1. Introduction to Computers
Storage Optimization For Operating Systems

2. Windows
All operating systems run better when there is free space on the hard drive. As a rule of thumb, we tend to want over 20% of our storage space free
Another major part of keeping a Windows disk optimal is keeping the disk defragmented
While modern Windows systems do a good job at maintaining our storage and optimizing our disks, it is still good to be familiar with the diagnostic and maintenance tools for troubleshooting purposes

3. Windows - Disk Properties
If you right click on a disk in file explorer and click Properties the general tab gives us a good read out of our overall disk use
This is also where we can access Disk Cleanup for this specific drive, as opposed to the general Disk Cleanup for all drives from Control Panel
One option we didn’t look at for Disk Cleanup is “Clean Up System Files”. This allows us access to other, typically unnecessary files
If regular disk cleanup won’t remove enough space, you can choose to clean up the system files to give you more options

4. Windows - Error Checking
We can access the disk’s error checking and defrag utilities from right click -> properties again, but this time going to the tool tab
Error Checking happens periodically in modern systems automatically to keep your system’s disks healthy, but we can force a check manually
Error Checking is going to check for bad clusters like we mentioned as well as physical damage on the hard drive’s platter
If we need more detail on how the error checking went we can click on show details which is going to bring up event viewer

5. Windows - Defragment
Like Error checking, defragment used to be a mandatory user maintenance step, but it is now mostly automated. To run it manually, we select it from the same tab as error checking
The defragment tool will make multiple passes, analyzing clusters on the system and then moving them closer to the other clusters belonging to that file
While it is good to defragment hard drives regularly, please note that due to how solid state drives work, not only is defragmenting not necessary, it actually shortens the drive’s lifetime

6. Linux
Unlike Windows systems, Linux systems don’t really need to be defragmented
This is because the Linux file system (ext4 for most modern Linux systems) stores files scattered throughout the drive. This means that when files need to be saved there is usually plenty of large chunks of free space to store, and when files need to expand there is space for them to do so
We still need to know utilities for exploring and managing disks though

7. Linux - df
Df shows how much disk space is used by each file system, separated by partition
Df without modifiers will output the data as blocks of storage space. To output the space used and available as megabytes and gigabytes, we can use the modifier -h, which stands for human readable
Df also shows how much space is allocated to the partition, how much space is available, the percentage of total space used and where the partition is mounted to

8. Du
Du - shows less information about the file system, it only shows the space used, but it can sometimes be very useful
Du shows the data used at a directory level. This lets you see if there are any folders taking up an abnormal amount of space
Du runs recursively, showing the information for the present working directory and all directories stored within it
Alternatively, a directory can be specified to show information about a different directory
Just like df, du needs the -h modifier to output data in a human readable format instead of as number of data blocks

9. Fsck, umount and mount
Fsck stands for file system check, and is used to check for errors in the file system
The file system must be unmounted with the command umount before being checked with this command
A file system that is mounted can be accessed by the users by navigating to where it is mounted in the directory. If a partition is unmounted it can no longer be accessed
Mount can be used to re-mount the partition. The syntax is mount -t [FILE SYSTEM] [PHYSICAL DRIVE] [MOUNT POINT]

10. Mac
Since the Mac OS is built on Unix, like Linux, there is no need to defragment it, but we do have tools to explore and manage the file system
The most basic way to get information about a directory is by pressing command+i or right click -> Get Info

11. Disk Utility
Disk Utility gives us a higher level overview of the disk usage
This includes storage space used, storage space available, connection used, and the type of file that is using data. This gives us a good idea of the types of files to look at for deletion if we’re trying to gain space on the hard drive
This utility will look very familiar if you are used to the Iphone’s storage app

12. First Aid From disk utility, we can access the first aid utility
The first aid utility allows us to
This is most effective when booting into recovery mode because otherwise there will be some system files that can’t be checked or repaired since they will either be in use or protected while the system is running normally
To see more detailed information of the check and repair, click on show details

13. Fsck
Since Macs are built on the foundation of Unix we can access some of the same disk utilities as Linux
For example, if we restart the system we can enter single user mode which is the Mac command line maintenance utility
From here we can execute commands like fsck to check the file system health
In this example we ran fsck with the -fy option to automatically fix any errors found