This is part five of our on-going series exploring tools and practices that make it easier to manage and operate cloud native environments. Part 1 and 2 reviewed cloud native development and CICD tools, part 3 outlined cloud native network tools and part 4 evaluated service mesh tools. We reviewed tools in each category based on the feature set they provide and their ease of deployment and continued operations in Kubernetes based cloud native environments.
In this installment we will outline and evaluate cloud native storage tools. We will start off with a quick look at cloud native storage tools and why they are needed before moving on to a comparison of cloud native storage tools from the CNCF cloud native landscape.
Cloud native storage is storage technology geared towards use in cloud native environments. Cloud native environments are dynamic by nature and represent the convergence of multiple trends in the broader IT landscape including orchestration, containerisation, microservices, service meshes, DevOps and CICD. As such storage needs to evolve too in order to keep pace with these technologies.
Cloud native storage platforms enable comprehensive data management for stateful applications and provide solutions to the problem of persistent data storage in Kubernetes based cloud native environments.
Most cloud native storage solutions emulate the characteristics of cloud native tools and environments outlined by the CNCF. Some of these characteristics include, scalability, high availability, vendor-neutrality and being natively secure, resilient, manageable, observable, declarative in nature and API driven.
Let's now move on to a comparison of the top most rated cloud native storage solutions on the CNCF cloud native landscape.
OpenEbs is an opensource cloud native storage solution with the fourth highest rating on the CNCF landscape. It has a broad integration footprint with Kubernetes and can be easily installed and configured using Helm or Kubectl.
OpenEbs creates a software-defined storage infrastructure for Kubernetes applications and acts as an abstraction layer between those applications and the disparate underlying storage providers. In the process it reduces maintenance overhead, cuts costs and makes it easier to manage storage for stateful applications.
OpenEbs uses the container attached storage (CAS) model to abstract storage controllers as Kubernetes pods. Each storage volume has a dedicated pod as well as a set of replica pods. This allows storage volumes to be orchestrated and deployed similar to any other container or microservice.
Since CAS containerises storage and abstracts storage disks and pools as Kubernetes CRDs, it can be easily integrated with other cloud native solutions for management, provisioning and monitoring. This also allows for ease of orchestration and deployment using Kubernetes across cloud, bare metal and on-premises.
Once deployed, the OpenEbs architecture comprises a control plane, a data plane and a node disk manager (NDM). The control plane handles volume provisioning, snapshots, replication, cloning, storage policies and metric export. The data plane implements the IO path using multiple pluggable storage engines including Jiva and cStor.
The NDM component makes it easier to manage node-attached disks by detecting and loading them as Kubernetes custom resources called BlockDevice objects. It then provides an easy to access inventory of block devices, predicts block device failures, and allows for attaching/detaching block devices to pods without the need for restarts.
OpenEbs supports synchronous replication of data volumes across availability zones for high availability. This feature is especially useful when building highly available stateful applications that use public cloud provider local disks.
It also allows DevOps to create instantaneous snapshots and manage them using native Kubectl commands in the process enabling workload portability and data migration. OpenEbs also integrates with Velero using a native velero plugin to enable volume backup and restore.
Another useful feature is the support for creating, updating and managing granular storage policies. DevOps can create and manage policies for each individual volume including e.g. controlling the amount of volume replicas (ReplicaCount), and automatically launching a side-car to export Prometheus metrics (VolumeMonitor).
Rook is another open source cloud native storage solution with the third highest rating on the CNCF landscape. Rook is a storage orchestrator, allowing DevOps to offload the management of multiple storage backends to it. It can be easily installed in Kubernetes environments using the dedicated Kubernetes operator for each supported storage provider.
Rook makes it easier to manage distributed storage systems by automating deployment, bootstrapping, configuration, provisioning, scaling, upgrading, migration, disaster recovery, monitoring, and resource management. Out of the box support for multiple storage backends including Ceph, EdgeFs and Cassondra ensures DevOps can pick and choose storage technologies based on their specific use case without having to worry about how well they integrate and run on Kubernetes.
Installing and operating these storage backends on Kubernetes is also simpler with Rook. Ceph, a distributed storage solution for block and object storage, and shared file systems is one good example.
Ceph can be installed on Kubernetes using kubectl or a dedicated operator. Once deployed DevOps can mount block and object storage or shared file systems for their applications using native Kubernetes primitives. For example block storage can be provisioned using a StorageClass and CephBlockPool (K8s CRD) definitions and consumed using the Ceph-CSI driver that automatically mounts storage to pods.
In addition the Rook operator manages CRDs for storage pools, object storage and filesystems. It also spins up and monitors Ceph monitor pods, responsible for maintaining a copy of the cluster map. Since Rook spins up monitor pods as part of ReplicaSets, they are always restarted by Kubernetes in case of failure. Rook can also terminate a monitor pod that fails to restart and replace it with a new one.
Rook also provides a dedicated dashboard for Ceph clusters where DevOps can monitor cluster health and status of cluster resources. Ceph clusters provisioned using Rook also support monitoring via Prometheus and Grafana. Once installed DevOps can monitor ceph cluster metrics, create alerts and graph them using Grafana or use one of the prebuilt Grafana dashboards.
Want to dig deeper into Kubernetes based cloud native environments? Download the Complete CIOs Guide to Kubernetes:
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