Softwr

File Storage · head to head

Ceph vs Seldon

Ceph logo

Ceph

File Storage

Open source distributed storage providing object, block and file from one cluster

From
Free
Rated
-
Full reviewWebsite
Seldon logo

Seldon

Machine Learning

Kubernetes model serving whose current version is licensed under the Business Source Licence

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Ceph ceph assumes an operator who understands placement groups, CRUSH rules and recovery tuning, so organisations without dedicated storage staff routinely end up with a cluster that works until the first failure and then does not.; Seldon seldon Core v2 is under the Business Source Licence rather than Apache 2.0, so production use requires a commercial agreement, and a team that evaluated it believing it was open source discovers the licence is the blocker exactly when the project is ready to ship.
  • They diverge on capability: Ceph covers RADOS object store, Seldon covers Kubernetes custom resources.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Ceph and Seldon actually diverge.

Attributes where Ceph and Seldon differ
AttributeCephSeldon
Pricing modelOpen source, no licence feefreemium
CategoryFile StorageMachine Learning
FoundedUnknown2014

Identical on both: starting price (Free), free tier (Yes), platforms (Linux), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Ceph

  • RADOS object store
  • RADOS Gateway
  • RBD block devices
  • CephFS
  • CRUSH placement
  • Erasure coded pools

Only in Seldon

  • Kubernetes custom resources
  • Inference graphs
  • Traffic strategies
  • Open Inference Protocol
  • Alibi Explain
  • Alibi Detect
  • Kafka-backed pipelines in v2
  • Commercial control plane

What people use each for

The jobs each tool is most often brought in to do.

Ceph

  • Backing a private cloud where virtual machine disks, shared filesystems and an S3 endpoint all need the same hardwarenot Seldon
  • Growing past the point where a proprietary array upgrade costs more than a rack of commodity serversnot Seldon
  • Research and media environments with petabytes of data and staff who can operate storagenot Seldon
  • Providing an S3 endpoint on premises with multi site replication under your own controlnot Seldon

Seldon

  • Serving an ensemble or a multi-stage inference path as one versioned deployment rather than as a chain of separate servicesnot Ceph
  • Running genuine production experiments where a share of live traffic goes to a candidate model and the results are comparednot Ceph
  • Regulated environments needing explanations and drift monitoring attached to the served model rather than bolted on laternot Ceph
  • Organisations with an established Kubernetes platform team who want serving expressed as manifests under existing deployment controlsnot Ceph

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Ceph

  • Ceph assumes an operator who understands placement groups, CRUSH rules and recovery tuning, so organisations without dedicated storage staff routinely end up with a cluster that works until the first failure and then does not.
  • Small clusters are inefficient: three way replication means a third of raw capacity is usable, and erasure coding needs enough failure domains to be safe, so the economics only work above a certain size.
  • Recovery and rebalancing generate heavy internal traffic, so a failed disk can degrade client latency across the cluster unless backfill is throttled correctly beforehand.
  • Upgrades must follow a strict daemon order across monitors, managers, OSDs and gateways, and a mistake in that order on a live cluster is difficult to reverse.
  • Because it is self hosted, every byte served to the internet is transit you pay for on your own links, so the free licence does not mean free egress and bandwidth planning becomes your problem rather than the providers.

Seldon

  • Seldon Core v2 is under the Business Source Licence rather than Apache 2.0, so production use requires a commercial agreement, and a team that evaluated it believing it was open source discovers the licence is the blocker exactly when the project is ready to ship.
  • Core v1 remains Apache 2.0 but is in maintenance, so taking the free route means running software that receives no new development while the architecture it belongs to moves on without it.
  • Version 2 is a different system rather than a newer release, with different custom resources, a scheduler component and a Kafka-based pipeline model, so migrating from v1 is a re-implementation of every deployment manifest rather than an upgrade.
  • Kafka is a dependency for v2 pipelines, so an organisation that does not already operate it takes on a distributed log with its own storage, retention, rebalancing and failure modes purely in order to serve models.
  • Everything assumes Kubernetes fluency and the failure modes are Kubernetes failure modes, custom resource version mismatches, an operator that will not reconcile, admission webhooks and resource limits terminating an inference pod mid-request, so it needs a platform engineer rather than a data scientist.

Pricing, plan by plan

Ceph

Free
  • CephFree
    • Full functionality, no capacity limit
    • Object, block and file interfaces
    • Community support via mailing list and Slack

Seldon

Free
  • Seldon CoreFree
    • Open source
    • Kubernetes deployment
    • Model serving
  • Seldon DeployFree
    • Enterprise features
    • GUI
    • Monitoring

Which should you pick?

Choose Ceph if

  • You need rados object store.
  • You want to start without paying.
  • You work on Linux.
  • You also want rados gateway.
Ceph review

Choose Seldon if

  • You need kubernetes custom resources.
  • You want to start without paying.
  • You work on Linux.
  • You also want inference graphs.
Seldon review

Questions people ask

Is Ceph or Seldon better?
Neither clearly leads. Ceph starts at Free and Seldon at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Ceph or Seldon?
Ceph starts at Free and Seldon at Free.
Does Ceph or Seldon run on more platforms?
Both run on Linux, so platform support will not decide this one for you.
Can I use Ceph for free?
Both have a free tier, so you can try either at no cost before committing.
What is Ceph best used for?
Ceph is most often used for backing a private cloud where virtual machine disks, shared filesystems and an s3 endpoint all need the same hardware, growing past the point where a proprietary array upgrade costs more than a rack of commodity servers, research and media environments with petabytes of data and staff who can operate storage, providing an s3 endpoint on premises with multi site replication under your own control. Of those, backing a private cloud where virtual machine disks, shared filesystems and an s3 endpoint all need the same hardware and growing past the point where a proprietary array upgrade costs more than a rack of commodity servers are not what Seldon is typically brought in for.
What can Ceph do that Seldon cannot?
Ceph covers RADOS object store, RADOS Gateway, RBD block devices, CephFS. Seldon covers Kubernetes custom resources, Inference graphs, Traffic strategies, Open Inference Protocol.

Answered from the vendors’ own pages

Ceph: How many nodes do I need to start?

Three is the practical minimum for a replicated cluster with real fault tolerance, and most production advice starts at five once you account for maintenance windows.

Seldon: Is Seldon open source?

Partly, and this is the thing to check before you build on it. Core v1 is Apache 2.0 but in maintenance. Core v2 was moved to the Business Source Licence in 2024, which allows evaluation but not unlicensed production use. Verify the current licence of each component you intend to run, including MLServer and the Alibi libraries.

Ceph: Is it faster than a SAN?

Not on single stream latency. It wins on aggregate throughput and on growing without a forklift upgrade, which is a different property from raw speed.

Seldon: What is the difference between v1 and v2?

Architecture, not just version number. v2 introduces a scheduler, a different set of custom resources and Kafka-backed pipelines. Manifests, mental model and operations all change, so treat a move as a project.

Ceph: Can I buy support?

Yes. IBM sells IBM Storage Ceph and SUSE and others have offered supported builds; the upstream project itself is free.

Seldon: Do I need Kubernetes?

Yes. It is a Kubernetes-native system and there is no meaningful deployment without a cluster and someone competent to run it.

Ceph: Should I use it just for S3?

If object is all you need, a dedicated object store is simpler to run. Ceph earns its complexity when you need block and file as well.

Seldon: What is MLServer?

Seldon's Python inference server implementing the Open Inference Protocol, usable inside Seldon deployments or on its own. Check its current licence alongside Core's, since the company has moved projects onto the Business Source Licence.

Seldon: Do I have to run Kafka?

For v2 pipelines, yes. If you only need single models served, that dependency is a large amount of infrastructure for the benefit, and a simpler serving layer may be the better answer.

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