Raghvendra Tripathi

SunilKumar HS

The Container Storage Interface (CSI) is a standard for exposing file and block storage to containerized workloads on Kubernetes, OpenShift and so on. CSI helps third-party storage providers (for example PowerFlex) to write plugins for OpenShift to consume storage from backends as persistent storage.

CSI architecture

CSI driver for Dell EMC VxFlex OS can be installed using Dell EMC Storage CSI Operator. It is a community operator and can be deployed using OperatorHub.io.

Master nodes components do not communicate directly with CSI driver. It interacts only with API server on Master nodes. It MUST watch the Kubernetes API and trigger the appropriate CSI operations against it. Kubelet discovers CSI drivers using kubelet plug-in registration mechanism. It directly issues calls to CSI driver.

CSI components

External Provisioner –The CSI external provisioner is a sidecar container that watches the k8s API server for PersistentVolumeClaim objects. It calls CreateVolume against the specified CSI endpoint to provision a volume.

External Attacher – The CSI external attacher is a sidecar container that watches the API server for VolumeAttachment objects and triggers controller [Publish|Unpublish] volume operations against a CSI endpoint.

Driver Registrar

• Node-driver-registrar – The CSI node driver registrar is a sidecar container that fetches driver information from a CSI endpoint and registers it with the kubelet on that node.
• Cluster-driver-registrar – The CSI cluster driver registrar is a sidecar container that registers a CSI driver with a k8s cluster by creating a CSIDriver object.

CSI Controller plug-in – The controller component can be deployed as a Deployment or StatefulSet on any node in the cluster. It consists of the CSI driver that implements the CSI Controller service.

CSI Identity – It enables k8s components and CSI containers to identify the driver.

CSI Node Plugin –The node component should be deployed on every node in the cluster through a DaemonSet. It consists of the CSI driver that implements the CSI Node service and the node driver registrar sidecar container.

CSI and Persistent Storage

Storage within OpenShift Container Platform 4.x is managed from worker nodes. The CSI API uses two new resources: PersistentVolume (PV) and PersistentVolumeClaim (PVC) objects.

Persistent Volumes – Kubernetes provides physical storage devices to the cluster in the form of objects called Persistent Volumes. 

 Persistent Volume Claim – This object lets pods use storage from Persistent Volumes.

Storage Class – This object helps you create PV/PVC pair for pods. It stores information about creating a persistent volume.

CSI driver capabilities

Static Provisioning – This allows you to manually make existing PowerFlex storage available to the cluster.   

Dynamic Provisioning - Storage volumes can be created on-demand.  Storage resources are dynamically provisioned using the provisioner that is specified by the StorageClass object.

Retain Reclaiming – Once PersistentVolumeClaim is deleted, the corresponding PersistentVolume is not deleted rather moved to Released state and its data can be manually recovered.

Delete Reclaiming – It is the default reclaim policy and unlike Retain policy persistent volume is deleted.

Access Mode - ReadWriteOnce -- the volume can be mounted as read/write by a single node.

Supported FS - ext4/xfs.

Raw Block Volumes: Using Raw block option, PV can be attached to pod or app directly without formatting with ext4 or xfs file system.

Kent Stevens, Product Management, PowerFlex
Brian Dean, Senior Principal Engineer, TME, PowerFlex
Michael Richtberg, Chief Strategy Architect, PowerFlex

We observe customers repatriating key applications from the Cloud, help you think about where to run your key applications, and explain how PowerFlex’s unique architecture meets the demands of these workloads in running and transforming your business

For critical software applications you depend upon to power core business and operational processes, moving to “The Cloud” might seem the easiest way to gain the agility to transform the surrounding business processes. Yet we see many of our customers making the move back home, back “On-Prem” for these performance-sensitive critical workloads – or resisting the urge to move to The Cloud in the first place. PowerFlex is proving to deliver agility and ease of operations for the IT infrastructure for high-value, large-scale workloads and data-center consolidation, along with a predictable cost profile – as a Cloud-like environment enabling you to reach your business objectives safely within your own data center or at co-lo facilities.

IDC recently found that 80% of their customers had repatriation activities, and 50% of public-cloud based applications were targeted to move to hosted-private cloud or on-premises locations within two years⁽¹⁾.  IDC notes that the main drivers for repatriation are security, performance, cost, and control.   Findings reported by 451 Research⁽²⁾ show cost and performance as the top disadvantages when comparing on-premises storage to cloud storage services. We’ve further observed that core business-critical applications are a significant part of these migration activities.  

If you’ve heard the term “data gravity,” which relates to the difficulty in moving data to and from the cloud and that may only be part of the problem. “Application” gravity is likely a bigger problem for performance sensitive workloads that struggle to achieve the required business results because of scale and performance limitations of cloud storage services.

Transformation is the savior of your business – but a problem for your key business applications

Business transformation impacts the data-processing infrastructure in important ways:  Applications that were stable and seldom touched are now the subject of massive changes on an ongoing basis. Revamped and intelligent business processes require new pieces of data, increasing the storage requirements and those smarts (the newly automated or augmented decision-making) require constant tuning and adjustments. This is not what you want for applications that power your most important business workflows that generate your profitability.  You need maximum control and full purview over this environment to avoid unexpected disruptions.  It’s a well-known dilemma that you must change the tires while the car is driving down the road – and today’s transformation projects can take this to the extreme.  

The infrastructure used to host such high-profile applications – computing, storage and networking – must be operated at scale yet still be ready to grow and evolve. It must be resilient, remain available when hardware fails, and be able to transform without interruption to the business.  

Does the public cloud deliver the results you expected?

Do your applications require certain minimum amounts of throughput? Are there latency thresholds you consider critical? Do you require large data capacities and the ability to scale as demands grow? Do require certain levels of availability? You may assume all these requirements come with a “storage” product offered by the public cloud platforms, but most fall short of meeting these needs. Some require over-provisioning to get better performance. High availability options may be lacking. The highest performing options have capacity scale limitations and can be prohibitively expensive. If you assume what you’ve been using on-prem comes from a hyperscaler, you may be quite surprised that there are substantial gaps that require expensive application rearchitecting to be “cloud native” which may become budget busters. These public cloud attributes can lead to “application gravity” gaps.

While the agility of it is tempting, the unexpected costliness of moving everything to the public cloud has turned back more than one company.  When evaluating the economics and business justification for Cloud solutions, many costs associated with full-scale operations, spikes in demand or extended services can be hard to estimate, and can turn out to be large and unpredictable.  

The full price of cloud adoption must account for the required levels of resiliency, management infrastructure, storage and analytics for operational data, security solutions, and scaling up the resources to realistic production levels.  Recognizing all the necessary services and scale may undermine what might have initially appeared to be a solid cost justification. Once the budget is established, active effort and attention must be devoted to monitoring and oversight.   Adapting to unexpected operational events, such as bursting or autoscaling for temporary spikes in workload or traffic, can bring unforeseen leaps in the monthly bill.  Such situations can be especially hard to predict and plan for – and very difficult to control.

You want the speed, convenience and elasticity of running in the cloud - but how do you ensure that agility while staying within the necessary bounds of cost and oversight?  Truly transformative infrastructure allows businesses to consolidate compute and storage for disparate workloads onto a single unified infrastructure to simplify their environment, increase agility, improve resiliency and lower operational costs.  And your potential payoff is big with far easier scaling, more efficient hardware utilization, and less time spent figuring out how to get things right or tracking down issues that complicate disparate system architectures.  

Software-Defined is the Future

IDC Predicts that by 2024, software-defined infrastructure solutions will account for 30% of storage solutions⁽³⁾.  At the heart of the PowerFlex family, and the enabler of its flexibility, scale and performance is PowerFlex software-defined storage.  The ease and reliability of deployment and operation is provided by PowerFlex Manager, an IT operations and lifecycle management tool for full visibility and control over the PowerFlex infrastructure solutions. 

PowerFlex’s unmatched combination of flexibility, elasticity, and simplicity with predictable high performance - at any scale - makes it ideally suited to be the common infrastructure for any company.  Utilizing software defined storage (SDS) and hosting multiple heterogeneous computing environments, PowerFlex enables growth, consolidation, and change with cloud-like elasticity – without barriers that could impede your business.

The resulting unique architecture of the PowerFlex family easily meets the large-scale, always-on requirements of our customers’ core enterprise applications.  The power and resiliency of the PowerFlex infrastructure platforms handle everything from high-performance enterprise databases, to web-scale transaction processing, to demanding business solutions in various industries including healthcare, utilities and energy.  And this includes the new big-data and analytical workloads that are quickly augmenting the core applications as the business processes are being transformed.

PowerFlex: A Unique Platform for Operating and Transforming Critical Applications

PowerFlex provides the flexibility to utilize your choice of tools and solutions to drive your transformation and consolidation, while controlling the costs of the relentless expansion in data processing.  PowerFlex provides the modularity to adapt and grow efficiently while providing the manageability to simplify your operations and reduce costs.  It provides the scalable infrastructure on-premises to allow you focus on your business operations. PowerFlex on-demand options by the end of 2020 enable an elastic OPEX consumption model as well.

As your business needs change, PowerFlex provides a non-disruptive path of adaptability. As you need more compute, storage or application workloads, PowerFlex modularly expands without complex data migration services. As your application infrastructure needs change from virtualization to containers and bare metal, PowerFlex can mix and match these in any combination necessary without needing physical changes or cluster segmentation. PowerFlex provides future-proof capabilities that keep up with your demands with six nines of availability and linear scalability.

With the dynamic new pace of growth and change, PowerFlex can ensure you stay in charge while enabling the agility to adapt efficiently.   PowerFlex enables you to leverage the advantages of oversight and cost-effectiveness of the on-premises environment with the ability to meet transformation head-on.

For more information, see PowerFlex on Dell EMC.com, or reach out to Contact Us.

footnotes: 

^{1 IDC Cloud Repatriation Accelerates in a Multi-Cloud World, July 2018}

² 451 Research, 2020 Voice of the Enterprise

3 IDC FutureScape: Worldwide Enterprise Infrastructure 2020 Predictions, October 2019