FlashArray-Implementation-Specialist Pure Storage Certified FlashArray Implementation Specialist (FAIS)

The FlashArray//XR4 introduces a new chassis layout and PCIe slot numbering scheme compared to previous generations. For expansion connectivity, specific slots are designated for the backend SAS or Ethernet/RoCE fabric cards that connect to DirectFlash Shelves.

According to the //XR4 hardware guide and expansion best practices, PCIe slot 3 is the designated location for the additional expansion interface card required when adding a second DirectFlash Shelf (or for specific shelf configurations). Slots 0 and 1 are often reserved for host I/O or other functions, and slot numbering/priority is strict to ensure the BIOS and Purity software correctly recognize the card function.

Installing the card in the wrong slot (like slot 0 or 4, if those are reserved for other uses or primary I/O) could result in the shelf not being detected, the array failing to boot, or suboptimal performance due to PCIe lane allocation. Therefore, the engineer must install the DFS expansion card into PCIe slot 3 and cable the second shelf to the ports on that specific card to ensure a supported and functional configuration.

In the architectural evolution from FlashArray//XR2 and //XR3 to the FlashArray//XR4, Pure Storage made significant changes to the controller's rear panel and I/O design to accommodate higher performance and PCIe Gen 4 capabilities. One of the most critical changes for an Implementation Engineer to plan for during a hardware Non-Disruptive Upgrade (NDU) is the removal of the onboard, default iSCSI ports that were present on previous generations. On //XR2 and //XR3 controllers, there were onboard Ethernet ports often used for iSCSI host connectivity without requiring a discrete PCIe adapter. However, the //XR4 controller design removes these dedicated onboard iSCSI ports to streamline the motherboard design and shift host I/O strictly to PCIe add-in cards. The //XR4 retains onboard ports specifically for Management (Mgmt) and Replication connectivity, ensuring that administrative access and array-to-array replication can still be maintained without additional hardware. Consequently, if a customer wasrelying solely on the onboard ports for iSCSI traffic on their legacy //XR2 or //XR3, the Bill of Materials (BOM) for the upgrade to //XR4 must include discrete Ethernet/iSCSI PCIe cards to migrate those connections. Failure to identify this architectural difference during the pre-upgrade inventory can result in a loss of host connectivity or an inability to cable the new controllers correctly, as the expected physical ports simply will not exist on the new chassis