The FlashArray//XL supports 0 (zero) SAS expansion shelves for permanent capacity.

Architecture: The FlashArray//XL is architected exclusively for NVMe storage media. Its backend connectivity utilizes 100GbE RoCE (RDMA over Converged Ethernet) to connect to DirectFlash Shelves (DFS) . It does not possess the legacy SAS controllers or ports required to drive SAS expansion shelves.

Migration Exception: While a "SAS Swing Shelf" (containing legacy SSDs from an older array) might be temporarily attached during a specific Data-in-Place upgrade migration scenario, this is a transient state. In terms of supported operational configuration for storage capacity, the limit is zero. The platform relies entirely on DirectFlash Modules in the chassis and external DirectFlash Shelves.

Contrast: Older generations (FlashArray//M, FlashArray//X R1/R2) supported SAS shelves, but the //XL platform eliminates this protocol entirely in favor of end-to-end NVMe.

When executing a capacity migration or consolidation on a highly utilized Pure Storage FlashArray (such as an //X90 Gen 2 at 90% capacity), physical and logical space limitations dictate the required procedure. The FlashArray chassis only contains 24 front-facing capacity drive bays. In this scenario, the chassis is fully populated with 10 drives in slots 0-9 and 14 drives in slots 10-23.

Because all physical chassis slots are occupied, there is nowhere to physically insert the new 91TB (10 x 9.1TB) DirectFlash Modules. Furthermore, because the array is at 90% capacity, there is insufficient logical free space remaining to evacuate the 22TB data pack into the existing 63TB pack's free capacity. Standard evacuation requires the system to non-disruptively move data off the target drives before they can be safely removed, which is mathematically impossible here without external capacity.

To resolve this, the officially supported method is to install a temporary "swing shelf" (Option B). A swing shelf acts as a temporary expansion vessel. The Implementation Engineer physically racks the swing shelf, connects it to the array, and inserts the new 91TB data pack into it. Purity can then safely evacuate the data from the old 22TB chassis data pack onto the new drives in the swing shelf. Once the evacuation completes, the old drives are decommissioned and removed, the new 91TB drives are seamlessly relocated into the chassis slots 0-9, and the swing shelf is removed and returned.

When adding external capacity to a Pure Storage FlashArray via a DirectFlash Shelf (DFS), Implementation Engineers must adhere to strict, high-speed networking port assignments to ensure maximum backend throughput. Unlike older Fibre Channel or basic SAS expansion shelves that use dedicated SAS cabling, a modern DFS relies on massive 50GbE or 100GbE bandwidth using the NVMe-oF (RDMA over Converged Ethernet - RoCE) protocol to maintain NVMe-level speeds across the external fabric.

According to the official FlashArray//XR4 Port Usage and Definitions hardware matrix, the onboard 100GbE RoCE ports explicitly dedicated to the first loop of a DirectFlash Shelf are physically located on the controllers and identified within the Purity operating system as ETH 18 and ETH 19 .

These specific ports are hardware-optimized to handle the extreme backend IOPS generated by the external DirectFlash Modules communicating back to the primary chassis. Utilizing standard 1GbE/10GbE management/replication ports (such as ETH 0/1) or other generic PCIe Ethernet host interfaces (such as ETH 10/11) is unsupported for the primary DFS backend loop. Plugging the shelf into the wrong ports will result in cabling validation failures during the hardware_check.py execution, preventing the new capacity from being recognized by the array.

To verify the history and transmission status of Phonehome log bundles, the correct command is purearray phonehome --list .

Before starting a controller upgrade (NDU), it is mandatory to ensure that the array can successfully transmit diagnostic data to Pure Storage. This allows Support to review the "pre-flight" checks and ensures that if an issue occurs during the upgrade, logs will be available for triage.

Usage: Running purearray phonehome --list displays a table of recent log bundles generated by the system.

Verification: The Engineer must look at the Status column for the most recent entries. A status of "uploaded" confirms that the array has successfully connected to the Pure Storage cloud and transferred the data. If the status is "queued" or "failed," the upgrade should not proceed until network connectivity (firewall/proxy) is resolved. Options A and C are incorrect CLI syntax for this specific verification task.

A "4X Module" kit is specifically designed to widen an existing write group (RAID set).

Write Group Geometry: In standard FlashArray//X configurations, DirectFlash Modules (DFMs) operate in "Write Groups" (typically 10 modules wide for a standard data pack). However, to offer more flexible entry points or capacity expansion options, Pure Storage allows configurations that start with smaller write groups (e.g., 6 modules).

Widening: When a customer wants to expand capacity or performance on these smaller configurations without adding a full new 10-pack, they can purchase a widening kit (in this case, 4 modules).

Process: The Implementation Engineer installs these 4 modules into the empty slots. The Purity operating system then logically integrates these new drives into the existing narrow write group, "widening" it to the standard width (e.g., 6 + 4 = 10). This operation redistributes parity and data across the full set of 10 drives, improving performance and efficiency.

When implementing FA File services (Pure Storage's file services protocol support), the array must integrate with the customer's existing directory infrastructure (like Active Directory) for user authentication and permission management. By default, the FlashArray utilizes its management interface to perform DNS resolution and establish communication with domain controllers.

This design choice simplifies initial deployment because the management network is typically already configured with access to core infrastructure services like DNS and NTP. While the filevip (File Virtual IP) and its associated virtual interfaces (vif) are used for actual SMB/NFS data traffic between clients and the array, the control plane traffic for directory services and authentication lookups is routed through the management port (ct0.eth0/ct1.eth0 or the virtual management IP).

It is critical for Implementation Engineers to verify that the management network has the necessary firewall rules and routing to reach the customer's domain controllers and DNS servers. If the management interface is isolated on a dedicated out-of-band network without access to these services, the FA File directory service configuration will fail, even if the data interfaces (filevip) are correctly cabled and IP'd.

=========

To specifically verify the shelf cable connections and validate the SAS topology during an installation, the correct command is storage_view.py config .

While standard Purity CLI commands like purehw list (Option B) can show the presence and general status of enclosures, they often do not provide the granular, low-level details of the SAS cabling map required to troubleshoot or verify physical redundancy paths (Side A vs. Side B connectivity).

storage_view.py is a specialized Python utility script included in the Purity operating system, primarily intended for use by Implementation Engineers and Support. Running storage_view.py config (or similar arguments like enclosures) outputs a visual or tabular representation of the backend cabling, explicitly showing how the controllers are chained to the expansion shelves. This allows the engineer to confirm that the cabling matches the strict "stacking" rules (e.g., verifying that the SAS loops are closed and redundant) and to identify issues like cross-cabling or disconnected paths that a simple "status=healthy" flag might miss during the initial build.

The correct pre-implementation step is to make space in the rack where the chassis is located .

Cabling Standards: DirectFlash Shelves (DFS) connect to the FlashArray via RoCE (RDMA over Converged Ethernet) using QSFP28 cables. The standard cabling kits provided by Pure Storage typically include short-range Passive DACs (e.g., 1m to 3m) or short Active Optical Cables (AOCs).

Distance Constraint: A distance of 6 meters between racks usually exceeds the length of standard included cables and introduces complexity regarding cable management, signal integrity, and "span" policies. While custom long-range optical cables exist, they are not standard stock and relying on ordering a non-standard "7m" cable (Option B) is a risk.

Best Practice: Pure Storage installation guides explicitly recommend installing expansion shelves in the same rack and contiguous to the controller chassis whenever possible. This ensures optimal airflow, ease of serviceability, and adherence to standard cabling schematics. Moving the entire controller chassis (Option C) is a disruptive and heavy-lift operation, whereas clearing 3U of space (Option A) is the standard facility preparation task required for a successful deployment.

For PhoneHome (telemetry) and Remote Assist (support tunnels) to function correctly, TCP Port 443 (HTTPS) must be open for outbound traffic from all management ports (CT0.ETH0, CT1.ETH0, and the Virtual Management IP).

Pure Storage utilizes a secure, encrypted connection to communicate with the Pure1 Cloud and Support infrastructure.

PhoneHome: The array sends logs and heartbeat data to purestorage.com (and associated subdomains) via HTTPS over Port 443. If this port is blocked, the array cannot report its health status, preventing proactive support.

Remote Assist: This feature creates a reverse SSH tunnel encapsulated over HTTPS (websocket or similar secure transport) to allow Pure Support to remotely log in. It initiates the connection outbound to the support relay servers on Port 443.

Option A (Port 80) is generally not used for secure management traffic in modern configurations, often only serving as a redirect. Option C (Port 123) is required for NTP (Network Time Protocol) synchronization, which is critical for logs but is not the transport port for the PhoneHome/Remote Assist data stream itself. Therefore, verifying firewall rules for Port 443 is the primary troubleshooting step.

To perform parallel evacuation of multiple SAS shelves , the FlashArray must be running Purity//FA 6.0 or higher.

Prior to Purity version 6.x, the shelf evacuation process (used during capacity consolidation or shelf retirement) was a serialized operation. An Implementation Engineer had to issue the evacuation command for one shelf, wait for all data to move to other storage within the array, and physically remove that shelf before starting the process for the next one. This could be time-consuming for large clusters of legacy SAS shelves.

With the release of Purity//FA 6.0, Pure Storage introduced significant enhancements to data mobility and background operational efficiency, including the ability to issue evacuation commands for multiple external shelves simultaneously. The system's intelligent scheduler manages the I/O bandwidth to ensure that the parallel data movement does not impact frontend host performance. While having sufficient free space (Option C) is logically necessary to hold the evacuated data, the specific functional capability to trigger concurrent evacuations is a software feature tied strictly to the Purity 6.x code base. Option B is irrelevant to the software capability of the array.