Object Storage Ledger Methodology: How Every Score Is Built

Part of the Object Storage Ledger (edition 2026-10-16). The results are in the overview and the product reports. The Ledger uses the same method as the VM Platform Ledger; this page covers what is specific to S3-compatible object storage you run yourself.

Who this is for

Teams that need an S3 endpoint on their own hardware or cloud instances: an immutable target for Veeam, Commvault, Rubrik or Proxmox Backup Server, a data lake for analytics or AI, storage for Kubernetes applications, or a multi-tenant service. Homelab readers choosing what replaces MinIO Community Edition are served by the same scores through the edge lens. No vendor was briefed on, paid for or reviewed any score.

What is in scope

A product is included when it shipped a release in the last 12 months, has public documentation or release notes, is available outside one country or one hardware line (hardware-bound products are included and flagged), and offers an S3 API with versioning and multipart upload. Object lock support and its modes are recorded for every entry because immutability drives most purchases in this category.

Cloud object storage services (Amazon S3, Wasabi, Backblaze B2, Cloudflare R2, Hetzner, OVHcloud, Scaleway, Storj) are out of the Ledger; their prices and egress terms belong to a tracker. Garage, Apache Ozone and WEKA's S3 front end are out because versioning or object lock could not be found in their documentation; they are re-tested each edition. LeoFS, Riak CS and OpenIO have stopped releasing and appear as milestones. MinIO Community Edition is kept as a flagged end-of-life entry because it is still widely deployed, and its report dates each step of the wind-down from May 2025 to the repository archive in April 2026.

Engines, products and platforms

Ceph RGW is the engine inside IBM Storage Ceph and Red Hat OpenShift Data Foundation, and NooBaa the engine inside ODF's multicloud gateway; Versity S3 Gateway and Zenko CloudServer are standalone gateway engines whose durability comes from the backend they front. Engines carry no commercial risk score. Nutanix Objects is scored as storage inside a platform; FlashBlade, VAST Data and Qumulo are file-first platforms with a native S3 API and are flagged as such; ObjectScale, StorageGRID, ActiveScale and HCP are flagged where the software is sold mainly with the vendor's hardware.

Capability: ten domains, scored since 2015

Domain	Weight	What a 3 (solid) means	What a 5 (reference) means
S3 API fidelity	15	Versioning, multipart, lifecycle expiration, tagging, presigned URLs, bucket policies and server-side encryption that work with the common SDKs and tools	Plus STS and IAM-compatible APIs, event notifications, conditional writes and checksums, S3 Select, Tables or Express, a published compatibility matrix, AWS additions tracked within about a year
Immutability and compliance	12	Object lock in governance and compliance modes with legal hold and default retention, and at least one backup-vendor validation	Plus an independent compliance assessment, several backup-vendor validations, protection from admin deletion, retention preserved across replicas
Durability and resilience	12	Erasure coding or three-way replication, bitrot detection with healing, node failure tolerated, async replication to a second site	Plus per-bucket protection policy, active-active or stretched multi-site, rack and site failure domains, tested rebuild behaviour
Performance and scale	12	Scales out across dozens of nodes, hundreds of millions of objects, documented sizing	Billions of objects, S3 over RDMA or GPUDirect GA, metadata that scales independently of capacity, independent benchmark evidence
Deployment freedom	10	Bare metal and VMs on commodity x86, single node and cluster, container images	Plus a Kubernetes operator, Arm, edge single node, air-gapped install, software-only with no certified hardware, public cloud
Security and multi-tenancy	10	IAM users and policies, STS, OIDC or LDAP, TLS, encryption with an external KMS, audit logs	Plus tenant isolation with quotas and QoS, SAML and OIDC federation, KMIP or HSM, FIPS-validated crypto, MFA delete, a public advisory process with a clean recent record
Operations	10	A web console, Prometheus metrics, rolling upgrades, CLI and API, a documented upgrade path	Plus Terraform and Ansible, fleet management for many clusters, non-disruptive expansion and decommission, published long-term support
Protocols beyond S3	7	One further protocol GA (NFS, SMB, Swift, Azure Blob or HDFS)	NFS and SMB with locking, HDFS, Azure Blob or GCS compatibility, a native Iceberg catalog, all GA
Lifecycle and tiering	7	ILM rules for expiration and transition between storage classes, tiering to another S3 target	Plus tape or archive classes with restore, policy by tag, size and age, quotas and chargeback reporting
Ecosystem and openness	5	A documented S3 API with working SDKs and tools, a public community or partner channel	An open-source licence without field-of-use limits, active outside contributors, broad third-party integrations, no redistribution limits

Each domain is scored 0 to 5 at the end of 2015, 2019 and 2022 and today, against the same anchors every year. Only generally available capability counts; previews count half a step at most. Object lock is a 2018 feature of the S3 API itself, so the immutability domain is near zero for every product before then. Licence terms are scored in commercial risk and lock-in, not in the ecosystem domain, so a licence change counts once.

The other dimensions

Credibility (out of 25): release cadence, roadmap transparency, the say-do record (what was announced in 2023 to 2026 and whether it shipped), velocity and lifecycle stability. Vendors who keep release notes behind a login cannot score above 2 on roadmap transparency in a public-record Ledger.
Commercial risk (out of 25, lower is better): price and licence changes since 2023 (the MinIO community wind-down and AIStor's free-tier terms, per-TB minimums, appliance-only sales), purchase constraints, channel access, owner stability (Red Hat storage moving to IBM, the Pure Storage rename to Everpure, Quantum's management change) and the cost of staying supported.
Sustainability risk (out of 25, lower is better): used instead for community projects that nobody sells.
Technical lock-in (out of 25, lower is better): on-disk layout and whether data can be read without the product, the export path (S3 to S3 replication helps every product here), coupling to a platform or appliance, and skills.
Integrator fit (out of 20): partner programme, multi-tenancy and self-service, API and infrastructure-as-code depth, skills and certification.
AI leverage (out of 20): AI workload support (GPUDirect, RDMA, AI data lake positioning), bundled AI platforms, AI-assisted operations, and official agent interfaces such as MCP servers.

The Ledger Index

A single number out of 100: capability 35, credibility 20, buyer safety 20, AI leverage 10, integrator fit 10 and momentum 5 (capability gained since the end of 2022). Buyer safety is one minus the sum of commercial (or sustainability) risk and lock-in, divided by 50; for engines it uses lock-in alone. The Index is shown only from 2023.

Evidence and calibration

Every score comes from the public record: release notes, documentation and compatibility pages, licence and pricing pages, lifecycle pages, GitHub repositories and press releases. Reports carry an evidence grade (A primary sources, B secondary, C inferred) and end with open questions. Several enterprise vendors blocked automated reading or keep documentation behind a login, so their reports carry lower grades and more open questions; the open-source products and MinIO are the best evidenced. Corrections are welcome from anyone, vendors included, with a public source, and are logged in the next edition. The Ledger is refreshed twice a year, in March and October.