Doca Sta

DOCA STA (Storage Target Acceleration)

Examples

• "Offload the nvmf target onto the DPU." — this is in scope. Stand up doca_sta + subsystem/namespaces; do not rewrite the initiator stack here.

• "Identify Controller times out over RoCE." — check doca_sta_cap_is_supported and queue sizing before changing backend disks.

Instructions

Follow Loading order below. Open the tasks companion for configure / target / debug. Open the capabilities companion for queue limits and NVMe-oF caps. Do not open every companion file.

Where to start: This skill assumes DOCA is already installed and the user is doing hands-on NVMe-over-Fabrics storage-target work on a BlueField-class device with DOCA. Open the tasks companion if the user wants to do something (configure / modify / build / run / test / debug); open the capabilities companion when the question is what can DOCA STA express on this version. If the user has not installed DOCA yet, route to doca-setup/SKILL.md first. If the user is asking "is this an NVMe-oF initiator/host transport?", the answer is no — doca-sta accelerates the target side: it presents NVMe-oF doca_sta_subsystem targets backed by local NVMe-PCI disks; the model lives in the capabilities companion.

Example questions this skill answers well

The CLASSES of DOCA STA questions this skill is built to answer, each with one worked example. The agent should treat the class as the load-bearing piece — the worked example is a single instance.

• "How do I bring up an NVMe-oF target that uses the BlueField to accelerate the storage data path?" — worked example: "define a doca_sta_subsystem (NQN) with one namespace backed by a local NVMe-PCI disk (doca_sta_be) and accept NVMe-over-RDMA connections from a remote initiator". Answered by the target-model-and-lifecycle workflow in the tasks companion + the capabilities companion target-object table.

• "Can this BlueField accelerate an NVMe-oF target at all?" — worked example: "my data center is RoCE end-to-end; does this device support DOCA STA target acceleration?". STA transport is RDMA-only (there is no NVMe-over-TCP path). Answered by the capability-query rule (doca_sta_cap_is_supported against a doca_devinfo) in the capabilities companion

  • the discovery step in the tasks companion.

• "How deep can I size my I/O queues, and how many I/O queues per connection?" — worked example: "I want 16 I/O queues at depth 1024 each — does this device support that?". Answered by the queue-sizing capability surface in the capabilities companion

  • the queue-sizing step in the tasks companion which gates on the matching doca_sta_get_max_* query (e.g. doca_sta_get_max_qps, doca_sta_get_max_io_queue_size).

• "Which other DOCA libraries do I need alongside doca-sta?" — worked example: "do I need doca-rdma directly, or does doca-sta hide it from me?". Answered by the substrate-library rule in the capabilities companion

  • the env-prep checklist in the tasks companion step 1, which routes the steering side to doca-flow/SKILL.md and the RDMA substrate to doca-rdma/SKILL.md.

• "Is this STA capability available on my installed DOCA?" — worked example: "is STA target acceleration supported on this BlueField + DOCA version?". Answered by the version-and-device overlay in the capabilities companion, which cross-links the canonical detection chain in doca-version/SKILL.md and adds the STA-specific cap-query rule (pkg-config --modversion doca-sta is the build-time anchor; the runtime doca_sta_cap_is_supported query is the truth).

• "What does this DOCA_ERROR_* from a STA call mean and which layer caused it?" — worked example: "DOCA_ERROR_NOT_PERMITTED when opening the doca_dev". Answered by the STA overlay on the cross-library taxonomy in the capabilities companion

  • the layered ladder in the tasks companion that escalates to doca-debug/SKILL.md.

A Connect handshake that never completes is usually not an STA bug. It is the single most common first-app failure, and the answer is to walk the three preconditions in the capabilities companion before any code change: the RDMA substrate resolves on the chosen device, the doca_dev was opened with sufficient permission, and — most often the culprit — a DOCA Flow rule actually steers the matching NVMe-oF 5-tuples to this instance's queues. The steering side belongs to doca-flow/SKILL.md; route it rather than inventing a doca_sta_* steering call, and do not start by auditing STA lifecycle or target-side code. The same applies to an Identify Controller that times out over RoCE.

DOCA_ERROR_IO_FAILED on a per-I/O completion is a transport error, not a target-side STA bug — a link drop, RDMA peer disconnect, firmware fault, or peer controller reset. Being able to ping the target does not exclude any of these. Do not retry blindly and do not change STA code first: capture dmesg and route to doca-rdma/SKILL.md, per the tasks companion.

Audience

This skill serves external developers building NVMe-over-Fabrics storage targets that consume DOCA STA on BlueField — i.e., users whose code calls doca_sta_* (directly in C/C++, or through FFI/bindings from another language) to accelerate the target-side data path of an NVMe-oF target on the BlueField hardware: presenting doca_sta_subsystem targets (NQN + namespaces) backed by local NVMe-PCI disks (doca_sta_be) to remote initiators over RDMA. The skill is not for NVIDIA developers contributing to DOCA STA itself, and it is not for initiator/host-side NVMe stacks.

Language scope. DOCA STA ships as a C library with pkg-config module name doca-sta. DOCA STA ships no public samples — the public packages install no samples/doca_sta/ directory — so the worked examples in the tasks companion build against the public headers directly rather than modify a shipped sample. C and C++ consumers are the canonical case. Other-language consumers (Rust, Go, Python, …) consume the same *.so through FFI or language-specific bindings; the skill's contribution in that case is to keep the target-model, lifecycle, capability-discovery, queue-pair shape, substrate-dependency, and error-taxonomy guidance language-neutral, and to route the agent to the public C ABI as the authoritative surface that any wrapper will eventually call.

When to load this skill

Load this skill when the user is doing hands-on DOCA STA work, in any language. Concretely:

• Initializing a doca_sta instance on a doca_dev opened against a BlueField PF / SF and configuring the NVMe-oF target subsystems before doca_ctx_start().

• Defining target resources — doca_sta_subsystem (NQN + namespaces) and doca_sta_be backend controllers (local NVMe-PCI disks) — and accepting NVMe-oF connections (admin queue plus N I/O queues per connection) on the target side as remote initiators connect over RDMA CM.

• Reading or setting STA properties via the doca_sta_set_* family, checking device support via doca_sta_cap_is_supported, and querying sizing limits via the doca_sta_get_max_* family (max I/O queue depth, max number of queue pairs, max I/O size, max subsystems, max namespaces per subsystem, max backends).

• Wiring the NVMe-over-RDMA transport — STA's only transport; it lands on the doca-rdma substrate and uses RDMA CM for connection establishment — for the target's I/O queues.

• Wiring DOCA Flow rules so that NVMe-oF traffic actually reaches the STA-managed queues — the steering boundary is doca-flow, not doca-sta.

• Debugging a DOCA_ERROR_* returned from a STA call (lifecycle vs. capability vs. transport-layer I/O failure vs. driver-below) and the per-queue events on the DOCA Core progress engine.

• Designing or extending non-C bindings (Rust, Go, Python, …) that wrap the DOCA STA C ABI — for the lifecycle, queue-pair, cap-query, and substrate-dependency rules the wrapper must honor.

Do not load this skill for general DOCA orientation, install of DOCA itself, raw RDMA data movement (use doca-rdma/SKILL.md), raw packet I/O on Ethernet queues (use doca-eth/SKILL.md), flow-rule programming (use doca-flow/SKILL.md), or initiator/host-side NVMe stack development (SPDK or kernel-nvme own that, not this skill). For DOCA documentation orientation, use doca-public-knowledge-map/SKILL.md.

What this skill provides

This is a thin loader. The body keeps only the orientation needed to pick the right next file. The substantive STA-specific material lives in two companion files:

• the capabilities companion — what DOCA STA can express on this version: the target object model (doca_sta_subsystem / namespaces / doca_sta_be backend NVMe-PCI disks), the NVMe queue-pair shape (admin queue + I/O queues over RDMA), the RDMA-only transport, the capability-query surface (doca_sta_cap_is_supported plus the doca_sta_get_max_* sizing queries), the STA error taxonomy (mapped onto the cross-library DOCA_ERROR_* set), the observability surface (per-queue progress engine events, capability snapshots), and the safety policy that gates substrate-library, permission, and steering preconditions.

• the tasks companion — step-by-step workflows for the six in-scope STA verbs: configure, modify, build, run, test, debug. Plus a Deferred task verbs block that points out-of-scope questions at the right next skill, and a Command appendix of the recurring commands the agent reaches for.

The skill assumes a BlueField (with DOCA installed at the standard location) plus a remote NVMe-oF initiator reachable on the fabric to connect into the accelerated target, and one or more local NVMe-PCI disks to back the target's namespaces. It does not cover installing DOCA — that path goes through doca-setup/SKILL.md. It does not cover initiator/host-side NVMe stacks (SPDK bdev_nvme, kernel nvme host) or NVMe protocol semantics above the accelerated target data path — those are out of scope.

What this skill deliberately does not ship

This skill is agent guidance, not a samples or templates bundle. To keep the boundary clean, it deliberately does not contain — and pull requests should not add:

• Pre-written DOCA STA application source code, in any language. DOCA STA ships no public samples — there is no /opt/mellanox/doca/samples/doca_sta/ directory. The authoritative surface is the public headers under $(pkg-config --variable=includedir doca-common) plus the public DOCA STA guide; the agent builds against those directly rather than modifying a shipped sample, per the the tasks companion workflow.

• Initiator/host-side NVMe stack glue. SPDK bdev_nvme, the kernel nvme host, and any initiator-side NVMe stack are upstream projects out of scope for this skill — DOCA STA is target-side acceleration, not an initiator transport provider.

• Standalone build manifests (meson.build, CMakeLists.txt, Cargo.toml, …) parked inside the skill. The agent constructs the build manifest in the user's project directory against the user's installed DOCA, where pkg-config --modversion doca-sta is the source of truth.

• A samples/, bindings/, or reference/ subtree of any kind. A mock or incomplete artifact in this skill's tree, even one labeled "reference", is misleading: users will read it as buildable.

Loading order

1. Read this skill first to confirm the user's question is in scope.

2. For the STA capability matrix, the target object model, queue-pair shape, RDMA-only transport, capability-query rules, error taxonomy, observability, and safety policy, see the capabilities companion.

3. For step-by-step workflows — configure, modify, build, run, test, debug — see the tasks companion.

Both companion files cross-link to each other, doca-version/SKILL.md for the canonical version-handling rules, doca-rdma/SKILL.md for the RDMA substrate that NVMe-over-RDMA transport lands on, doca-flow/SKILL.md for the steering rules that direct NVMe traffic to STA-managed queues, and doca-public-knowledge-map/SKILL.md whenever the right answer is "look it up in the public docs or the installed package layout" rather than "STA-specific guidance".

Related skills

• doca-public-knowledge-map/SKILL.md — the routing table for every public DOCA documentation source and the on-disk layout of an installed DOCA package. The STA URL slug is DOCA-STA.

• doca-setup/SKILL.md — env preparation, install verification, BlueField mode checks, and the permission / group-membership requirements for opening a doca_dev. This skill assumes its preconditions are satisfied.

• doca-version/SKILL.md — canonical DOCA version-handling rules. This skill's ## Version compatibility cross-links the four-way match rule and adds only the STA-specific overlay (STA target-acceleration availability windows, NVMe-oF feature-set device-conditional support).

• doca-structured-tools-contract/SKILL.md — the bundle's structured-tools precedence rule (detect / prefer / fall back / report). The Command appendix in the tasks companion honors this contract.

• doca-programming-guide/SKILL.md — general DOCA programming patterns shared by every library: the canonical pkg-config + meson build pattern, the universal modify-a-shipped-sample first-app workflow, the universal lifecycle, the cross-library DOCA_ERROR_* taxonomy, and the program-side debug order. This skill layers STA specifics on top.

• doca-rdma/SKILL.md — the RDMA substrate that NVMe-over-RDMA transport lands on. STA hides most of the RDMA queue-pair details from the consumer, but the user still needs doca-rdma linked in and the device's RDMA capabilities discoverable for the NVMe-over-RDMA path to work.

• doca-eth/SKILL.md — the queue-pair shape that STA's per-connection queue model echoes. Reach here if the user is asking general questions about how DOCA exposes queue-pairs that don't have an STA-specific answer.

• doca-flow/SKILL.md — the steering surface that decides which NVMe-oF packets land on which STA-managed queue. DOCA STA does not program steering itself; an NVMe-oF target whose connections never come up is often a missing or wrong Flow rule, not a STA bug.

• doca-debug/SKILL.md — the cross-cutting debug ladder (install / version / build / link / runtime / program / driver). STA-specific debug (transport-type mismatches, queue-depth oversize, IO-failed transport errors) overlays on top of that ladder.