Computer Pops Up “Low Disk Space”
Warning
After long time usage of our computer, it will pop up a
warning message says “Low Disk Space – You are running out of disk space on system
(C:) To free space on this drive by deleting old or unnecessary files, click
here…”

As the message has make it clear, the computer system partition
is in low disk space problem. It will influence the performance of operating system;
the most common presence is that computer becomes slower and slower. As the message
also mentioned, we can remove unused files to get free space. It does help but
cannot solve this problem completely.
If we do clear out system C partition and does get it
released, after a period of time, low disk space problem probably will come back.
Delete unnecessary files will only free a small part of disk space; it can only keep
away from the warning message for a short period of time.
To completely solve low disk space problem, we should allocate
free space to C drive form unallocated space or other partitions.
How to Increase Space in C Drive Using Disk
Management?
Yes, we can increase space in c drive using Disk
Management (DM). Yet, only when there is unallocated space very behind C drive, can
it be increased by DM. Otherwise, will C drive extend volume greyed
out. If there is unallocated space, how to move
unallocated space to c drive? If there is not, how to allocate
free space from one partition to another?

Thus, we should first create unallocated space and make
sure it locates right behind system partition. Then, extend C drive with the
unallocated space. To make unallocated space, we can either shrink some from other
partitions or by deleting existing partitions. However, the unallocated space must
be located very behind partition C. Therefore, the only choice is to delete the
volume which lies very behind C and make it unallocated.
How to Increase C Drive Space from D Drive?
Next, I will show an example of how to increase c drive
space from d drive (the drive which is very behind C).
Step1. Open Disk Management, right click partition D and
choose Delete Volume.

Notes:

If the volume to be deleted is in use, it will inform us of that. We can
force the deletion of the partition. Yet, forcing a deletion might cause
unexpected errors in the application that is using this partition. Please be
careful.

Step2. The process completes in seconds. When it
finishes, we can see the space originally belongs to D volume becomes unallocated
space and locates very behind C drive.

Tip: If the unallocated space is
not enough, we can continue to delete the next partition to create more unallocated
space.
Step3. Right click on C drive and select Extend
Volume.

Step4. Extend Volume Wizard will pops up. Just click Next
to continue.

Step5. In this window, select the disk(s) from which we
want to get free space. Here, both partition C and the deleted D partition is on
Disk 0, and Disk 0 is the only disk from which we can take free space. Thus, Disk 0
is automatically selected for us. Specify how much free space we want to add into C
drive (in default, it will merge
all unallocated space into target volume), then click Next.

Tip: Even if there is another hard
disk and there is much unallocated free space on it, we can’t add the unallocated
space to the C drive for a basic disk volume can’t own space on more than one hard
disks. The space of dynamic disk volume can lies on different hard drives. Thus, if
the basic volume we are going to extend lies on a hard drive which only contains
data, we can first convert the whole disk into dynamic, and then extend the volume
(now becomes dynamic volume) with unallocated space on another hard disk (it should
also be dynamic disk). If the basic hard disk has system installed on it, we are not
recommended to turn it to dynamic. Convert a system basic disk to dynamic may cause
system unbootable. To conclude, to extend a system basic disk partition, there must
be an unallocated space on this disk and right behind this partition.
Step6. This is summary of the operation DM will carry
out. Check it carefully. If it is all right, click Finish.

Step7. In only a few seconds, we can have our system C
drive extended.

Allocate Free Space from One Partition to Another
without Formatting Hard Drive
As we can see above, Disk Management can help us extend
system C drive in seconds. However, the disadvantages is that it has to format other
drives to allocate free space from one partition to another. Yet, is there a way to
allocate free space from one partition to another without formatting hard drive?
To allocate free space from one partition to another
without formatting hard drive, we should rely on third party software like AOMEI Partition Assistant.

With its Extend
Partition Wizard, Resize Partition or Allocate Free Space feature, no matter
which one, we can increase space in C drive without formatting other drives when
there is no unallocated space on the hard disk.