Block vs. Object vs. File Storage

Your data has to live somewhere. Over decades of computing, we've settled on three fundamentally different answers to "how should storage work?"—and each answer reflects a different set of priorities.

The Core Tradeoff

Storage can optimize for three things, but not all at once:

• Performance: How fast can I read and write?
• Scalability: How much can I store?
• Accessibility: How easily can multiple things access this data?

Block storage maximizes performance. Object storage maximizes scalability. File storage maximizes accessibility. Everything else follows from these choices.

Block Storage: The Useful Lie

Block storage presents itself as a local disk. Your server formats it, mounts it, and treats it exactly like a hard drive plugged directly into the machine. The fact that it's actually sitting in a data center, accessed over a network via iSCSI or Fibre Channel—your server doesn't know or care.

This lie is useful because databases and operating systems were built assuming local disks. They expect to read block 47,392 and get an answer in microseconds. They expect writes to happen in order. They expect the disk to be theirs alone.

Block storage delivers:

• Latency measured in milliseconds or less
• The ability to run any filesystem (ext4, NTFS, ZFS)
• Consistent, predictable performance
• Complete control over how data is organized on disk

The cost of this lie is significant. Block storage is expensive—you're paying for dedicated, high-performance infrastructure. It typically attaches to one server at a time. And managing it at scale requires real expertise.

Use block storage for: Databases. Virtual machine disks. Anything that was designed assuming a local drive and can't be convinced otherwise.

Cloud examples: AWS EBS, Azure Managed Disks, Google Persistent Disks

Object Storage: Honest About Being Remote

Object storage doesn't pretend to be a disk. It's a web service. You PUT objects in, you GET objects out. Every object has a unique key, lives in a bucket, and carries metadata describing what it is.

This honesty enables something block storage can't achieve: virtually unlimited scale at remarkably low cost. When you're not pretending to be a local disk, you can spread data across thousands of machines, replicate it globally, and charge pennies per gigabyte.

Object storage delivers:

• Petabytes to exabytes of capacity
• Built-in redundancy (your data survives hardware failures)
• HTTP access from anywhere in the world
• Rich metadata for organization and search
• Costs that don't make your CFO cry

The tradeoff is latency. Every request is an HTTP round-trip. You can't open a file, seek to byte 1,000,000, and read 50 bytes—you fetch the whole object or use range requests. Traditional applications expecting filesystem semantics won't work without modification.

Use object storage for: Backups. Archives. Images and videos. Data lakes. Anything where you're storing lots of data, accessing it via applications, and cost matters more than milliseconds.

Cloud examples: AWS S3, Azure Blob Storage, Google Cloud Storage

File Storage: The Shared Middle Ground

File storage is what most people think of when they think "storage." Folders containing files. A hierarchy you can browse. Multiple users opening the same document.

Under the hood, file storage is a server that speaks NFS (for Linux/Unix) or SMB (for Windows). Clients connect over the network and interact with files using the same operations they'd use locally: open, read, write, close. The network is visible—you're mounting a remote share—but the experience feels familiar.

File storage delivers:

• A mental model everyone already understands
• Multiple clients accessing the same files simultaneously
• Compatibility with applications expecting filesystem access
• Hierarchical organization that makes sense to humans

The tradeoffs are moderate in every dimension. File storage is more expensive than object storage but cheaper than block. It scales better than block but not as well as object. Performance depends heavily on the network and the file server's capacity.

Use file storage for: Shared drives. Home directories. Content management. Development environments. Anywhere humans need to browse and collaborate on files, or applications need concurrent access to the same data.

Cloud examples: AWS EFS, Azure Files, Google Cloud Filestore

The Decision in Practice

The question isn't "which storage type is best?" It's "what does my data need?"

Your database needs block storage. It was written assuming a local disk. It issues thousands of small random reads per second. It needs consistent sub-millisecond latency. Don't fight this—give it block storage and move on.

Your user uploads need object storage. Profile pictures. Uploaded documents. Media files. These are write-once, read-many. They need to scale indefinitely. They're accessed via your application, not by users browsing a filesystem. Object storage is perfect.

Your shared documents need file storage. The marketing team's assets. The engineering team's shared configs. Anything where multiple people or systems need to access the same files with familiar tools.

Most real systems use all three. The database runs on block storage. User content lives in object storage. Shared files sit on file storage. Each type handles what it's good at.

Hybrid Patterns

Block + Object: Run your database on block storage for performance, but back it up to object storage for cost-effective retention. This is nearly universal.

File Gateway to Object: Can't modify your application to use object storage APIs? Tools like AWS Storage Gateway present S3 buckets as NFS/SMB shares. Your legacy app sees files; underneath, it's objects.

Automatic Tiering: Move data between storage types based on access patterns. Hot data stays on fast (expensive) storage; cold data migrates to cheap object storage automatically.

What the Future Looks Like

The lines are blurring. Cloud providers build file storage on object storage infrastructure. Managed databases abstract away whether they're using block, file, or object storage internally. New applications are designed from the start to use object storage APIs.

But the fundamental tradeoffs remain. You can optimize for performance, scalability, or accessibility—pick two. Block storage, object storage, and file storage are just three points on that triangle, each making different sacrifices.

Understand what your data needs, and the choice becomes obvious.