LinuxLX · Distributed Storage ConceptsObject vs block
Object and block storage tradeoffs - the right tool for the data
What you'll learn
- Distinguish object and block storage
- Choose the right storage for the workload
- Recognise when each is appropriate
- Design for mixed workloads
Prerequisites
Verified against Ubuntu 24.04 LTS · Debian 12 (Bookworm) · RHEL 9.x · Rocky Linux 9.x · AlmaLinux 9.x · Linux kernel 6.1 LTS / 6.6 LTS · systemd 255+ · OpenSSH 8.7p1 (RHEL 9) / 9.6p1 (Ubuntu 24.04) · nftables 1.0.x · chrony 4.x · Pacemaker 2.1.x · Corosync 3.1.x · 2026-08-09
Object storage (S3, RGW) and block storage (EBS, RBD, SAN) serve different access patterns. This lesson covers the tradeoffs and how to choose.
Block storage
Block storage exposes raw block devices:
- Use cases: databases, VM disks, file systems.
- Access: random read/write at byte level.
- Performance: low latency, high IOPS.
- Examples: AWS EBS, Ceph RBD, SAN, local disk.
Block storage requires a filesystem on top. The filesystem manages the data; the block device is the substrate.
Object storage
Object storage exposes objects via HTTP API:
- Use cases: media files, backups, large blobs, web assets.
- Access: PUT / GET / LIST.
- Performance: high throughput, higher latency.
- Examples: AWS S3, Ceph RGW, MinIO.
Object storage is essentially unlimited in size and has no directory hierarchy (use prefixes and metadata).
Trade-offs
| Property | Block | Object |
|---|---|---|
| Access | Block-level, random | HTTP API, key-based |
| Latency | Low (sub-ms) | Higher (10s of ms) |
| Throughput | High per IO, lower aggregate | Lower per IO, very high aggregate |
| Size | Limited per volume | Unlimited |
| Modification | In-place | Replace whole object |
| Consistency | Strong | Strong (for S3-compatible) |
| Use cases | DB, VM, FS | Media, backups, blobs |
Choose the right tool
| Data | Storage |
|---|---|
| Database | Block (EBS, RBD) |
| VM disk | Block (EBS, RBD) |
| Filesystem | Block + FS, or POSIX FS (CephFS, Gluster) |
| Media files | Object (S3) |
| Backups | Object (S3, with Object Lock) |
| Large blobs | Object (S3) |
| Logs | Object (S3) or block (depending on volume) |
Mixed workloads
Most production uses a mix:
- Block for databases and VM disks.
- Object for media, backups, and large files.
- POSIX FS for shared file access.
Ceph provides all three from one platform (RBD, RGW, CephFS). S3 + EBS + EFS for AWS.
Knowledge check
Knowledge check · 3 questions
Q1. Which is the right storage for a database?
Q2. Object storage is the right tool for backups.
Q3. Which of the following are valid object storage services? Select all that apply.
Passing score: 75%. Answers are checked in this browser.