How to Read and Interpret VRCP DrvInfo LogsVRCP DrvInfo logs are a valuable source of driver- and device-level telemetry used by system administrators, firmware engineers, and support teams to diagnose hardware issues, analyze performance, and validate configurations. This guide explains what DrvInfo logs typically contain, how to read their entries, how to map fields to real-world behavior, and practical troubleshooting workflows.
What is VRCP DrvInfo?
VRCP DrvInfo is a structured diagnostic output produced by VRCP-capable drivers and controller firmware. It exposes driver state, device capabilities, error counters, firmware versions, and runtime metrics in a format intended for troubleshooting and automated analysis. While formats vary by vendor and version, common elements are consistent across implementations.
Typical DrvInfo log structure
A DrvInfo log usually contains these sections:
- Header — timestamp, source, driver and firmware versions.
- Device descriptors — model IDs, serial numbers, supported features.
- State information — driver state machine, current operational mode.
- Counters and metrics — I/O counts, latency stats, error rates.
- Error and event records — recent faults, stack traces, error codes.
- Configuration and capabilities — enabled features, negotiated settings.
- Diagnostics — self-test results, memory/CPU usage snapshots.
Example (conceptual):
Timestamp: 2025-08-30T14:22:10Z Driver: vrdrv 3.4.1 Firmware: v2.1.7 Device: VRX-2000 SN: ABC12345 State: OPERATIONAL IO: total=125678 read=78945 write=46733 Errors: CRC=2 Timeout=5 LinkDown=0 Config: jumbo=true flowctrl=off speed=10Gbps LastEvents: - 2025-08-30T14:20:05Z ERR Timeout 0x1A - 2025-08-30T14:21:40Z WARN HighLatency 250ms Key fields and what they mean
- Timestamp — when the snapshot was taken. Use to correlate with other logs or alerts.
- Driver/Firmware versions — essential for known-bug mapping; always note these when opening support cases.
- Device identifiers (model, serial) — map logs to hardware inventory.
- State — tells whether device is OPERATIONAL, DEGRADED, INITIALIZING, ERROR, etc. A non-OPERATIONAL state is the primary clue to investigate.
- IO counters (read/write/total) — baseline throughput and workload distribution. Sudden drops or spikes indicate issues or workload changes.
- Error counters (CRC, Timeout, LinkDown) — incremental counters; check deltas between snapshots to find when issues started.
- Latency metrics — average, p50/p95/p99; useful for spotting tail latency problems.
- Config/Caps — negotiated link speed, offloads, checksum offload, jumbo frames; mismatches between peers cause subtle failures.
- Event records — time-ordered events with severity and codes; these often include actionable error codes.
Interpreting common symptoms
-
High CRC errors:
- Likely physical layer problems — bad cable, connector, or signal integrity issue.
- Action: swap cable, inspect connectors, run physical layer diagnostics.
-
Increasing timeout counters:
- Could be congestion, overloaded device, or firmware bug.
- Action: correlate with latency and IO counters; check CPU/memory usage on the device.
-
LinkDown occurrences:
- Link flaps indicate port, transceiver, or peer problems.
- Action: check transceiver module, SFP logs, port settings (speed/duplex).
-
High write vs read imbalance:
- Reflects workload pattern; if unexpected, check application configuration or storage target health.
-
Degraded state with no obvious errors:
- Could be configuration mismatch or health-check failing.
- Action: review capability negotiation fields and recent events; compare to known-good config.
Step-by-step troubleshooting workflow
- Capture context:
- Collect DrvInfo snapshots from affected and unaffected devices, along with system/application logs and timestamps.
- Verify versions:
- Note driver and firmware versions; search release notes for fixed issues or known regressions.
- Baseline comparison:
- Compare IO counters, latency percentiles, and error counters with a known-good baseline.
- Correlate events:
- Use timestamps to find correlated events (reboots, config changes, network events).
- Isolate layers:
- Separate physical, link, transport, and application layers. Physical checks (cables, optics) are quick and often resolve CRC/flap issues.
- Reproduce in lab:
- If feasible, reproduce the issue with same driver/firmware and workload to gather deterministic traces.
- Escalate with evidence:
- When contacting vendor support, provide DrvInfo snapshots, diffs, and correlated logs; include reproduction steps and time windows.
Practical tips for reading logs faster
- Focus on deltas: compare snapshots before and after the issue rather than raw values.
- Sort events by timestamp and severity.
- Normalize counters to rates per second/minute for easier trend spotting.
- Keep a reference “golden” DrvInfo from a healthy device for quick comparison.
- Automate parsing: use scripts (Python, jq for JSON outputs) to extract key metrics and generate alerts when thresholds are crossed.
Example jq snippet for JSON-style DrvInfo:
cat drvinfo.json | jq '.device, .driver, .metrics.errors, .metrics.latency' Sample interpretation cases
Case A — Sudden latency spike:
- Findings: p99 latency jumped from 20ms to 450ms; timeout counters increased; total IO unchanged.
- Interpretation: transient congestion or processing stall. Check CPU load and any long garbage-collection or interrupts on device.
Case B — CRC errors increasing:
- Findings: CRC counter incrementing, LinkDown=0, latency normal.
- Interpretation: physical signal errors not severe enough to drop link; test cable/replace SFP.
Case C — Device in DEGRADED state with config mismatch:
- Findings: negotiated speed 1Gbps on one side, 10Gbps expected; flow control disabled.
- Interpretation: link negotiation mismatch due to mismatched settings or faulty auto-negotiation. Fix link settings or force speed.
When to open a support case
Provide DrvInfo snapshots, driver/firmware versions, timestamps, a short description of observed behavior, and steps to reproduce. Attach diffs between healthy and failing snapshots and any relevant system logs. Include captured core dumps or traces if available.
Tools and automation suggestions
- Log parsers: jq, Python scripts (pandas for trend analysis).
- Visualization: Grafana or Kibana for time-series of counters/latency.
- Alerting: threshold-based alerts on error-rate deltas and latency percentiles.
- Inventory mapping: attach DrvInfo device IDs to asset management to rapidly find affected hardware.
Summary checklist (quick reference)
- Capture DrvInfo + system logs with timestamps.
- Note driver/firmware versions.
- Compare against a healthy baseline.
- Focus on delta of error counters.
- Isolate physical vs software causes.
- Reproduce in lab when possible.
- Provide complete snapshots if escalating to vendor support.
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