Kubernetes is revolutionizing how applications are being developed, deployed, and scaled. While Kubernetes is beneficial in container management, it lacks support for storing container data. That means Storage mechanisms need to be deployed externally on various hosts based on the needs, and these volumes may need to be scaled on the fly as the usage goes up.

In simple words, To make the data available when cluster restarts, there is a need for storage solution or mechanism which manages data operation for the cluster.

Cloud storage solutions allow this comprehensive storage mechanism for container-based applications and provide data storage solutions in cloud-based container environments.

These cloud-native storage solutions imitate the characteristics of cloud environments. These include scalability, container architecture, and high availability to easily integrate with the container management platform and provide persistent storage for container applications.

In this article, we will outline and evaluate popular cloud-native storage solutions. We will start with a quick look at the cloud-native storage tool and why are they needed for Kubernetes.

OpenEBS

OpenEBS is the leading open-source project which offers cloud-native storage solutions for Kubernetes deployments. Unlike any other storage options. OpenEBS can be integrated easily with Kubernetes, which makes it a highly rated cloud-native storage on the CNCF landscape.

OpenEBS delivers container-native storage using Kubernetes (as opposed to running on Kubernetes) to manage and store data. It follows a Container Attached Storage (CAS) architecture. That means each storage volume has a dedicated pod and a set of replica pods that are managed and deployed like any other container or microservice in Kubernetes. OpenEBS as well is deployed as a container that enables easy assigning of storage services on a per-application, cluster, or container level.

OpenEBS supports the Synchronous Replication feature, which replicates data volumes across availability zones for high availability. This feature helps build highly available stateful applications that make use of local disks on cloud providers services such as Google Kubernetes Engine and others.

OpenEBS eliminates vendor lock-in issues, which happens due to different implementation of storage architecture by various cloud storage providers. OpenEBS defines an abstraction layer between the applications and the underlying cloud service provider, making migration of data easier across different vendors without worrying about the underlying cloud storage architecture.

Unlike other storage solutions, data in OpenEBS is replicated across multiple nodes. Any node failure would affect volume replicas on that particular node only. The data on different nodes continues to be available at the same performance levels, making applications more tolerant to failures. OpenEBS CAS architecture also allows instantaneous snapshots that are created and managed using the standard kubectl command. This deep integration with Kubernetes enables work portability and makes backup and migration of data more accessible.

Every storage volume deployed in EBS is assigned a control plane, disk manager, and a data plane. A control plane controls handle periodic snapshots, cloning, policies, and metrics for that volume. At the same time, the Node Disk Manager(NDM) provides easy access to a list of node’s attached disks in the form of Block Device objects. These objects are loaded as custom resources in Kubernetes for easy attaching/detaching of storage volumes to pods without restarting them.

Coming to the data plane, users can pick various data planes for different application workflows depending upon their configuration. A Storage engine optimizes that given workflow either with a precise set of features or performance. OpenEBS currently offers three storage engines Jiva, cStor, and Open EBS Local PV.

Jiva provides standard storage capabilities(block storage) and is used generally for smaller-scale workloads compared to cStor, which offers enterprise-grade functionality and extensive snapshot features. LocalPV, on the other hand, provides performance for which it comprises advanced features like replication or snapshots.

Monitoring of the Metrics in OpenEBS is easy since containerized volumes are using CAS architecture. Parameters like volume throughput, latency, and data patterns are easily manageable and trackable through Kube-Dashboard and projects like Prometheus, FluentD, Grafana, etc.

Rook

Rook is another very popular open-source storage solution for Kubernetes, but it differs from others due to its storage orchestrating capacities. Released publicly in 2016, Rook has maintained the highest ranking in the CNCF scene for the cloud-native storage system by providing support for a diverse variety of storage solutions to integrate with the Kubernetes environment.

It is a production-grade Block and Object Storage which transforms storage volumes into self-scaling storage systems that can heal and manage themselves. In easy words, Rook allows putting storage solutions into containers and provides different mechanisms to run those storage containers on Kubernetes efficiently.

Rook also makes it simpler for cluster-admin to oversee storage frameworks via automating deployment, resource management, and scaling. It supports various storage providers, including Cassandra, Ceph, and EdgeFs, which guarantees users can pick storage innovations dependent on their workflows without agonizing over how well these storages integrate with Kubernetes.

Deploying these storage providers on Kubernetes is also very simple with Rook. Ceph is one incredible example. Deploying a Ceph cluster can be done from the YAML file using Rook, pretty much the same as the deployment of other containers in Kubernetes.

The YAML file declares the significant number of variables of what the administrator needs in the cluster. Rook spins up the clusters and starts checking in as an admin controller, ensuring that the defined configuration file in the YAML runs to its standards.

Storage providers can also be introduced on Kubernetes using kubectl command, just like some other containers in Kubernetes. Once deployed, teams can easily manage storage operations or shared file systems for their applications. Data stored is in the form of block objects created using a StorageClass and CephBlockPool for automatic mounting of storage units onto pods.

Also, Rook provides scaling, security, and resource management of clusters in one place. It has a dedicated dashboard for storage Clusters. So, administrators can check cluster health and the status of resources. Likewise, monitoring is also supported by third-party monitoring tools such as Prometheus and Grafana to manage advanced metrics, alerts, and graphs for storage containers.

GlusterFS

Gluster FS is a notable open-source project that provides Kubernetes administrators a mechanism to deploy native storage services onto their current Kubernetes cluster quickly. It is a precisely defined file storage framework that can scale to petabytes, handle a great number of users, and utilize any on-disk filesystem with the backing for different features.

GlusterFS also utilizes industry-standard conventions like SMB and NFS for networked file systems, supports replication, cloning, and bitrot identification for detecting data corruption.

However, like some other storage solutions, GlusterFS provides a RESTful volume management interface Hekiti to manage and deploy dynamically provisioned GlusterFS volumes.

With Heketi, users do not need to set up GlusterFS volumes and map them to k8s physically. It will automatically provision GlusterFS volumes with any of the supported authorization types. Heketi will itself decide the location for provisioning across the cluster, ensuring that the clones are deployed in various domains to overcome specific domain failure.

Heketi likewise supports any number of GlusterFS clusters, permitting Kubernetes administrators to implement network storage without being constrained to a single GlusterFS cluster.

GlusterFS utilizes block storage (128 kb to be exact), which stores a lot of information in pieces on open space in storage servers. It builds an exceptionally versatile framework with access to increasingly available storage and file transfer protocols to scale rapidly and without a single point of failure. That implies you can store enormous amounts of data without worrying about accessibility and security for your Kubernetes clusters.

GlusterFS likewise distribute data between different datacentres, yet keeping the data together by storing them as blocks. GlusterFS utilizes a consistent hashing algorithm to identify the location and region for a particular block. That approach helps significantly with scaling the cluster horizontally and reducing access times.

GlusterFS responds and scales more rapidly than its rivals, yet at the same time maintains the convenience of use. From the interface, users manage their data blocks as directories. Each block of data has a unique hash that users must duplicate before renaming, not losing access to the information.

Portworx

Portworx is another container storage solution intended for Kubernetes, with a focus on highly available clusters. It is a host attached storage, where every volume directly maps to the host to which it is attached. These volumes are accessed through I/O technology and provide auto-tuning based on the I/O protocol used.

Portworx is well known for its software-based products specializing in security, storage, and disaster recovery. They also offer an Enterprise-grade cloud-native solution known as PX-Enterprise. This offering provides cloud storage to applications running in the cloud, on-prem, and hybrid cloud infrastructures.

Performance and data protection is HAS(host-attached storage) type, yet containerized utilizing Kubernetes and other container management platforms.

Portworx allows you to run containerized applications with highly-availability (HA) across all your nodes, containers, cloud instances, and data centers. No worries about database container failure or downtimes. Database- driven replication of storage volume by PX-store in PX-Enterprise mitigate not only expensive costs of cluster rebuilding but also provides high performance of clusters during that failure. Portworx makes migrating workflows between multiple clusters running across the same or hybrid clouds easier. Thanks to PX-Migrate in PX-enterprise, which not only makes moving a stateful app like a database between servers effortless but also takes consistent snapshots based backups of stateful apps so that you can have full control over your data not worrying on which cloud it lives on.

PX-secure in PX-enterprise provides secure, manged-key encryption for container volumes that seamlessly integrates with well known key management frameworks like AWS KMS and Hashicorp Vault. Encryption can also be applied to any application regardless of the underlying cloud infrastructure.

PX-Autopilot in PX- enterprise provides storage management for your volumes in the cloud so you can cut your cloud storage bill in half. It Automatically resizes your container volumes or your storage clusters by optimizing your application performance requirements. It also integrates well with Amazon EBS, Google PD, and Azure Block Storage to focus more on the management of your essential data, not its underlying storage infrastructure.

Overall, Portworx other than it’s closed sourced nature, is as brilliant as it can. The performance is excellent! By far, the best. But the developer license(Portworx essentials), which only allows up to 5 TB of storage and five nodes), is limited for Kubernetes compared to the PX-Enterprise version.

Comparison Matrix

	OpenEBS	Rook	GlusterFS	Portworx
Automated resizing and provisioning	Yes, automated Provisioning across Pods	Management of Storage Resources	Yes, dynamic provisioning of clusters	Yes, automatically resize individual containers and storage volumes
Flexible Scaling	Yes	Yes	Yes	Yes
Supported Storage Types	Block and Object Storage	File, Block and Object Storage	Distributed File System, Object storage, Distributed block storage (QEMU) , Flexible storage (libgfapi)	Block and Object Storage
Integration with Managed Kubernetes Services.	Yes, Supports EKS, OpenShift, AKS, GKE, IKS	Supports Ceph which easily Integrate with AKS, GKE and EKS	Yes, easy integration with Kubernetes and its managed services	Yes, EKS, OpenShift, AKS, GKE
Data Protection and Replication	Synchronous replication	Data is replicated and encoded, advanced snapshotting capabilities	Journal based replication, bit rot detection	Synchronous replication
Open Source	Yes, Apache 2.0 License	Yes, Apache 2.0 License	Yes, GLU v2 License	No
24/7 Enterprise Support	No	No	No	Yes

Conclusion

Deciding whether to use Gluster or OpenEBS or PortWorx or Rook depends on various factors. Any of the above solutions can provide reliable storage for your data. But differences are based on how they handle the stored data.

Organizations looking for easily accessible storage that can quickly scale may find that Rook works well for automated scaling. Those who want to store massive amounts of data and want stability will prefer GlusterFS. Enterprises who want performance instead of features on a big scale will go for Portwrox. Lastly, who wants more customizations for their workloads will want to settle for OpenEBS.

I also want to mention that it’s essential to determine the requirements for any solution and pick the tool that checks most of your requirements. While there are various storage tools and approaches out there, but there is no one tool that will suit your business needs. It is crucial to define a starting point so you can start experimenting with your storage-based container application and find your perfect solution.