Extend C Partition is needed when you found low disk space notification on you Server 2012 system, but users found that they can't extend partition because Extend Volume grayed out on Windows 2012. How to extend C partition then? My data on this Server must stay safe.
Without data loss? How about backup data in other partition, and then recover them after partition had been extended? If you have no problem without that, we can extend C partition in Disk Management.
Preparations: an external hard drive for data backup, or a partition with large empty size.
Extend Volume greyed out mainly cause by the follow two reasons:
A: File System is not NTFS, if you have FAT32, FAT16, Disk Management will not work on that partition.
B: The partition you just deleted is not continuous to C Drive, which means you have another partition between C partition and unallocated space.
Since Disk Management can't move unallocated space near to C Drive, you have to delete the very partition right near to OS partition, that's the limitations on Disk Management, if what you're requiring is just data safe, just delete another partition after backup.
Partition Extender is the one extends C partition without data loss not in a backup data way but in a way to keep data intact, because Extender will not touch data in you partitions. Therefore, there's no need to move data from one partition to another, Do as follow to have you C partition extended:
Preparations: Download and install Partition Extender Server Edition.
Then, Extender reloads disk-map, showing you a new C partition.