Windows - Disk Usage

​To check disk usage, you can open up the computer management utility then head ​to the disk management console.   ​From there, you right-click on the partition you’re interested in and ​select properties. ​This will bring up the general tab where you can see the used and ​free space on the drive. ​ In addition to using this graphical user interface to check the disk usage, ​Windows provides a command line utility called disk usage as part of its sys ​internals tool offering that DU utility can print out the usage of a given ​disk and tell you how many files it has. ​

•  ​It can be useful for creating scripts which might need text-based output instead ​of visual reports, like the pie chart and disk management.

​On the same tab in the disk management console, ​you might notice a button that says disk cleanup. ​If you press this button, Windows will launch a program called clean ​manager.exe which will do a little housekeeping on your hard drive to try and ​free up some space. 

• ​This housekeeping includes things like deleting temporary files, compressing ​old and rarely use files, cleaning up logs, and emptying the recycle bin.

The idea behind disk Defragmentation: A process of taking all the files stored on a given disk and reorganizing them into neighboring locations

•  ​Having files ordered like this will make life easier for rotating hard drive ​disks that use an actuator arm to write to and read from a spinning disk. ​The head of the actuator arm will actually travel less to read the data it needs.
• less beneficial for SSDs For SSDs, the operating system can use a process called trim ​to reclaim unused portions of the solid-state disk. ​Defragmentation in Windows is handled as a scheduled task.

To kick off a manual defragmentation, ​open up the disk defragmenter tool bundled with the OS. ​Type disk defragmenter. ​ When it launches, you’ll be given a list of disks which can be defragmented ​along with buttons to analyze the potential gains from running a defrag or ​defragmentation, and to run the defrag itself.

For more information about disk usage in Windows, check out the following links: Disk Usage, How to start Disk Cleanup by using the command line.