What is Persistent Storage?

Last Updated : 18 Oct, 2023

Any data storage system that keeps data after its power is turned off is said to be using persistent storage. It's also known as nonvolatile storage at times. Persistent storage in the context of containerization refers to storage volumes that are accessible after a container has stopped running. These volumes are typically connected to stateful applications like databases. Ephemeral storage volumes, which are linked to stateless apps that live and die with containers, can be contrasted with persistent storage volumes.

What is Persistent Storage?

Persistent Storage is defined as a device that is used for storing the data. Persistent storage saves the data even if the power is turned off therefore they are also known as non-volatile material. Persistent storage systems are in the form of files, blocks and the object storage. Some typical type of persistent storage consists of optical media such as DVDs, and magnetic media such as hard disk drives and tapes. Persistent storage systems are used because it increases the performance of the system and enables a fundamental change in the overall computing architectures, therefore persistent storage is used in various applications such as database, storage, Big Data, cloud computing, IOT applications, virtualization and Artificial Intelligence applications.

Types of Persistent Storage

1. Kubernetes

Kubernetes is used by OpenShift which is a platform as a service offering used for logistic containerized application deployments across a cluster. Earlier the storage volumes needed to be registered manually and had to be pre-provisioned as PersistentVolume (PV). The objects of the storage class provide a feature that creates a storage volume for on-demand applications by enabling the specification of a provisioner.

2. Containers

OpenStack Swift is used for storing the data that is in the form of static data or binary objects such as massive data sets this images media files etc. OpenStack Swift is a distributed storage solution that makes use of bins for organizing this objects. Only the volumes contents can be accessed by the instances where as objects within a container can be accessed by the rest API of the object storage. Therefore any service can use object storage as a repository in public cloud or a private cloud.

Persistent Solid-State Storage

Solid state drives are the examples of permanent storage. Solid state drives differ from other types of Persistent media. The chips that are used for cache devices and RAM are types of solid state storage, these means that the information is deleted once the power is off. Some type of storage such as flashed based RAM and non volatile RAM are persistent in nature because once the primary source of energy is cut of they makes use of the battery power. The disadvantage of non persistent storage resources is loss of data and even offers less security as compared to persistent storage.

Persistent Storage and Containerization

In the past few years, containerization is being considered as a most common way for packaging of software, and converting operating systems into a transportable and isolated modules that can be generated as well as destroyed as much as they are possible. But permanent storage is not allowed by containerization. The data that is being generated by the containerized app disappears once the app completes its function. For retaining the data generated by container container applications new software and storage is being recently developed by some vendors. These advances in the storage containers solves the problems of retaining of more ephemeral storage volumes.

How Does Persistent Storage Work With Containers?

PVs are defined as the resources that have a independent lifecycle that makes use of PV. These are known as physical volume present on host machines that are used to store persistent data. The storage resources are provided in clusters by the PersistentVolumes. These volumes can be provisioned statistically or dynamically and can even be customized for use by defining their properties such as size, performance and the access modes.

PersistentVolumeClaim (PVC) are defined as the requests for resources that acts like a claim checks to the resources. It is a request platform used for creating the PersistentVolume and for attaching the PVs to pods through PVC.

Persistent Storage Architecture

Persistent storage architecture consists of three approaches. Each approach has a unique use cases as well as the imitations. Below are the three storage approaches of Persistent storage architecture:

1. Object Persistent Architecture

The object persistent architecture stores the data as object or a key value database. This approach makes use of object relational mapping (ORM). Object persistent architecture approach is used when data does not have any defined schema for it the object. Object relational mapping (ORM) then handles its overall storage and the retrieval of data.

2. Block Persistent Architecture

Block persistent architecture is used for storing large files blocks. Persistent architecture makes use of block level storage devices. Using block persistent architecture is beneficial when we need to store large amount of data. These approach makes use of multiple blocks that helps to increase the overall storage capacity

3. File store Persistent Architecture

File store persistent architecture makes use of a file system for storing the data. File store persistent architecture approach is mostly useful for the applications that requires frequent retrieval of files and when the user needs an interface for managing them.