Introducing the PowerFlex Solution

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Introducing the PowerFlex Solution is an article that introduces the Dell PowerFlex solution.

First and foremost, what is Dell PowerFlex?

Dell PowerFlex is a software-defined storage platform that combines storage and compute resources into a single system. It offers high performance, scalability, and flexibility for modern data center needs. PowerFlex supports block storage in two-layer (compute and storage separate) or single-layer (hyper-converged) deployments. It is ideal for applications like databases, virtualized environments, and containers. In addition to providing block storage, PowerFlex can also provide file services such as SMB and NFS shares.

PowerFlex Software Architecture

PowerFlex is a software layer that runs on Dell-validated servers. All PowerFlex nodes work in a cluster. The cluster combines components that enable local storage devices’ consumption, virtualization, and presentation as a shared, software-defined storage (SDS) solution.

At this point, we can highlight the following components that form the PowerFlex architecture:

Meta Data Manager (MDM)
Storage Data Server (SDS)
Storage Dala Client (SDC)
File Services Node (FSN)
Storage Data Target (SDT)
Storage Data Replication (SDR)
Lightweight Installer Agent (LIA)

Each component can be understood (simply) as a piece of installable and configurable software. We will explore each one in the following sections of this article.

Meta Data Manager (MDM)

The MDM is the authority that controls and tracks data storage ownership, mapping, and protection. As volumes are created, the MDM provides the information to application servers needed to connect to the cluster’s virtualized storage.

To be clear here, we create Volumes under the Block Storage provided by the PowerFlex. Volumes works like LUNs and can be mapped by clients over the network!

The MDM also ensures the distribution of writes to ensure balanced resource utilization. The MDM also handles data integrity. It runs periodic background processes to validate and guarantee data integrity.

MDM nodes are deployed in a clustered configuration to ensure availability. Despite all of the MDM’s responsibilities, user data never passes through the MDM. In the following picture, we can see a PowerFlex architecture and when the MDM works:

The Meta Data Manager (MDM) can be considered part of the control-plane layer. It is responsible for managing and orchestrating the overall system, including metadata, cluster configuration, and system operations. The MDM does not handle actual data I/O (which is the responsibility of the data plane) but instead oversees the coordination and management tasks, making it analogous to a control plane in traditional architectures.

Storage Data Server (SDS)

The SDS is a software daemon that enables a cluster server to contribute local storage devices to an aggregate storage pool. It owns the contributing devices and, together with the other SDSs, forms a protected mesh from which storage pools are created.

In other words, each physical server can contributes with their local disks and, together, storage pools can be created under these local disks. Each physical server needs to have the SDS software installed and configured. As we leanerd, the MDM cluster is responsible to manage and orchestrate the overall system, and it includes the management of SDS devices.

The SDS is also responsible for performing requested Software Data Client (SDC) back-end I/O operations and MDM rebuilds and rebalance operations.

As we could see, when is necessary to execute a rebuild or rebalance operation, the MDM cluster is reponsible for managing this operation. The MDM cluster creates a task and sends it to each SDS device.

In the following picture, we can see SDS devices working together to create the Logical Volumes; the result of this meshed grouping of local disk devices:

Storage Data Client (SDC)

The Storage Data Client (SDC) is a block device driver that exposes shared block volumes from the SDS to the operating system (to the client OS). The SDC software runs on the same server as the application.

Practically, an application issues an I/O request, and the SDC fulfills the request regardless of the SDS on which the requested blocks physically reside.

The SDC communicates with other nodes in the PowerFlex architecture over TCP/IP-based protocol!

The only I/O in the stack that the SDC intercepts are the I/O that are directed at the volumes that belong to PowerFlex. In the following picture, we can have an idea about it:

File Services Node (FSN)

The FSN software component allows the PowerFlex cluster to make data available over file-based protocols:

Server Message Block (SMB): A shared resource on an SMB server, typically used by Windows clients.
Network File System (NFS): NFS is the most common protocol for sharing files between UNIX systems over a network. NFS versions v3 and v4 are supported.
File Transfer Protocol (FTP): A standard protocol to transfer files over a TCP-based network. Both secure and non-secure FTP are supported.

In the following picture, we can see how FSN devices work to create the shares for NAS clients:

Storage Data Target (SDT)

The SDT (also known as the NVMe Target) manages host connections and controllers connected over NVMe/TCP.

Since SDT works as a Logical Storage Endpoint, it programmatically forwards administrative and I/O commands to the SDS. This makes traffic from an SDT look like it came from an SDC, as we can see in the following picture:

Storage Data Replication (SDR)

The SDR component extends the PowerFlex cluster beyond a single site. It is an optional component that manages all aspects of PowerFlex replication.

The Storage Data Replication (SDR) needs to be installed on each SDS device!

It intercepts write I/Os from the SDC for replication and passes it to the SDS for storage. If the data written is being replicated, the I/O is redirected to the SDR instead of the SDS.

In simple terms:
-- to the SDC, SDR appears as an SDS;
-- to the SDS, SDR appears to be an SDC.

As we can see in the following picture, two PowerFlex systems are placed in different physical locations. The desired data is replication between them to guarantee the data availability for disaster recovery purposes, for example:

Lightweight Installer Agent (LIA)

Each node has a Lightweight Agent. It is used to upgrade the component on which it is installed and is required for many maintenance operations and system monitoring for health and connectivity checks.

Meta Data Manager (MDM) Cluster

As we learned, the MDM is a software part of the PowerFlex software architecture/stack.
Simply put, MDM is a metadata database that is vital for the cluster to work fine!

A multi-MDM environment (MDM cluster) consists of one primary MDM, while others are secondary or tiebreakers.

Three or five instances of MDM run on different servers to support high availability.
We have the primary, secondary, and tiebreaker roles in three MDM clusters.
The following picture shows all node roles in a five-MDM cluster:

In summary:

Cluster Mode	Member	Description
Three-node	– Primary MDM – Secondary MDM – Tiebreaker	Two copies of the MDM repository – *can withstand one MDM failure.*
Five-node	– Primary MDM – Two Secondary MDM – Two Tiebreaker	Three copies of the MDM repository – *can withstand two MDM failures.*

Primary MDM: The MDM in the cluster controls the SDSs and SDCs. It contains and updates the MDM repository, which is the database that stores the SDS configuration. The repository also specifies how data is distributed between the SDSs in the system. This repository is constantly replicated to the Secondary MDM so they can take over during a system component failure, such as a network link. Every MDM cluster has one Primary MDM.

Secondary MDM: An MDM in the cluster that is ready to assume the role of the Primary MDM if necessary. In a three-node cluster, there is one Secondary MDM, thus enabling a single point of failure. In a five-node cluster, there are two Secondary MDMs, allowing two points of failure. This increased resiliency is a significant benefit of using the five-node cluster.

Tiebreaker: An MDM whose only role is to help determine the primary MDM. In a five-node cluster, an additional standby tiebreaker is configured, which increases the system’s resiliency if there is a failure.

Virtual IP addresses can be defined for the MDM cluster.

All Software Data Clients (SDCs) needs to be configured to access the PowerFlex resources through MDM IP addresses.
In a normal three MDM cluster without using Virtual IPs, each SDC device needs to be configured to reach the MDM primary node IP. In case of MDM primary node failure, no automatic failover happens.
Using Virtual IPs, we can define at least one Virtual IP and this IP will be used to configure each SDC device. It works like a proxy, intercepting all SDC's requests and directing it to the primary MDM.

A maximum of four virtual IPs are supported (but, in my opinion, configuring at least one virtual IP will satisfy the majority of environments).

PowerFlex Offerings

PowerFlex offerings include a PowerFlex rack, appliance, custom node, and software-only option.

Each offering comes with PowerFlex software-defined storage designed to meet differing customer requirements and expectations.

PowerFlex Deployment Options Overview

Deployment Type	Description
Hyperconverged	Metadata Manager, compute, and storage reside within the same server. SDR is supported on PowerFlex hyperconverged nodes.
Two-layer	Separates compute resources from storage resources, allowing the independent expansion of compute or storage resources. It consists of PowerFlex compute-only nodes (supporting the SDC) and PowerFlex storage-only nodes (connected to and managed by the SDS). PowerFlex compute-only nodes host end-user applications. PowerFlex storage-only nodes contribute storage to the system pool. PowerFlex Metadata Manager (MDM) runs on PowerFlex storage-only nodes.
Hybrid hyperconverged	It separates compute resources from storage resources, allowing the independent expansion of compute or storage resources. It consists of PowerFlex compute-only nodes (supporting the SDC) and PowerFlex storage-only nodes (connected to and managed by the SDS). PowerFlex compute-only nodes host end-user applications, while PowerFlex storage-only nodes contribute storage to the system pool. PowerFlex Metadata Manager (MDM) runs on PowerFlex storage-only nodes.

About compute-only and storage-only nodes:

PowerFlex compute-only nodes	It consists of PowerFlex compute-only nodes (supporting the SDC) on Microsoft Windows, VMware ESXi, CentOS, and Red Hat Enterprise Linux. These nodes host end-user applications. NOTE: Windows compute-only nodes must be deployed manually instead of PowerFlex Manager.
PowerFlex storage-only nodes	It consists of embedded operating system nodes contributing storage resources to the virtual environment. The back-end traffic shares the same PowerFlex data networks. No SDC components are installed on this node. PowerFlex Metadata Manager (MDM) runs on PowerFlex storage-only nodes. SDR is supported on PowerFlex storage-only nodes with a dual CPU.

Management Interfaces Overview

To Wrapping this Up

Learning about Dell PowerFlex is highly valuable for IT professionals aiming to manage modern, scalable, and high-performance infrastructure. Here’s why:

Versatility:
PowerFlex supports a range of workloads, from databases and virtual machines to modern containerized applications, making it a universal solution for diverse IT environments.

Future-Proof Skills:
Software-defined storage and hyper-converged infrastructure are rapidly evolving technologies, and understanding PowerFlex positions you ahead in the shift toward next-generation data centers.

High Demand:
Many enterprises rely on PowerFlex for its scalability and performance, creating a strong demand for skilled professionals who can design, deploy, and manage it effectively.

Architectural Insights:
Learning PowerFlex gives deep insights into distributed systems, data management, and storage networking, which are core to building resilient and efficient IT ecosystems.

Career Growth:
Expertise in PowerFlex adds to your credentials in the broader Dell Technologies ecosystem, opening doors to system administration, cloud architecture, and IT consulting roles.

Mastering PowerFlex equips you with the knowledge and skills to excel in today’s IT landscape, where flexibility, scalability, and performance are key.