This is quite a common requirement as you start to scale and/or change your infrastructure – how to check the available disk space on a virtual machine using Linux and/or an AWS EC2 instance. It’s one of these things that you would think in this day and age is easy to view, yet on the vast majority of systems this metric seems awkward to get your hands on with a simple click. You want something as simple as how you can see on Micro$oft Windows the percentage% of disk space you have used and what you have got left. This is all a really basic requirement that you’d think would be simple to get your hands on this information on Linux and AWS EC2, but hey, Linux is Linux and AWS EC2 is AWS EC2…..
So, let’s get into the detail.
Thankfully this is actually a really easy piece of information to get your hands onto. For the quick answer, just run the following command when you’ve SSH’d into your Linux instance;
df -hT
What you will find when you run the above command on Linux to view the available hard disk space and current usage is something along the lines of the below image;
What you can see here is that the disk is currently only being used at 15% capacity. Awesome. You’ve got space to play with.
To help your understanding with some of the cryptic Linux commands;
- df = Disk Free command
- -h = Human Readable, print sizes in human readable format (e.g., 1k, 234M, 2G)
- -T = Print Type, print file system type
There are many other handy commands to the Disk Free utility on Linux, but for the purpose of this blog post these are the main ones you need to be concerned with. Ultimately you can keep track of the disk usage on your Linux machines so you know when it’s time to upgrade your hard disk to increase capacity.
Hopefully it’s obvious why you should care about this stuff… if your hard disk is full on your web server, then this can result in catastrophic results where your ecommerce customers can’t even place orders on your website, or where your B2B customers can’t even complete the contact form on your website. These are just some of the surface level issues that can come up. In essence, when your disk gets full – you’re screwed. It causes an unbelievable amount of problems under the hood that take a significant amount of time to resolve. Don’t underestimate keeping track of this core metric.
Michael Cropper