Object Storage vs Block Storage: What's the Difference?

When you move to the cloud, you quickly encounter two distinct storage paradigms: object storage and block storage. They look similar on the surface — both store data — but they are architecturally different and optimised for very different use cases. Choosing the wrong type can lead to poor performance, unnecessary cost, or both.

Block Storage: The Virtual Hard Drive

Block storage works like a traditional hard drive. Data is stored in fixed-size blocks, and the storage volume is attached directly to a server as a mountable disk. Your operating system sees it as a local drive and can format it with any filesystem — ext4, XFS, NTFS, and so on.

This makes block storage ideal for workloads that require low-latency, high-throughput I/O: databases, virtual machine images, and application data that changes frequently. The trade-off is that block volumes are typically attached to a single server at a time and are priced per gigabyte provisioned, regardless of how much you actually use.

Object Storage: Infinitely Scalable, HTTP-Accessible

Object storage treats data as discrete objects — each with its own unique identifier, metadata, and the data payload itself. Objects are stored in flat namespaces called buckets and accessed via HTTP APIs (most commonly the S3-compatible API). There is no filesystem, no mounting, and no concept of directories in the traditional sense.

Object storage scales to virtually unlimited capacity and is priced per gigabyte stored and per request. It is the right choice for static assets (images, videos, documents), backups, data archives, and any content that is written once and read many times. The HTTP-native access model also makes it trivially easy to serve content directly to end users via a CDN.

Choosing the Right Storage Type

Use block storage when your application needs a persistent, low-latency disk — for example, a MySQL database, a Redis instance, or a file server. Use object storage for everything else: user-uploaded files, static website assets, log archives, and backups.

Many modern architectures use both: a block volume for the database and application data, and object storage for media files and backups. This combination gives you the performance where you need it and the cost efficiency where you do not.