What is Object Storage?
Object storage is a flat data storage architecture that manages data as immutable objects, each with a unique identifier, metadata, and API access over HTTP. It is the model behind Amazon S3 and similar cloud storage services.
Object storage is a data storage architecture that manages data as discrete units called objects, rather than as files in a hierarchical directory tree or as blocks on a disk. Each object contains the data itself, configurable metadata, and a globally unique identifier. Objects are stored in a flat address space (a bucket or container) and accessed primarily through HTTP-based APIs.
Unlike file storage, which organizes data in a nested folder structure and uses POSIX semantics, object storage treats data as immutable: you cannot modify a portion of an object. Instead, you upload a new version of the entire object. This design simplifies scaling to exabytes of data and eliminates the complexity of filesystem lock management. The most widely deployed object storage API is Amazon S3, formalized in multiple RFCs and used by services like Google Cloud Storage, Azure Blob Storage, and self-hosted systems like MinIO or Ceph.
Object storage is the foundation of modern cloud-native applications, data lakes, backup archives, and content delivery. Its flat namespace and HTTP interface allow direct integration with web applications, content delivery networks, and distributed processing frameworks like Spark or Hadoop. However, object storage lacks the low latency and atomic rename operations of file or block storage, making it unsuitable for databases or live virtual machine disks.
Key facts
- Objects are immutable; updates replace the entire object.
- Access occurs over RESTful HTTP APIs, most commonly S3-compatible.
- Data is stored in a flat bucket namespace, not a directory hierarchy.
- Scales to exabytes and billions of objects without performance degradation.
- Supports rich, user-definable metadata per object.
How it works in practice
Related terms
References
More in Storage
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Erasure Coding
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File Storage
File storage exposes data as a hierarchical filesystem over network protocols like NFS and SMB, commonly delivered via network-attached storage (NAS) appliances for shared access.
Hot Storage
Hot storage is the default high-performance tier in object storage systems, optimized for low-latency access to frequently retrieved data.
iSCSI
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NFS
NFS (Network File System) is a distributed file system protocol originally developed by Sun Microsystems that allows a client to access files over a network as if they were local. It is widely used in Unix and Linux environments and runs over IP networks.
RAID
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RAID 0
A data storage method that splits data across two or more disks in stripes to improve read and write performance, but provides no fault tolerance.