Category Archives: Scality

Project COSI

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The S3 (Simple Storage Service) has become a de facto standard for accessing object storage. Many vendors claim 100% compatibility to S3, but from what I know, several file storage services integration and validation with the S3 have revealed otherwise. There are certain nuances that have derailed some of the more advanced integrations. I shall not reveal the ones that I know of, but let us use this thought as a basis of our discussion for Project COSI in this blog.

Project COSI high level architecture

What is Project COSI?

COSI stands for Container Object Storage Interface. It is still an alpha stage project in Kubernetes version 1.25 as of September 2022 whilst the latest version of Kubernetes today is version 1.26. To understand the objectives COSI, one must understand the journey and the challenges of persistent storage for containers and Kubernetes.

For me at least, there have been arduous arguments of provisioning a storage repository that keeps the data persistent (and permanent) after containers in a Kubernetes pod have stopped, or replicated to another cluster. And for now, many storage vendors in the industry have settled with the CSI (container storage interface) framework when it comes to data persistence using file-based and block-based storage. You can find a long list of CSI drivers here.

However, you would think that since object storage is the most native storage to containers and Kubernetes pods, there is already a consistent way to accessing object storage services. From the objectives set out by Project COSI, turns out that there isn’t a standard way to provision and accessing object storage as compared to the CSI framework for file-based and block-based storage. So the COSI objectives were set to:

  • Kubernetes Native – Use the Kubernetes API to provision, configure and manage buckets
  • Self Service – A clear delineation between administration and operations (DevOps) to enable self-service capability for DevOps personnel
  • Portability – Vendor neutrality enabled through portability across Kubernetes Clusters and across Object Storage vendors

Further details describing Project COSI can be found here at the Kubernetes site titled “Introducing COSI: Object Storage Management using Kubernetes API“.

Standardization equals technology adoption

Standardization means consistency, control, confidence. The higher the standardization across the storage and containerized apps industry, the higher the adoption of the technology. And given what I have heard from the industry over these few years, Kubernetes, to me, even till this day, is a platform and a framework that are filled and riddled with so many moving parts. Many of the components looks the same, feels the same, and sounds the same, but might not work out the same when deployed.

Therefore, the COSI standardization work is important and critical to grow this burgeoning segment, especially when we are rocketing towards disaggregation of computing service units, resources that be orchestrated to scale up or down at the execution of codes. Infrastructure-as-Code (IAC) is becoming a reality more and more with each passing day, and object storage is at the heart of this transformation for Kubernetes and containers.

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My dilemma of stateful storage marriage

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I should be a love match maker.

I have been spending much hours in the past few months, thinking of stateful data in stateful storage containers and how they would consummate with distributed applications containers and functions-as-a-service (aka serverless, aka Lambda). It still hasn’t made much sense, and I have not solved this problem yet. Although there were bits and pieces that coming together and the jigsaw looked well enough to give a cackled reply, what I have now is still not good enough for me. I am still searching for answers, better than the ones I have now.

The CAP theorem is in center of my mind. Distributed data, distributed states of data are on my mind. And by the looks of things, the computing world is heading towards containers and serverless computing too. Both distributed applications containers and serverless computing make a lot of sense. If we were to engage a whole new world of fog computing, edge computing, IoT, autonomous systems, AI, and other real-time computing, I would say that the future belongs to decentralization. Cloud Computing and having edge systems and devices getting back to the cloud for data is too slow. The latency of micro- or even nano-seconds is just not good enough. If we rely on the present methods to access the most relevant data, we are too late.

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Of Object Storage, Filesystems and Multi-Cloud

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Data storage silos everywhere. The early clarion call was to eliminate IT data storage silos by moving to the cloud. Fast forward to the present. Data storage silos are still everywhere, but this time, they are in the clouds. I blogged about this.

Object Storage was all the rage when it first started. AWS, with its S3 (Simple Storage Service) offering, started the cloud storage frenzy. Highly available, globally distributed, simple to access, and fitted superbly into the entire AWS ecosystem. Quickly, a smorgasbord of S3-compatible, S3-like object-based storage emerged. OpenStack Swift, HDS HCP, EMC Atmos, Cleversafe (which became IBM SpectrumScale), Inktank Ceph (which became RedHat Ceph), Bycast (acquired by NetApp to be StorageGrid), Quantum Lattus, Amplidata, and many more. For a period of a few years prior, it looked to me that the popularity of object storage with an S3 compatible front has overtaken distributed file systems.

What’s not to like? Object storage are distributed, they are metadata rich (at a certain structural level), they are immutable (hence secure from a certain point of view), and some even claim self-healing (depending on data protection policies). But one thing that object storage rarely touted dominance was high performance I/O. There were some cases, but they were either fronted by a file system (eg. NFSv4.1 with pNFS extensions), or using some host-based, SAN-client agent (eg. StorNext or Intel Lustre). Object-based storage, in its native form, has not been positioned as high performance I/O storage.

A few weeks ago, I read an article from Storage Soup, Dave Raffo. When I read it, it felt oxymoronic. SwiftStack was just nominated as a visionary in the Gartner Magic Quadrant for Distributed File Systems and Object Storage. But according to Dave’s article, Swiftstack did not want to be “associated” with object storage that much, even though Swiftstack’s technology underpinning was all object storage. Strange.

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