A Disk Usage Alert Led Me Down the OpenStack Rabbit Hole

Nasim Hossain Rabbi — Mon, 27 Jul 2026 05:50:30 +0000

It Started With a Disk Usage Alert

While going through our monitoring dashboards, I noticed that one of our backup object storage servers had been experiencing high disk usage for quite some time. Since the issue had remained unresolved, I decided to take ownership of the investigation.

Our existing disaster recovery setup consisted of two independent single-node OpenStack Swift deployments. Instead of native replication, data was periodically copied from the primary server to the backup server using a custom synchronization process, where objects were downloaded, staged on the backup server, and then uploaded back into its own Swift instance.

After reviewing the existing architecture and previous discussions, I found that several approaches had already been proposed. These included using rsync or rclone for more efficient synchronization, inotifywait for near real-time replication, and even introducing a Virtual IP (VIP) with Keepalived to improve failover. Each proposal addressed a specific operational challenge and aimed to improve disaster recovery.

The more I read, however, the more I realized that we were continuously adding new components and operational logic around keeping two completely independent object storage systems in sync.

Rather than deciding which approach to implement, I stepped back and asked a simpler question:

There had to be a simpler way!

That question eventually led me to explore OpenStack Swift's native clustered architecture, where many of these challenges are already solved by design.

Discovering OpenStack Swift

While searching for a simpler approach, I discovered that the architecture already includes concepts like distributed storage, replication, fault tolerance, and self-healing clusters.

In other words, many of the problems we were trying to solve manually had already been solved years ago.

Instead of copying files between independent servers and building increasingly complex synchronization logic, Swift is designed to run as a cluster where data is automatically replicated across storage nodes.

The more I read, the more one question kept coming back:

Why weren't we using the architecture it was originally designed for?

I don't know the answer. Every organization has historical decisions, constraints, deadlines, and trade-offs.

But discovering the intended architecture was a genuine "wait... this already exists?" moment.

That Rabbit Hole Became OpenStack

Naturally, curiosity won.

What started as learning about OpenStack Swift quickly turned into learning about OpenStack itself.

That's when I realized Swift is just one service in a much larger ecosystem.

OpenStack isn't simply an object storage solution. It's an open-source cloud platform that provides the building blocks needed to build your own private or public cloud, much like the services offered by AWS or Azure.

Many of its core projects have direct counterparts in the public cloud world:

OpenStack	Purpose	AWS Equivalent	Azure Equivalent
Nova	Virtual machines	Amazon EC2	Azure Virtual Machines
Neutron	Networking	Amazon VPC	Azure Virtual Network
Swift	Object storage	Amazon S3	Azure Blob Storage
Cinder	Block storage	Amazon EBS	Azure Managed Disks
Keystone	Identity & access management	AWS IAM	Microsoft Entra ID (Azure AD)
Horizon	Web management dashboard	AWS Management Console	Azure Portal
Heat	Infrastructure as Code	AWS CloudFormation	Azure Resource Manager (ARM)

OpenStack vs Public Clouds

One realization that helped everything click was understanding that OpenStack isn't competing with AWS or Azure in the traditional sense.

AWS and Azure are cloud providers. You consume their services.

OpenStack is a cloud platform. You deploy and operate it yourself.

Think of it this way:

Public Cloud	OpenStack
Rent infrastructure from a provider	Build and operate your own cloud
Provider manages the platform	You manage the platform
Pay as you go	Run on your own hardware
Best for public cloud workloads	Best for private, hybrid, or sovereign clouds

Once I looked at it from that perspective, the similarities between the services made much more sense. Nova isn't trying to replace EC2 as a business. It's providing the compute building block that lets you build a cloud platform with capabilities similar to what EC2 offers.

A Surprisingly Interesting Origin Story

The story behind OpenStack is just as interesting as the technology itself.

OpenStack was launched in 2010 through a collaboration between NASA and Rackspace. Yes, that NASA.

At the time, cloud computing was taking off, with providers like AWS leading the market. Instead of building another proprietary cloud, NASA and Rackspace set out to create an open-source cloud platform that anyone could deploy, modify, and contribute to.

The project began by combining NASA's Nova compute project with Rackspace's object storage technology. Over the years, it grew into one of the world's largest open-source infrastructure projects, supported by thousands of contributors and hundreds of organizations.

Today, OpenStack powers private and public clouds worldwide and is governed by the OpenInfra Foundation, now part of the Linux Foundation, continuing its mission of making cloud infrastructure open and accessible.

The Best Part

This whole journey started because of a disk usage alert.

I wasn't trying to learn about cloud architecture.

I wasn't researching OpenStack.

I certainly wasn't planning to spend hours reading about distributed object storage.

I was simply following a problem.

Sometimes that's how the best learning happens.

You pull on one thread, and suddenly you're exploring an entire ecosystem that has been quietly solving problems for more than a decade.

What's Next?

I'm planning to explore more of OpenStack over the coming weeks, especially how its different services work together to build a complete cloud platform.

If you've never looked into it before, I'd highly recommend spending some time exploring its projects and architecture.

Who knows?

You might start by investigating a simple monitoring alert and end up learning how an entire cloud platform is built.

Just be warned: building your own cloud sounds surprisingly achievable right up until you realize you're about to recreate a small part of AWS in your spare time. That's usually when you gain a whole new level of respect for the engineers who build and operate these systems every day.

Sometimes the best learning doesn't start with a tutorial. It starts with a production issue and a bit of curiosity. Happy exploring!

DEV Community: Nasim Hossain Rabbi