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Zorluk: ZorStorage Devices and Interfaces

A system technician installs a passive quad-slot M.2 NVMe PCIe x16 expansion card containing four identical NVMe solid-state drives into a motherboard's primary PCIe 4.0 x16 slot. Upon booting the computer, only the SSD installed in the first slot of the expansion card is recognized by the UEFI firmware and operating system. The remaining three SSDs fail to appear in storage management tools. Which motherboard UEFI configuration setting must be enabled to allow all four NVMe drives to be detected?

  1. PCIe slot bifurcation (configuring the x16 slot to operate in x4/x4/x4/x4 mode)Cevap
  2. B
    SATA host controller mode (switching the storage controller from AHCI mode to RAID mode)
  3. C
    NVMe Host Memory Buffer (allocating system DRAM shared cache memory to the controller)
  4. D
    Resizable BAR and Above 4G Decoding (enabling extended memory-mapped I/O space)

Cevap

PCIe slot bifurcation (configuring the x16 slot to operate in x4/x4/x4/x4 mode)
Passive multi-drive M.2 carrier cards do not include expensive onboard PCIe switch chips. Instead, they require the motherboard to support PCIe slot bifurcation—a feature that dynamically divides a physical x16x16 slot into four independent x4x4 lanes (x4/x4/x4/x4x4/x4/x4/x4). Once bifurcation is enabled in UEFI, the motherboard controller can negotiate separate links with each of the four NVMe drives.

Adım Adım Çözüm

1
Analyze the hardware architecture of the expansion card
Identify that a passive quad-M.2 PCIe card lacks a hardware PCIe bridge/switch ASIC chip.
Without an onboard switch chip, each M.2 slot requires dedicated PCIe lanes directly from the motherboard CPU/chipset.
2
Determine the default behavior of an un-bifurcated PCIe x16 slot
By default, a motherboard sends all 16 PCIe lanes to the first device/controller detected on the card slot.
The expansion card's first slot receives the initial 4 lanes, while the remaining 12 lanes are unassigned to the other slots.
3
Select the correct motherboard firmware feature to resolve lane distribution
Enable PCIe slot bifurcation in UEFI setup, dividing the slot into x4/x4/x4/x4x4/x4/x4/x4 mode.
Bifurcation explicitly instructs the motherboard root complex to treat the single x16x16 slot as four distinct x4x4 controllers, enabling recognition of all four NVMe SSDs.

Anahtar Kavram

PCIe Slot Bifurcation and M.2 NVMe Carrier Cards
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Konular

Storage Devices and Interfaces

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