model, serial number and size use the command below. DISKPART> clean DISKPART> convert gpt DISKPART> exit DISKPART> list disk DISKPART> select disk 0 - the disk should be selected, the number may be different in your machine. If you need to convert a disk to GPT while installing Windows then you can press Shift + F10 or Fn + Shift + F10 to open Command Prompt when you arrive the Windows Edition Selection screen. When initializing a new external drive, probably you should initialize your disk as a GPT disk unless you want to install an old operating system on your external disk. However it can recognize more than 2TB space, and allows you to create more than 4 partitions. GPT (GUID Partition Table) disk does not allow you to install older operating systems. However it can only recognize up to 2TB space, and allows you to create up to 4 partitions. MBR (Master Boot Record) disk allows you to install older operating systems.

Which option should you choose when initializing a new external drive? Answer:

What is the difference between MBR disk and GPT disk? Only use this option if your hard disk has been previously formatted and you are sure that your hard disk is not damaged. When you choose to run a Quick Format on a volume (or partition), format removes files from the partition, but does not scan the disk for bad sectors. The scan for bad sectors is responsible for the majority of the time that it takes to format a volume. When you choose to run a Full Format on a volume (or partition), files are removed from the volume that you are formatting and the hard disk is scanned for bad sectors.

Which option should you choose when formatting a drive? What is the difference between Quick Format and Full Format?
