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# InfiniBand Checks

InfiniBand covers InfiniBand network health: port state, error rates, and link integrity.

## RDMA Link Flap (Fatal)

`rdma_linkflap_fatal`

Detects mlx5 RDMA interface link outages that lasted at least min_outage_seconds, parsed from the system journal. Fails CRITICAL once the count of such outages reaches fatal_flap_threshold.

| Property | Value |
|---|---|
| Provenance | <nobr>`nvidia`</nobr> |
| Condition scope | <nobr>`CLUSTER`</nobr> |
| Execution class | <nobr>`PASSIVE`</nobr> |
| Scheduling cadence | <nobr>`CONTINUOUS`</nobr> |
| Maturity | <nobr>`stable`</nobr> |
| Execution contexts | <nobr>`OPERATOR_INFRA`</nobr>, <nobr>`TENANT_GUEST`</nobr> |
| Architectures | <nobr>`GB200`</nobr>, <nobr>`GB300`</nobr> |
| Required signals | <nobr>`outage_durations`</nobr> |

**Thresholds**

| Name | Value | Unit | Category | Description |
|---|---|---|---|---|
| <nobr>`fatal_flap_threshold`</nobr> | 1 | count | <nobr>`DEFAULT`</nobr> | Number of outages at or above min_outage_seconds that fails the check. Override per fleet. |
| <nobr>`min_outage_seconds`</nobr> | 30 | seconds | <nobr>`DEFAULT`</nobr> | Minimum down→up outage length, in seconds, for an RDMA link transition to count as a fatal flap. Override per fleet. |

**Rules**

- **CRITICAL** when `size(outage_durations.filter(d, d >= min_outage_seconds)) >= fatal_flap_threshold`
  - Message: RDMA link outage(s) lasting at least $\{min_outage_seconds\}s reached the fatal-flap threshold of $\{fatal_flap_threshold\}. See flap_events for the affected interfaces.

**Recommended action:** operational state `drain`, then `reset_gpu` → `restart_os` → `service_required`