When it comes to cloud-native open-source projects, Kubernetes gets a lot of press. Why wouldn’t it? This container orchestration platform has revolutionized application development, deployment, and scaling. While the ability to quickly scale services up and down is one of Kubernetes’ top-selling points, managing sustained storage in this dynamic environment can be quite challenging.
How often were you moving an application between cloud platforms, but couldn’t move the data with its containers? Have you ever retired pods or containers only to find that the data within them has also been deleted? If so, you know the storage management challenges for Kubernetes. In this article, I’ll introduce you to the top five open-source cloud-native storage vendors.
First, let’s discover the multiple benefits of open source storage solutions.
Why Do You Need Open Source Storage for Kubernetes?
Unlike traditional proprietary, vendor-centric IT tools, the cloud-native ecosystem is all about community-driven open-source projects. That also applies to storage. Powerful open-source tooling makes managing persistent data with Kubernetes possible, and even easy!
As you delete a container or pod, you lose its data with it. That’s a big challenge, especially since stateful applications need persistent data. Open-source storage projects are well-integrated with Kubernetes, and the entire community actively develops them. They’re purpose-built for containerized applications, and can be used irrespective of where you run your Kubernetes–on-premises or in any cloud platform.
Storage Has Its Challenges
Kubernetes storage is completely different from traditional storage management. That’s because it includes new terminology and concepts, and new practices to manage storage. The data persistence concept mentioned above is something that we need to understand first. Then, we also have components like Persistent Volumes (PVs) and Persistent Volume Claims (PVCs). These are storage pieces in a Kubernetes cluster.
Now let’s take a look at the top 5 open source storage solutions that you can use as part of your business.
5 Open Source Storage Kubernetes Projects
The next challenge after understanding the nomenclature is to create a cohesive storage management platform through integrating open-source tools. That’s when you need to be aware of the top open source Kubernetes storage projects. Let’s now dive into them to see which ones suit your needs.
OpenEBS is a leading and easy-to-use open-source project that offers storage solutions for Kubernetes. It uses a cloud-native storage solution category called Container Attached Storage (CAS). It also creates and manages volumes within your Kubernetes environment. That means each storage volume has a specific pod and a set of replica pods. These are managed and deployed like any other container in Kubernetes.
The project itself is deployed as a set of containers on Kubernetes. It’s built completely in userspace which makes it highly portable to run across any OS/platform. OpenEBS replicates data across multiple nodes. That means any node failure would only impact volume replicas on that particular node. The project also creates an abstraction layer between the application and the underlying cloud service provider. That simplifies the data migration process across different vendors. It also eliminates vendor lock-in issues.
In September last year, OpenEBS released its latest version, OpenEBS 3.0. It included several new features and enhancements. It also introduced improvements to the existing LocalPV flavors and new LocalPV types. This new version also includes an OpenEBS dashboard (a Grafana and Prometheus blend) and a dynamic NFS provisioner.
The Node Disk Manager also underwent some changes. It saw a few fixes, like detecting filesystem changes, adding an extendable API service, adding reservation tags to devices, and more. What’s more, this latest OpenEBS version contains support for installation in air-gapped environments. It also adds enhanced documentation and troubleshooting guides for each engine located in its engine repositories.
Another very popular storage solution, Rook, is a community-driven project. It supports quite a wide range of storage solutions to integrate with the Kubernetes environment. It transforms storage volumes into self-scaling and self-managing storage systems that can heal themselves. Rook can orchestrate many storage solutions. That allows users to select from several different storage providers, depending on their workflow and application. That way It can efficiently distribute and replicate data to minimize loss.
Rook supports third-party monitoring tools. It also provides cluster security, scaling, and resource management in a single place. Through resource management, automation deployment, and scaling, Rook makes it easier for the cluster/admin to oversee storage frameworks.
In its latest version release, Rook’s secrets and config map now has a finalizer. That blocks accidental deletion and gives admins time to backup and restore these resources. That’s a useful feature, since the secrets and config map is one of Rook’s critical resources. The team has introduced new tools to set up application mirroring and perform fail-over and fail-back for applications. Rook also has a new experimental feature that supports bucket notifications. Finally, Snyk is going to be powering security scans to reduce the attack surface. That’s a great addition to make data storage with Rook more secure.
It’s a scale-out, software-defined distributed storage system. GlusterFS can build a versatile framework with access to the file transfer protocols (FTP) and available storage to scale rapidly without failure points. That allows you to store tons of data without worrying about security and accessibility for your Kubernetes clusters. GlusterFS also divides users and groups into logical volumes on shared storage. That allows it to handle a great number of users. It also eliminates user dependency on traditional storage arrays.
GlusterFS provides a RESTful volume management interface, Hekiti, to help automate volume provisioning from Kubernetes. This saves you the costs of manually setting up Gluster volumes and mapping them to your Kubernetes. Hekiti can support any number of GlusterFS clusters. It also permits K8 administrators to implement network storage without being stuck to a single GlusterFS cluster. GlusterFS uses block storage to store a lot of information in bits on open space in storage servers.
The latest version release had many new features, stability fixes, and code improvements. The release carried improvement in startup time with randomized port selection for bricks, heal time improvement with bigger window size, and performance improvement using readdir in fix-layout.
Ceph is an open-source, software-defined storage solution that offers pile, block, and object storage. It provides interfaces for multiple storage types within a single cluster. It has a highly scalable infrastructure. That makes it completely distributed without any point of failure. This solution also offers disaster recovery and data redundancy through erasure coding, snapshots, storage cloning, etc. The Reliable Automatic Distributed Object Stores (RADOS) layer that sits at the core of Ceph storage clusters ensures that stored data is always consistent. It performs data replication, recovery, and failure detection. Ceph can also run anywhere without any vendor lock-in and is completely self-healing and self-managing. It’s also fault-tolerant and stores data as objects within logical storage pools.
The latest Pacific version release fixed a critical bug in the OMAP format upgrade. The update also reworked NFS management to ensure NFS exports are consistently managed across different Ceph components.
LongHorn is an open-source, lightweight distributed block storage framework for Kubernetes. It separates your block storage into LongHorn volumes. That way, you can use Kubernetes volumes with or without a cloud provider. It implements distributed block storage using microservices and containers.
LongHorn can also replicate block storage across multiple nodes and data centers to improve availability. It supports automated non-disruptive upgrades. That means you can upgrade the complete LongHorn software stack without disturbing running volumes. LongHorn allows you to schedule recurring backups to external/secondary like NFS or AWS S3. You can also recover any data from a primary Kubernetes cluster from cross-cluster disaster recovery volumes in a second Kubernetes cluster.
In the latest version release, LongHorn added support for backup encryption and volume, volume clone support, policy-based backup rules, and automatic replica rebalancing. That’s preceded by a highly available RWX storage, an enhanced API, and additional storage networking support.
If you’re using Kubernetes to manage infrastructure and applications the cloud-native way, you need a cloud-native approach to storage as well. Each of these tools has its own take on how Kubernetes storage should be handled. Adopting them will make your Kubernetes systems more portable and reliable. It’ll also give you more control over how your data is used.
As with any selection process, you need to consider a thousand different factors before deciding which storage tool to pick. You need to determine your requirements and pick a tool that meets most of them. It’s also important to note which tool integrates best with your application.
You may have to practically test each solutions’ read-write speed on a test system. After that, you could roll out a winner. That’ll depend on hardware configurations and the software developers’ ingenuity. In the beginning, we mentioned that the ability to scale quickly is a key requirement in a Kubernetes storage solution. Your long-term success depends on this groundwork you’re doing here: try out the different open-source solutions!
All the solutions above can easily provide definitive storage for your data. The only difference is how they handle your data, so you should choose accordingly. This can be highly personal and specific to the use-case. When thinking about the solution, make sure you select the storage system that fits your requirements and integrates with your stack. That said, it’s also important to pick the option that has an active and responsive support system.
What are the top storage projects for Kubernetes?
The top Kubernetes open source projects are OpenEBS, Rook, GlusterFS, Ceph, and Longhorn. In this article, we defined what they are and how they work. Take a look at each one to see which one suits your system the best.
What are the key terms related to Kubernetes data storage?
The key terms are related if data exists when you delete a pod or container. Data persistence, persistent volumes (PVs), and persistent volume claims (PVCs) are of critical interest for solution implementers and developers. PVs allow data to be reused, while PVCs retain data references.
What is data persistence?
Containers and pods in Kubernetes have a short lifespan: they’re project orientated. When they’re deleted or retired, the data associated with them also gets deleted. To use the data beyond the lifecycle of a container or pod, you need to store the data somewhere to make it persistent. Data persistence means that you retain data after deletion of its container or pod. That’s useful for project recycling and creating project-based templates.
What should I look for when choosing a Kubernetes storage solution?
It needs to handle data persistence with ease, and it should enable data portability within a single cloud platform or across different cloud platforms. Most importantly, it should suit your Kubernetes needs and requirements.
What are features of a great Kubernetes storage solution?
Scaling data storage to large volumes quickly is a key requirement. The Kubernetes storage solution should also handle storage volume replication. It also needs to be able to backup and restore those volumes during failures. Lastly, it should appropriately secure data.
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