The PowerFlex cluster is built from eight bare-metal nodes that are configured in the hyperconverged deployment model. The PowerFlex cluster uses its Storage Data Server (SDS) component to provide a resilient storage layout. SDS is a service that aggregates raw local storage of all the participating nodes and presents a high-end virtual storage system. SDSs may use SSDs, PCIe-based flash, spinning media, RAID controller write cache, available RAM, or any combination thereof to provide fault tolerance system. A collection of SDSs forms the PowerFlex storage persistence layer. SDS components can communicate directly with each other, and collections of SDSs are fully meshed.

Each node is populated with ten 1.92 TB SSD drives. Thus, a total of 80 disks from eight nodes are aggregated to make one resilient storage pool, and the usable storage volumes are carved out as required. SDSs are optimized for rebuild, rebalance, and I/O parallelism. The user data layout among SDS components is managed through storage pools, protection domains, and volumes.

A protection domain is a set of SDSs configured into separate logical groups. An SDS may belong to only a single protection domain. Protection domains can be used to divide a PowerFlex system into smaller logical systems. Protection from node, device, and network connectivity failure is managed with node-level granularity through protection domains.

Client volumes that are used by the application workloads are provisioned from the storage pool. Storage pools are used to logically aggregate types of storage media at drive-level granularity. Storage pools can provide varying levels of storage service that is distinguished by capacity and performance. The PowerFlex storage layout for this reference architecture is as follows:

• A single protection domain is created from eight PowerFlex nodes for the SQL Server project.
• A single storage pool is created using all of the SSDs installed in each node that is a  member of the protection domain and then persistent client volumes are created from this storage pool.
• All the SQL Server pod volumes are provisioned by PowerFlex software from the storage pool as requested by the PowerFlex CSI driver.

All participating nodes also have the Storage Data Client (SDC) installed. The SDC component of PowerFlex software can access the volume that is created from the storage pool hosted on the SDS nodes. In this reference architecture, SDC communicates with PowerFlex CSI driver to store data into the PowerFlex system.

For detailed information about PowerFlex nodes and VM configuration, see Appendix Configuration details.