This blog serves as an introduction to Kubernetes storage, as well as key concepts and how to choose the best Kubernetes data storage solution for your organization.
What is Kubernetes Storage?
Kubernetes storage can refer to any long- or short-term storage solution for Kubernetes applications and their underlying data. However, in most contexts, Kubernetes storage refers to longer term storage solutions whose lifecycle is decoupled from that of individual Kubernetes pods or nodes, and enables data to persist outside of those pods – or Kubernetes persistent storage.
What is Persistent Storage for Kubernetes?
While Kubernetes excels at managing containerized application logic, the containers and pods managed by Kubernetes itself are short-lived by design; though containers and pods can store data, once they are deleted, the data they store is deleted as well.
Persistent storage for Kubernetes allows data to persist beyond the lifetime of an individual container or pod. Purpose-built Kubernetes storage solutions are designed to leverage Kubernetes primitives, concepts, and management efficiencies while addressing traditional storage needs like backup, disaster recovery, and security.
Why does Kubernetes need Persistent Storage?
Most modern enterprise applications require persistent storage, making the ephemeral storage within containers or pods unsuitable for many enterprise use cases. In short, Kubernetes storage is a critical need for any platform or storage team supporting stateful, containerized applications at scale.
Common Storage Challenges with Containers and Kubernetes
Deploying, scaling, and managing storage for Kubernetes applications involve more than just ensuring data persistence outside of the container lifecycle. As Kubernetes applications scale quickly and dynamically, they introduce additional challenges:.
Kubernetes storage and data management challenges
- Data persistence: While Kubernetes provides a straightforward way to manage containers themselves, managing the underlying Kubernetes persistent storage can be more challenging, especially across container restarts or pod migrations.
- Resource management: Kubernetes does not have a native way to manage storage across nodes, which can lead to an uneven distribution of resources, and poorer overall performance.
- Data protection: Protecting data against loss or damage is critical to any deployment, but Kubernetes offers only limited data protection mechanisms, such as snapshots and replication controllers.
- Performance monitoring: Monitoring performance is crucial for detecting issues and optimizing resources in distributed systems. Kubernetes does not provide native tools for performance monitoring.
- Scalability: Kubernetes scales horizontally by adding more nodes to a cluster, but this increased load can cause supporting storage nodes to become oversubscribed or to fail; Kubernetes persistent storage solutions must scale along with compute clusters.
- Security: To ensure proper security, infrastructure and platform teams must select a storage solution with robust authentication, authorization, and encryption to protect confidential data.
- Cost: The cost of storage management, replication, and backup must be factored into the overall cost. The ideal Kubernetes storage solution is automated and cloud-native to optimize resources and performance, while reducing time spent on manual, ticketed deployment routines.
What are the Benefits of Specialized Kubernetes Storage?
The right storage solution can help simplify and streamline Kubernetes deployments, while providing a range of benefits such as scalability, resiliency, flexibility, automation, and performance.
Greater Scalability
Dedicated Kubernetes storage solutions should offer a way to automatically and dynamically increase or decrease capacity to accommodate changing workloads, without manual intervention.
Data Resiliency
Persistent storage for Kubernetes must be highly resilient to ensure that critical data is always available and protected in case of failures or disaster. A strong Kubernetes storage solution enables efficient data replication across nodes and clusters, reducing data transfer times, and improving overall application performance.
Reduced Complexity
For organizations working in a hybrid- or multi-cloud environment, a dedicated Kubernetes storage solution can streamline storage management by abstracting specialized characteristics of your infrastructure, and standardizing to your selected data storage platform.
Agility and Portability
Just as containerized applications can be moved from one cluster to another, Kubernetes storage can be moved along with applications due to the standardization Kubernetes offers across environments. Kubernetes storage makes data more easily portable across different clusters, through promotion through dev / test / production environments, or across hybrid- and multi-cloud environments.
What are Common Use Cases for Kubernetes Storage?
Today, Kubernetes and containers have evolved from its early days to support more complex, stateful applications. Some of the most commonly used container images are for databases such as PostgreSQL, Kafka, and MongoDB, indicating the growing importance of running data on Kubernetes.
Data Protection
Kubernetes applications require additional capabilities that traditional storage solutions don’t provide. For example, Kubernetes applications are based on containers, not machines; traditional storage solutions do not offer granular controls based on individual containers. Traditional storage solutions are also not aware of specific Kubernetes object and namespace configurations. The right Kubernetes storage solution closes these gaps, while implementing greater automation for best practices for backup and disaster recovery
Unified storage for containers and virtual machines
With the general availability of KubeVirt, the world is no longer split into containers and Kubernetes vs virtual machines. Today, many organizations seek to operate VMs alongside containers, using Kubernetes. This is an emerging use case for organizations, but one that requires a consistent Kubernetes storage operating model across VMs, containers, and cloud environments.
Database Provisioning
Application development teams are under pressure to innovate quickly, and have become accustomed to using containers to deploy business logic. But to do so, they require fast, self-service to databases and other services, deployed on their infrastructure of choice, often with CI/CD, or other automated workflows. A specialized Kubernetes storage and data management solution can fulfill the organization’s requirements for deployment and management, ensuring adequate provisioning of storage, backup, and data recovery to meet business needs.
What are different Kubernetes (K8s) Storage Concepts?
Since most enterprise Kubernetes applications need persistent data and storage, Kubernetes has several ways to attach storage to Kubernetes applications.
Container Storage Interface (CSI)
What is Container Storage Interface (CSI) in Kubernetes?
The Container Storage Interface (CSI) is an open standard to connect storage devices to Kubernetes. Third-party storage solutions can connect to Kubernetes through a plugin based on the open CSI specification.
What are the pros and cons of using CSI Drivers?
Traditional storage systems using the CSI connector bind to a specific hardware device, making portability and scalability of containers and storage difficult in a hybrid cloud environment. Today, both cloud-native and traditional storage vendors provide CSI drivers for their solutions, opening many options for users. However, organizations using multiple third-party storage solutions to support Kubernetes applications must also manage many CSI drivers, providing a major operational challenge.
Kubernetes PersistentVolume (PV) and Persistent Volume Claims (PVC)
What are PersistentVolume (PV) and Persistent Volume Claims (PVC)?
Persistent volumes are a layer of abstraction between the storage used by a container and its underlying infrastructure, ultimately allowing for greater flexibility and portability in containerized environments. A PersistentVolumeClaim is the process that automatically assigns or creates a storage resource to a Kubernetes pod.
Persistent volumes can be backed up and restored, providing an additional layer of protection. They also help decouple the storage configuration from application deployment, so developers can focus on their applications rather than worry about storage infrastructure. It also allows for greater flexibility when it comes to deploying applications across different cloud environments. For a deeper understanding of persistent volumes, visit our Kubernetes Persistent Volume tutorial.
Static vs dynamic provisioning
With static provisioning, the cluster storage administrator allocates persistent Kubernetes storage with a specific configuration and fixed attributes, such as volume size. This is helpful for use cases in which storage is well-defined with predictable consumption.
Dynamic provisioning enables the automatic creation of persistent volumes, as soon as the application requests them and need arises. With dynamic provisioning, storage can be automatically provisioned, with persistent volumes based on pre-defined storage classes and policies. This is helpful in use cases where workloads are more dynamic, require greater scaling, and are less predictable.
Kubernetes Storage Classes
What are Storage Classes?
A StorageClass offers a simplified approach to defining the range of storage options available for Kubernetes applications. Each StorageClass can be customized to provide specific levels of performance and reliability for different types of applications, allowing developers to specify the required level of quality of service (QoS) for their applications, ensuring applications have access to storage the appropriate levels of performance and reliability.
For example, a storage class might be optimized for high-performance workloads that require low latency and high I/O throughput, while another storage class might be designed for less critical applications that can tolerate lower levels of performance.
Default vs Custom StorageClass
A default StorageClass is just that: it’s the default configuration applied to any PersistentVolumeClaim (PVC) that does not specify a StorageClass. A custom StorageClass can be defined and applied to new applications and workloads as needed in place of a default StorageClass.
What are Best Practices for Kubernetes Storage?
Choosing the right storage Kubernetes Storage Solution
While every organization must consider the different application types, performance needs, and costs that are best for them. Most organizations establishing a Kubernetes platform will need automated operations, container-granular and application aware data protection, and security :
Streamlined, Automated Performance Optimization
Cloud-native applications and environments are highly dynamic. A powerful Kubernetes storage solution can streamline and automate critical operations, such as provisioning, capacity management, volume placement, and I/O tuning.
Application-aware Backup and Data Protection
In a traditional storage and application environment, data backup and protection are often purchased separately from different vendors, or managed as separate solutions. However, Kubernetes applications, their data, and the environments which they are run and stored change frequently; a solution purpose-built for Kubernetes can ensure that backup and recovery processes are tightly integrated with storage itself, and restore apps and data to the correct configuration and location if needed (read more about essential capabilities of data protection for Kubernetes)
Security Considerations
While persistent storage for Kubernetes must be highly dynamic, it is still subject to the traditional security and compliance requirements as traditional storage. A strong Kubernetes storage solution not only meets traditional needs such as encryption and RBAC, but adjusts to meet the needs of a fast-changing, dynami, cloud-native environment.
Kubernetes Storage Solutions with Portworx
Portworx by Pure Storage is the industry-leading solution for Kubernetes storage and data services, helping platform engineering and DevOps leaders manage complexity across any cloud environment. Portworx accelerates time to revenue, delivers data resiliency, and agility at enterprise scale without compromise. This comprehensive solution that includes:
- Automatic Kubernetes storage provisioning and resizing
- Disaster recovery
- Data encryption
- Snapshots and backups with immutability
- Data Availability across hosts
- Database Platform-as-a-service
To get started and learn more about Portworx, contact us and request a demo or check out one of our upcoming, guided hands-on labs.