Types of Storage Systems: Block, File, and Object Storage

Choosing the right data storage model is one of the most critical decisions in System Design.

This choice has a profound impact on a system’s performance, scalability, cost, and complexity. For any application, from a simple photo-sharing app to a large-scale enterprise database, the underlying storage strategy dictates how data is accessed, managed, and scaled.

Understanding these foundational models is essential for building robust and efficient distributed systems.

This lesson explores the three primary storage paradigms: block, file, and object storage. We will analyze their architectures, access patterns, and ideal use cases to equip us with the knowledge needed to select the appropriate solution for our next System Design interview or project.

Let's start with the block storage.

Block storage

Block storage is the lowest level of data storage and the foundation upon which other storage systems are often built.

It carves storage into fixed-size data chunks called blocks, each with a unique address. At this level, the system’s role is purely to store and retrieve these blocks; it has no awareness of higher-level concepts, such as files or folders.

To make this storage usable, blocks are organized into logical units called volumes.

An operating system on a server connects to these volumes and formats them with a file system like ext4A widely used Linux file system that organizes and manages data efficiently on disks with strong support for large files and journaling for reliability. or NTFSThe primary Windows file system designed for security, reliability, and support of advanced features like permissions, encryption, and large file sizes. to manage data access. Block storage’s primary advantages are its high performance and low latency. Since data is accessed directly at the block level, it is ideal for applications requiring frequent, granular read and write operations.

The illustration below shows this direct-access architecture, where a Worker representing a compute resource, such as a server or application, can access any data block simply by using its unique address.

Block storage systems rely on high-speed communication protocols and dedicated infrastructure to deliver consistently low latency and high throughput.

These systems enable direct, efficient data exchange between servers and storage devices. Common protocols include iSCSI, which transmits block data over IP networks, and Fibre Channel, which provides high-speed connectivity through specialized networking hardware.

By minimizing overhead and optimizing ...