Google Cloud has always had a knack for non-standard virtual machines, and their option of creating Google preemptible VMs is no different. Traditional virtual machines are long-running servers with standard operating systems that are only shut down when you say they can be shut down. On the other hand, preemptible VMs last no longer than 24 hours and can be stopped on a moment’s notice (and may not be available at all). So why use them?
Use Cases for Google Preemptible VMs
As with most trade-offs, the biggest reason is cost. Preemptible VMs can save you up to 80% compared to a normal on-demand virtual machine. (By the way — AWS users will want to use Spot Instances for the same reason, and Azure users can check out Low Priority VMs). This is a huge savings if the workload you’re trying to run consists of short-lived processes or things that are not urgent and can be done any time. This can include things like financial modeling, rendering and encoding, and even some parts of your CI/CD pipeline or code testing framework.
How to Create a Google Preemptible VM
To create a preemptible VM, you can use the Google Cloud Platform console, the ‘gcloud’ command line tool, or the Google Cloud API. The process is the same as creating a standard VM: you select your instance size, networking options, disk setup, and SSH keys, with the one minor change that you enable the ‘preemptible’ flag during setup. The other change you’ll want to make is to create a shutdown script to decide what happens to your processes and data if the instance is stopped without your knowledge. This script can even perform different actions if the instance was preempted as opposed to shut down from something you did.
One nice benefit of Google preemptible VMs is the ability to attach local SSD drives and GPUs to the instances. This means you can get added extensibility and performance for the workload that you are running, while still saving money. You can also have preemptible instances in a managed instance group for high scalability when the instances are available. This can help you process more of your jobs at once when the preemptible virtual machines are able to run.
How to Use Google Preemptible VMs to Optimize Costs
Our customers who have the most cost-effective use of Google resources often mix Google preemptible VMs with other instance types based on the workloads. For instance, production systems that need to be up 24/7 can buy committed-use discounts for up to 57% savings on those servers. Non-production systems, like dev, test, QA, and staging, can use on-demand resources with schedules managed by ParkMyCloud to save 65%. Then, any batch workloads or non-urgent jobs can use Google preemptible VMs to run whenever available for up to 80% savings. Questions about optimizing cloud costs? We’re happy to help — email us or use the chat client on this page (staffed by real people, including me!).
Originally published at www.parkmycloud.com on May 16, 2018.