Pass FlashArray-Implementation-Specialist Exam Guide

FlashArray performance and capacity management rely on "Write Groups"—logical groupings of drives that Purity uses to stripe data. A "Wide Write Group" typically consists of roughly 20 drives and offers better performance and capacity efficiency than smaller groups. However, Purity generally requires write groups to be contained within a single physical enclosure (chassis or shelf) to maintain failure domain boundaries and performance predictability.

In this scenario, the customer wants the new 91TB pack to form a wide write group. The chassis already has a 91TB group and a 45TB group. The shelf has one 45TB group. To create a wide write group with the new 91TB pack, it is best to pair it with an existing matching or compatible group in the same enclosure. Since the chassis is full (20 drives), you cannot simply add the new pack there without moving something.

The correct procedure is tomove the 45TB write group from the chassis to the shelf. This frees up 10 slots in the chassis. The shelf now holds two 45TB groups (which is valid). The chassis now has the original 91TB group and 10 empty slots. The engineer can then install the new 91TB data pack into those empty chassis slots. Purity will then be able to merge or manage these two 91TB packs (the existing one and the new one) as a highly efficient configuration, potentially forming the requested wide write group or at least balancing the high-capacity drives within the controller chassis where bandwidth is highest. This physical rearrangement is necessary because write groups cannot span across the chassis-shelf interconnect.

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While modern FlashArrays (like the XR4 and XL series) primarily use NVMe-oF/RoCE for backend connectivity, specific configurations or legacy support scenarios may still require aSAS HBA(Serial Attached SCSI Host Bus Adapter), for example, when connecting to older SAS-based expansion shelves during a migration or hybrid configuration.

ForR4B revision controllers(a specific hardware revision of the Gen 4 controller), the strict hardware addressing map requires that any SAS HBA be installed inPCIe Slot 1.

Slot 1provides the specific PCIe lane routing and BIOS interrupts required for the legacy SAS controller to be recognized and function without conflicting with the native NVMe fabric.

Installing the card in Slot 0 (typically reserved for RoCE/Ethernet backend) or Slot 4 would likely result in the card being ignored by Purity or causing boot errors due to resource conflict.

The upgrade from a FlashArray//XR4 to a FlashArray//XL is a specific "Data-in-Place" hardware migration that utilizes thepurewes(Pure Workflow Execution Service) utility to orchestrate complex steps. One of the most critical steps involves stopping the Purity software stack on the controller that is about to be removed (CT0) to ensure a clean failover and data flush to the surviving controller.

The correct command syntax ispurewes controller disable --purity --verify-mode secondary --verify-array ARRAY_NAME ct0.

purewes controller disable: Initiates the shutdown of the controller's services.

--purity: Specifies that the Purity software stack should be stopped (not just the hardware).

--verify-mode secondary: This is a crucial safety check. It ensures the commandonlyexecutes if CT0 is currently the Secondary controller. If CT0 were Primary, running this command without a failover first would cause an outage.

--verify-array: Confirms the action is being taken on the correct target array.

This command sequence ensures the controller is safely quiesced before the Implementation Engineer physically removes it from the chassis.

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The FlashArray//XL series has a specific, validated slot population rule for its PCIe cards to ensure optimal performance and thermal management. For a standard Fibre Channel (FC) configuration on aFlashArray//XLR5, the factory default shipment includes a specific arrangement of host I/O cards and offload engines.

The correct default configuration is:

PCIe Slot 3:4-Port 32Gb FC card.

PCIe Slot 5:2-Port 32Gb FC card.

PCIe Slot 6:DirectCompress Accelerator (DCA).

This layout (Option B) adheres to the //XL's architecture where specific slots are prioritized for frontend host I/O (like slots 3 and 5) and others for offload functions or backend connectivity. Implementation Engineers must verify cards are in these exact slots during the visual inspection. If cards are moved to incorrect slots (like slot 1 or 4 for primary FC in this specific config), the array may not boot or may fail to initialize the FC services correctly due to BIOS enumeration orders.

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