Object Storage vs Block Storage: Key Differences

The core difference: blocks vs objects

Block storage carves a volume into fixed-size blocks (typically 512 bytes to 4 KB) that the operating system stitches together into a filesystem. It looks and behaves like a raw disk — you mount it, format it as ext4, XFS, or NTFS, and read or write individual blocks at very low latency. This is the storage your VPS boot disk and database run on.

Object storage takes a completely different approach. Each file becomes a self-contained 'object' bundled with its metadata and a unique ID, stored in a flat namespace called a bucket. There's no filesystem and no in-place editing — you GET, PUT, and DELETE whole objects over an HTTP API, usually the S3 API. That trade — losing random block-level writes — is exactly what lets object storage scale to billions of files and span many machines.

How you access each one

Block storage is attached to a single server at a time. The kernel sees a device like /dev/sdb, you put a filesystem on it, and applications read and write as if it were a local SSD. Because only one host owns the volume, latency is low (often sub-millisecond on NVMe) but sharing is hard.

Object storage is reached over the network by any client that can speak HTTP and authenticate. A request looks like a signed GET to https://endpoint/bucket/photos/2026/cat.jpg. That makes objects trivially shareable across servers, regions, apps, and CDNs — but every operation pays network round-trip latency (tens of milliseconds), so it's wrong for the hot path of a database.

• Block: mount once, low latency, single-host, POSIX filesystem on top
• Object: HTTP/S3 API, high concurrency, accessible from anywhere, metadata-rich

Performance, scale, and durability

Block volumes deliver consistent IOPS and latency, which is why transactional databases, OS disks, and any workload doing small random reads/writes belong there. The ceiling is the volume size and the single instance it's attached to — typically up to a few terabytes per volume.

Object storage trades per-request speed for near-limitless scale and built-in redundancy. Providers commonly advertise 11 nines of durability (99.999999999%) by replicating or erasure-coding each object across multiple disks and nodes, so a failed drive never loses your data. A single bucket can hold petabytes and billions of objects without you provisioning anything. Throughput for large sequential transfers is excellent; latency per tiny request is not.

What it costs — and the egress trap

Block storage is usually priced per provisioned GB per month (roughly $0.08–$0.15/GB) whether or not you fill it, plus sometimes a charge for higher IOPS tiers. You pay for the capacity you allocate.

Object storage is billed for what you actually store, often per terabyte — NordicVentures object storage starts at $5/TB/mo. The catch with many providers is hidden costs: egress (downloading your own data) at $0.05–$0.09/GB and per-request API fees that can inflate a bill 30–50% over the advertised storage rate. When you compare quotes, model your real egress and request volume, not just the headline per-GB price. NordicVentures charges zero egress and zero API fees, so the rate on the page is the rate you pay.

Which one should you use?

Reach for block storage when an application needs a real filesystem or low-latency random I/O: database data directories, VM boot disks, search indexes, or any single-writer workload. Reach for object storage when you have lots of unstructured files that are written once and read many times: backups and snapshots, user uploads, images and video, log archives, data-lake datasets, and static assets served through a CDN.

Most real architectures use both. A typical web app runs its Postgres on a fast NVMe block volume, then offloads user-uploaded images, nightly database dumps, and static media to an S3-compatible bucket — keeping the expensive low-latency disk small and pushing bulk, rarely-changing data to cheap, durable object storage.

• Pick block: databases, boot disks, low-latency random I/O, single writer
• Pick object: backups, media, uploads, logs, static assets, data lakes
• Use both: small fast block volume + large cheap object bucket

Moving forward

If your block volumes are filling up with backups, media, or archives, that's the classic signal to move that data to object storage — you'll cut cost and gain durability without touching your database disk. The migration is usually a matter of pointing your app or backup tool at an S3 endpoint.

NordicVentures object storage is fully S3-compatible, so existing tools and SDKs work unchanged, with EU and US regions, 11 nines durability, zero egress fees, and free migration help. If you're weighing where your bulk data should live, explore object storage to see plans and pricing.