| Check | What this checks | Target | Where | Verdict | Measured | Impact and what to do | $/day at risk |
|---|
| Scale-up bandwidth: all-reduce inside one server | Scale-up: how fast the GPUs inside one server combine their results over their own links (NVLink or xGMI). Every multi-GPU step on a server waits on this. | ≥ 560 GB/s reference: 560 GB/s intra-node all-reduce bus bandwidth: no published 8x B300 nccl-tests figure was found, so this is 80% of our own capture (700.5 GB/s on one Nebius node, 2026-09-09) | 1 node | meets | 701 GB/s over 8 GPUs against a floor of 560 | Met. Nothing to do. | none at risk |
| All-reduce returns correct values | Whether the GPUs combined those results correctly. A wrong value here means training would silently go wrong. | 0 incorrect reduction results nccl-tests checks every result | 1 node | meets | nccl-tests verified every reduction result | Met. Nothing to do. | none at risk |
| Uncorrectable memory errors on lifetime record | Uncorrectable memory errors from before this boot, and whether the GPU has repaired the damaged rows since. | row-remapper: remapped and clean is at spec; pending or failed is not NVIDIA row-remapping documentation | 89.124.38.244/gpu5 | meets | 4 lifetime, 1 row remapped, none since boot, no repair pending — normal operation per the driver | A history worth watching, not a fault today | none at risk |
| GPUs fit for work | The share of GPUs that passed every check, against the share the contract promises. | ≥ 97% of GPUs with no failed check reference: 0.97 of GPUs with no failed check | fleet | meets | 8 of 8 (100.0%) with no failed check; target 97% | Met. Nothing to do. | none at risk |
| Network links at contracted rate | The speed each network port negotiated with the switch, against the speed the card can run at or the contract promises. | ≥ 400,000 Mb/s reference: 400 Gb/s: the port rate the B300 node's ConnectX-8 ports reported | 1 ports | meets | all at or above 400,000 Mb/s | Met. Nothing to do. | none at risk |
| PCIe links at full width | How many PCIe lanes connect each GPU to its host. Fewer than the card supports means data moves between CPU and GPU more slowly than it should. | the card's own maximum link width the card's own reported limit | 8 GPUs | meets | all at rated width | Met. Nothing to do. | none at risk |
| Communication exposed on the reference step | What share of that reference step was spent waiting for GPUs to exchange gradients rather than computing, with no overlap: a worst case. | ≤ 25% of the step reference: 0.25 of the un-overlapped reference step: our capture showed 14.5% on 8 GPUs over NVLink; a degraded link roughly doubles it. | 1 node | meets | 14.5% against a ceiling of 25% | Met. Nothing to do. | none at risk |
| Memory bandwidth on the reference step | How fast each GPU can move data through its own memory, against the datasheet figure. Token generation in inference is limited by this, not by raw compute. | ≥ 70% of datasheet memory bandwidth reference: 0.70 of the 8 TB/s datasheet: our capture reached 75-79% with a device-to-device copy; the copy method itself costs 10-15%. | 8 GPUs | meets | 74.6%-78.5% against a floor of 70% | Met. Nothing to do. | none at risk |
| GPU temperatures within limit | GPU temperature against the limit at which the card starts holding its clocks back. | ≤ 85 °C reference: 85 C is an illustrative warning level, not this SKU's manufacturer limit: the B300 on driver 580 does not report its thermal thresholds through nvidia-smi -q, so the vendor-limit comparison is inconclusive and this value is carried over from A100/H100 | 8 GPUs | meets | all at or below 85 C | Met. Nothing to do. | none at risk |
| No hardware-fault messages in the accessible kernel log | Whether the readable part of the kernel log holds any message that public vendor or kernel documentation classes as a hardware fault: uncorrectable PCIe or memory errors, a device dropping off the bus, a GPU reset. Benign and application-level messages are counted but never fail this. The log covers whatever the ring buffer still held at read time. | 0 fault-class messages public kernel and vendor documentation, per signature | 1 node | could not judge | the kernel log could not be read: dmesg is restricted to root on this image and the tool never escalates privileges | → Run with a user that can read dmesg, or grant read access to /dev/kmsg | — |
| Scale-out bandwidth: RDMA write between servers (host memory) | Scale-out: how fast one server's network card can write straight into another server's memory over RDMA (host memory in this test; GPUDirect is not exercised), the east-west path every multi-server job depends on, against the port's speed. | ≥ 80% of the port rate reference: 0.8 of port rate: perftest reaches 90%+ of line rate on a correctly configured path (active MTU 4096); 80% leaves margin. | fleet | could not judge | the RDMA probe is pairwise, one node writing into another; only one node was measured, so there was no pair to test | → Include a second node on the same fabric in the next run | — |
| Reference-step utilisation (MFU) | How much of each GPU's rated compute a fixed reference training step actually achieved (model FLOP utilisation). A GPU that is throttled or misconfigured scores low. This is our step, not your workload. | no target set add mfu_min; the peak itself is the vendor datasheet | 8 GPUs | could not judge | 1290-1363 TFLOP/s achieved; no rated peak on file for this SKU, so MFU cannot be computed | — | — |