The upgrade from a FlashArray//M20R2 to an //X20R3-EMEZZ involves a shift in back-end storage connectivity from SAS to NVMe-oF (RoCE). Direct Flash Modules (DFMs) are NVMe-based and require a DirectFlash Shelf (DFS) for housing and connectivity. The existing SAS shelves are incompatible with DFMs. Therefore, to add a new DFM data pack, a new DirectFlash Shelf must be installed and connected to the //X20R3 controllers. The term "DFM Swing shelf" refers to this new shelf that is added to facilitate the expansion with the new DFM technology.

B. SAS Swing shelf: This is incorrect because SAS shelves are designed for SAS-based flash modules, not the NVMe-based Direct Flash Modules (DFMs) the customer wants to add.

C. 4-port ETH card: While Ethernet ports are used to connect DirectFlash Shelves, the //X20R3 controllers have built-in 25/10GbE ports for this purpose. The primary and essential hardware required to house the DFMs is the shelf itself, not necessarily an additional network card.

1. Pure Storage FlashArray//X Hardware Guide: This document details the physical components of the FlashArray//X models. It specifies that //X R3 controllers use DirectFlash Shelves for expansion and connect to them via Ethernet (RoCE) ports, differentiating them from the SAS-connected shelves used with older models like the //M-series. (See sections on "FlashArray//X R3 Chassis" and "DirectFlash Shelf").

2. Pure Storage FlashArray//X Family Datasheet: This datasheet confirms that FlashArray//X R3 models utilize DirectFlash Shelves for capacity expansion. It states, "Expand capacity with DirectFlash shelves connected via 50 Gb/s RoCE (RDMA over Converged Ethernet)." This explicitly links the new controller technology to the required shelf type. (See section "FlashArray//X Specifications").

3. Pure Storage Best Practices and Implementation Guides: Official implementation guides for controller upgrades (e.g., from //M to //X series) outline the procedure for introducing new hardware. These guides describe the process of adding a new NVMe-based shelf (a "swing shelf") to either migrate data from older SAS shelves or to expand capacity with the newer DFM technology post-upgrade.