{
  "slug": "pcie-switch",
  "term": "PCIe switch",
  "aliases": [
    "PCI Express switch"
  ],
  "definition": "A PCIe switch connects an upstream PCI Express path to multiple downstream ports so that several devices can share the upstream connection.",
  "note": "A storage adapter may use a PCIe switch to connect several SSDs without asking the host to bifurcate its slot. The cited switched dual-drive adapter documents this arrangement. It does not qualify other cards or guarantee their performance. [switch]\n\nAn endpoint's link width is not a dedicated end-to-end bandwidth reservation. Inspect upstream links and competing traffic as well as each SSD connection; Linux's minimum-link calculation identifies a link-configuration ceiling along the traversed upstream PCIe path, not unused bandwidth or measured SSD throughput. [linux]\n\nPeer-to-peer DMA also needs cooperating drivers and a compatible route. Linux v6.12 documents provider, client and orchestrator roles; its compatibility check allows a common root port or specifically allowlisted host bridges. A switch alone does not establish application support. [p2p]",
  "status": "shipping",
  "advantages": [
    "Can support a multi-SSD adapter without host bifurcation, as documented for the named switched design. [switch]"
  ],
  "limitations": [
    "A switch does not create additional capacity on a shared upstream link. [linux]",
    "Do not infer hot-plug, boot or cross-platform support from the presence of a switch.",
    "Do not infer peer-to-peer DMA support from the switch or link width alone. [p2p]"
  ],
  "related": [
    "pcie-storage",
    "pcie-lanes",
    "pcie-bifurcation",
    "nvme"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "linux",
      "title": "Linux PCI support library: pcie_bandwidth_available; upstream path and limiting link.",
      "url": "https://docs.kernel.org/driver-api/pci/pci.html#c.pcie_bandwidth_available",
      "accessed": "2026-10-18"
    },
    {
      "id": "switch",
      "title": "StarTech PEX8M2E2: ASM2824 switched dual-SSD adapter; no host bifurcation required for this product.",
      "url": "https://media.startech.com/cms/pdfs/pex8m2e2_datasheet.pdf",
      "accessed": "2026-11-02"
    },
    {
      "id": "p2p",
      "title": "Linux v6.12: PCI Peer-to-Peer DMA Support; hierarchy, compatible providers and driver roles.",
      "url": "https://www.kernel.org/doc/html/v6.12/driver-api/pci/p2pdma.html",
      "accessed": "2026-11-03"
    }
  ],
  "updated": "2026-11-03",
  "provenance": [
    "The named example is StarTech PEX8M2E2 with ASM2824. Source-based topology description, not a switch benchmark or platform certification."
  ]
}