Learn Ceph - History, Background & Why Choose Ceph

#Introduction

Welcome to the first episode of the Learn Ceph series! Before building a cluster, it's important to understand where Ceph comes from and why it's been adopted by so many large infrastructures. This episode covers Ceph's history, the background of the problems it aims to solve, and the concrete reasons why you should choose Ceph over other storage solutions.

Ceph isn't a product born overnight. It started as an academic research project and evolved into one of the most influential open-source storage platforms in the world. Understanding this history helps you understand the architectural decisions we'll encounter in the following episodes, such as why Ceph builds everything on top of RADOS.

By the end of this episode you'll have a clear argument about when, why, and how Ceph should be used — an important mental foundation before diving into the technical installation in episode 3.

#Ceph's History and Evolution

#The Beginning: Sage Weil's Thesis

Ceph began in 2006 as a research project by Sage Weil during his doctoral studies at the University of California, Santa Cruz. Its core design — a fully decentralized distributed storage system that eliminates single points of failure — was laid out in the paper "Ceph: A Scalable, High-Performance Distributed File System".

In 2010, Sage Weil founded Inktank to commercialize Ceph, and in 2014 Inktank was acquired by Red Hat. Since then Ceph has grown rapidly with strong community and vendor support, becoming part of the OpenStack and Kubernetes ecosystems.

#From CephFS to Unified Storage

Initially Ceph only offered a distributed file system (CephFS). Over time, three main interfaces emerged that made Ceph known as unified storage:

• RBD for block storage, adopted by OpenStack Cinder and Kubernetes CSI.
• CephFS for file storage with POSIX semantics.
• RGW for object storage compatible with S3 and Swift.

Its core philosophy: one cluster, three interfaces. Data is always stored in RADOS, while the layers above adapt the access method.

#Why Choose Ceph

#Unified Storage in a Single Cluster

Ceph's first advantage is its ability to present block, file, and object storage from the same cluster. Imagine a single set of nodes serving VM disks, a shared filesystem, and S3 buckets at the same time. This simplifies operations because you manage one system instead of three different products.

From a capacity perspective, different pools can share the same physical storage pool, so disk utilization is more efficient than separate storage silos.

#Scalability and Elimination of Single Points of Failure

Ceph is designed to scale out horizontally: add nodes, add capacity, with no downtime. Data is placed automatically by the CRUSH algorithm without needing a central index — every client can compute data locations on its own.

This architecture removes the single point of failure at the controller level. MON, MGR, and OSD are all designed for redundancy; the failure of one node doesn't bring down the cluster as long as quorum is maintained.

#Open Source and a Mature Ecosystem

Ceph is open-source software with a permissive license and is maintained by a large community. This means:

• No vendor lock-in and no licensing costs.
• Very complete official documentation at docs.ceph.com.
• Native integration with Kubernetes, OpenStack, and ecosystem tooling.

#Comparison with Other Solutions

#Traditional SAN/NAS

SAN and NAS use a central controller that handles all I/O. This model is easy to manage but is prone to bottlenecks and single points of failure at the controller, and it's hard to scale out beyond controller capacity. Ceph offers a scale-out alternative with a decentralized architecture.

#GlusterFS

GlusterFS is also an open-source distributed file system, but its main focus is only file storage. It doesn't provide unified block and object storage like Ceph does, and its data placement model is volume-based, simpler than CRUSH.

#Other Object Storage: Swift and MinIO

OpenStack Swift is a solid object storage system, but it doesn't unify block and file in a single system. MinIO is very popular for lightweight S3 deployments, but it doesn't offer RADOS as a common foundation for all three interfaces at once.

feature         Ceph        GlusterFS    SAN/NAS
block           yes         no           yes
file            yes         yes          yes
S3 object       yes         no           limited
scale out       horizontal  horizontal   limited

#Ceph's Main Use Cases

#Cloud Block Storage and Database Backends

Ceph RBD is a common choice for VM disks in OpenStack and Kubernetes, as well as a storage backend for databases, thanks to its support for snapshots, clones, and thin provisioning. RBD performance is sufficient for block I/O workloads that demand low latency.

#Enterprise File Services

CephFS is used for shared storage in applications that need POSIX semantics, such as home directories, CI build caches, and applications that can't use object storage. With active-active MDS, metadata throughput can scale.

#S3-Compatible Object Storage

RGW provides object storage with a compatible S3 API, suitable for backup, data lakes, media, and archives. Lifecycle features, versioning, and multi-site make it viable for global deployments.

ceph osd pool create demo 32
ceph osd pool ls

ceph osd pool create demo 32 creates a pool named demo with 32 placement groups — we'll dissect this syntax fully in episode 4.

#Conclusion

In this episode you've understood Ceph's journey from an academic project to a unified storage platform, its main advantages over SAN/NAS, GlusterFS, and Swift, and the use cases driving its adoption in the real world.

The key takeaways:

• Ceph was born in 2006 from Sage Weil's research and was matured by Red Hat.
• A single Ceph cluster provides block, file, and object storage at once.
• CRUSH places data without a central index, eliminating single points of failure.
• Compared to SAN/NAS and GlusterFS, Ceph excels in horizontal scalability and unification.
• Main use cases: cloud block storage, enterprise file services, and S3 object storage.

In the next episode, episode 2, we'll move into Ceph's core concepts and architecture — dissecting the core components MON, OSD, MDS, MGR, RGW, and RADOS as the foundation of all services, plus how the CRUSH map, pools, placement groups, and replication work. Understand episode 2 well, because the entire series stands on it!