Monitoring and how to increase disk space in Ubuntu
What you will Learn:
Commands to monitor CPU (uptime, top)
Command to monitor memory (free -h)
Command to monitor disk usage (df)
Increase hard disk space on ubuntu
Commands to monitor CPU
The uptime command will tell us the uptime for our server and the average load on server. Load server gives an indication of how loaded the server is over last 1 minutes, 5 minutes, 15 minutes. So in a system with 1 CPU, if the load average is 1, that means there is exactly 1 process running in that server and that cpu is fully utilized. Our Ubuntu has 1 CPU and hence the server is under-utilized, since the 3 values are less than 1 
If the server has 2 CPUs and if the load avg is greater than 2, it means that server is overloaded.
The ‘top’ command gives information about the top CPU processes plus other details
Command to monitor memory
The ‘free -h’ command tells us the details about memory usage
Command to monitor disk usage
‘df -h’ gives details of disk usage. You can see that root partition is 79% used and only 2 giga bytes is left (df is for disk free)
Increase hard disk space on ubuntu
To increase hard disk space on Ubuntu VM, perform following steps. Search for ‘System Monitor’ app and Hit Enter
Click ‘File Systems’ tab, see below
As seen above, right now we have one VM disk of 10 GB. We have used around 7.4 GB and 2.1 GB is left. Close this app.
Now search for ‘Disks’
See above.
Right now we see 11 GB hard disk space in total:
Filesystem partition 1 (/dev/sda1) has 537 MB
Extended partition 2 (/dev/sda2) has 10 GB, see below
Filesystem partition 5 (/dev/sda5) has 10 GB and is 75.1% full, see below
Close the Disks app.
Let us now expand the disk size from 10 GB to 20 GB
First let us ‘Power off’ the Virtual machine
Once the machine is powered off, right click and click Settings
Go to Storage and under Controller: SATA you would find the machine name, juts make a note of it 
Close the above ‘Settings’ window
Next, File > Virtual Media Manager
Below window comes up
The machine name Ubuntu1.vdi is the same name that we saw earlier on the storage section of ‘Settings’ window. Notice that it currently shows virtual size 10 GB
Click properties icon 
See below, attributes section comes up showing current size as 10 GB
Enter 20 GB, see below
Click Apply
Notice above that virtual size is now 20 GB
Click Close
Power on the machine by clicking ‘Start’
Search for the Disks app
See below, we can see free space of 11 GB
Now, select extended partition 2
Click ‘Additional partition options’ icon 
Click resize
See above, increase partition size to maximum 
Click Resize
Below window comes up
Authenticate
Notice below that size is now 21 GB
Similarly, select filesystem partition 5
Click ‘Additional partition options’ icon
Click Resize and increase partition size to maximum
Click Resize
Once resizing process is complete, close ‘Disks’ app (above window)
Open terminal, execute df -h command, notice below that 12 GB disk space is now available. So we have been able to successfully increase the disk space by additional 10 GB
Thank you for reading!