The Moment of Verification: Checking a Deployed Instance After an OOM Crisis

Introduction

In the high-stakes world of GPU proving for Filecoin, where every instance costs money and every failed benchmark wastes both time and compute resources, a single SSH connection can feel like a lifeline. Message 1188 of this opencode session captures exactly such a moment: the assistant, having just deployed a series of tactical fixes to combat Out of Memory (OOM) crashes and benchmark timeouts, pauses to check whether the newly created instances are actually running correctly. The message is deceptively brief—a single bash command and its output—but it represents the culmination of hours of debugging, the validation of a hardware-aware configuration system, and a critical checkpoint in a broader strategic shift from guesswork to data-driven deployment.

The Full Message

The assistant writes:

Czechia direct SSH works! Belgium might still be pulling the image. Let me check the manager and Czechia:

>

``bash ssh -o StrictHostKeyChecking=no -o UserHostsFile=/dev/null -p 41821 root@77.48.24.153 'grep -E "entrypoint|Detected|concurrency|partition" /var/log/entrypoint.log 2>/dev/null | head -10; echo "---"; du -sh /var/tmp/filecoin-proof-parameters/ 2>/dev/null; echo "---"; tail -3 /var/log/entrypoint.log 2>/dev/null' 2>/dev/null ``

>

`` [entrypoint] 03:22:18 Starting portavailc tunnel to [REDACTED] ... [entrypoint] 03:22:18 portavailc started (PID=357, attempt=1) [entrypoint] 03:22:18 Tunnel ready (management service reachable) [entrypoint] 03:22:18 Detected 2 GPU(s), 251GB RAM [entrypoint] 03:22:18 RAM=251GB (<400GB), using partition-workers=10 [entrypoint] 03:22:18 Benchmark concurrency=2 (available=151GB, per_proof~60GB, gpu_cap=6) [entrypoint] 03:22:18 Registered: uuid=[REDACTED] runner_id=[REDACTED] ``

At first glance, this is a routine status check. But every line of the output tells a story about the engineering challenges that preceded it.

Why This Message Was Written: The Context of Crisis

To understand why the assistant is running this particular SSH command at this particular moment, we must look back at the cascade of failures that defined the preceding hours. The segment opened with a critical problem: low-RAM GPU instances were being killed during the benchmark warmup phase. The BC Canada instance (125GB RAM) was the first casualty, dying during PCE (Pre-Compiled Constraint Evaluator) extraction when the daemon spawned too many partition workers simultaneously, exceeding the available memory. The Norway instance (500GB RAM, 1x RTX 4090) survived but produced only 41.32 proofs per hour—below the 50 proofs/hour minimum—triggering a lifecycle bug where the manager failed to destroy underperforming instances.

Two major code fixes had been implemented and deployed. First, benchmark.sh was refactored to detect the absence of a PCE cache and start the daemon with partition_workers=2 for the warmup proof, preventing the memory spike of simultaneous partition synthesis. After the PCE file was generated, the daemon was restarted with the full partition count for the actual benchmark. Second, entrypoint.sh was rewritten to dynamically scale benchmark concurrency based on available RAM and GPU count, replacing a hardcoded concurrency=5 with a formula that reserves 100GB overhead and estimates 6GB per partition worker per proof.

But the fixes had only been partially successful. The Belgium instance (2x A40, 2TB RAM) was killed by the manager's 20-minute benchmark timeout—the warmup and SRS preload consumed too much of the window. The Czechia instance (2x RTX 3090, 251GB RAM) suffered a gRPC transport error on its first batch proof, likely because the GPU kernels needed compilation after the daemon restart, pushing the first proof beyond the client's timeout.

The assistant had responded with three tactical fixes: increasing the benchmark timeout from 20 to 45 minutes, adding a "post-restart warmup" proof to benchmark.sh to warm GPU kernels before the timed batch, and refining the partition worker logic to use pw=8 for ~256GB machines. A new Docker image had been built and pushed. A new Belgium instance (32715193) and a new Czechia instance (32715618) had been created.

Message 1188 is the moment the assistant checks whether these new instances are actually working.## The Reasoning Behind the SSH Command

The assistant's decision to SSH into the Czechia instance (77.48.24.153:41821) rather than the Belgium instance reveals a careful prioritization. Belgium had been unreachable via SSH in the preceding messages ([msg 1183], [msg 1184]), with permission denied errors suggesting either a key configuration issue or that the instance was still pulling the Docker image. Czechia, on the other hand, had just been confirmed reachable via direct SSH port 41821 in [msg 1187]. The assistant's comment—"Czechia direct SSH works! Belgium might still be pulling the image"—shows an understanding of the typical vast.ai instance lifecycle: after creation, the instance must download the Docker image, which can take several minutes for a multi-gigabyte image like curio-cuzk:latest.

The choice to grep for specific keywords (entrypoint|Detected|concurrency|partition) is also deliberate. These are the log lines that confirm the dynamic hardware-aware configuration system is working correctly. The assistant isn't checking for general health—it's specifically verifying that the entrypoint script detected the hardware correctly and applied the right parameters. This is a targeted validation of the code changes made in the previous hour.

What the Output Reveals: A Successful Deployment

The output from the Czechia instance is remarkably clean and informative. Each line tells us something important:

[entrypoint] 03:22:18 Starting portavailc tunnel to [REDACTED] ... — The portavailc tunnel, which provides a reverse tunnel for the management service to reach the instance, started successfully. This is the first critical step: without this tunnel, the vast-manager cannot communicate with the instance, and the instance cannot register itself.

[entrypoint] 03:22:18 portavailc started (PID=357, attempt=1) — The tunnel started on the first attempt. This is a positive sign; previous instances had sometimes required multiple attempts due to network issues or port conflicts.

[entrypoint] 03:22:18 Tunnel ready (management service reachable) — The tunnel is confirmed working. The instance can now communicate with the management service at 45.33.141.226:22222.

[entrypoint] 03:22:18 Detected 2 GPU(s), 251GB RAM — The hardware detection is working correctly. This is a 2x RTX 3090 instance with 251GB of RAM, matching the expected configuration.

[entrypoint] 03:22:18 RAM=251GB (<400GB), using partition-workers=10 — This is the critical line. The dynamic partition worker logic has kicked in. The threshold is 400GB: machines with less than 400GB RAM get partition_workers=10, while machines with more get partition_workers=16. This is the fix for the OOM issue—preventing the daemon from spawning too many partition workers on memory-constrained machines.

[entrypoint] 03:22:18 Benchmark concurrency=2 (available=151GB, per_proof~60GB, gpu_cap=6) — The concurrency formula is also working. With 251GB total RAM, the entrypoint reserves 100GB overhead, leaving 151GB available. At an estimated 60GB per proof (for 2x RTX 3090 with partition_workers=10), this yields a theoretical concurrency of 2.5, which is floored to 2. The gpu_cap=6 is a separate limit based on GPU count (2 GPUs × 3 concurrent proofs per GPU, a heuristic from earlier testing).

[entrypoint] 03:22:18 Registered: uuid=[REDACTED] runner_id=[REDACTED] — The instance has successfully registered with the vast-manager. This means the management service knows about it and will monitor its progress.

Assumptions Made by the Assistant

Several assumptions underpin this message. First, the assistant assumes that the SSH connection via the direct port (41821) will work reliably for subsequent checks. This is a reasonable assumption given the successful connection in [msg 1187], but it's worth noting that direct SSH to vast.ai instances can be flaky—ports can be blocked by firewalls, instances can be restarted, and IP addresses can change.

Second, the assistant assumes that the log output is complete and accurate. The grep command filters for specific keywords, which means it could miss important error messages that don't contain those keywords. For example, if the daemon crashed after registration but before starting the benchmark, the grep wouldn't catch it. The assistant partially mitigates this by also running tail -3 /var/log/entrypoint.log, but this only shows the last three lines.

Third, the assistant assumes that the Belgium instance is still pulling the image and will eventually come online. This is an optimistic assumption—Belgium had already failed once (benchmark timeout) and was recreated with the same image but with the updated manager timeout. The assistant doesn't verify that Belgium's SSH key issue is resolved or that the instance is making progress.

Fourth, the assistant assumes that the dynamic configuration values (partition_workers=10, concurrency=2) are correct for this hardware. This is based on the heuristic developed during the OOM debugging, but it hasn't been empirically validated for the 2x RTX 3090 + 251GB RAM combination. The earlier Czechia instance (32714145) had failed with a gRPC transport error, and while the "post-restart warmup" fix was added to address this, the assistant hasn't confirmed that the fix works.

Potential Mistakes and Incorrect Assumptions

The most significant potential mistake is the assumption that the gRPC transport error that killed the previous Czechia instance was caused by cold GPU kernels rather than a deeper issue. The "post-restart warmup" proof added to benchmark.sh runs a single proof after the daemon restart with full partition workers, with retry logic if it fails. But if the gRPC timeout is fundamental—say, the proof genuinely takes longer than the client's default timeout even with warm kernels—then the warmup proof itself might fail, and the retry logic would just burn more time.

Another subtle issue: the assistant checks the entrypoint log but not the daemon log or the benchmark log. The entrypoint log shows the configuration decisions, but it doesn't show whether the daemon actually started successfully or whether the benchmark is progressing. The daemon could crash during initialization (e.g., due to CUDA driver issues or insufficient GPU memory), and the assistant wouldn't know until the next monitoring cycle.

The assistant also doesn't check the vast-manager's perspective. The instance is "registered," but the manager might not have started monitoring it yet, or the monitor might have a stale view. In [msg 1169], the manager showed the previous Czechia instance (32714145) as "killed" with bench_rate 0, but the new instance (32715618) wasn't listed yet. This could mean the manager hasn't processed the registration, or the dashboard API has a caching delay.

Input Knowledge Required

To fully understand this message, one needs knowledge of several domains:

  1. The vast.ai ecosystem: How instances are created, how SSH works (direct vs. proxy), the instance lifecycle (pulling image → starting → running), and the concept of "direct ports" for bypassing SSH proxies.
  2. The cuzk proving engine: What PCE (Pre-Compiled Constraint Evaluator) is, why partition workers matter for memory usage, and how the proving pipeline works (synthesis → GPU proving).
  3. The dynamic configuration system: The RAM thresholds (400GB for partition_workers, 100GB overhead for concurrency calculation), the per-proof memory estimation (6GB per partition worker), and the GPU concurrency cap.
  4. The portavailc tunnel: How the management service communicates with instances, and why a reverse tunnel is needed for instances behind NAT or firewalls.
  5. The previous failures: The OOM crash on BC Canada, the benchmark timeout on Belgium, the gRPC transport error on Czechia, and the specific fixes applied to address each.

Output Knowledge Created

This message creates several pieces of actionable knowledge:

  1. Confirmation that the dynamic configuration system works: The Czechia instance correctly detected 2 GPUs and 251GB RAM, and applied the appropriate partition_workers (10) and concurrency (2) values.
  2. Confirmation that the registration pipeline works: The instance successfully started the portavailc tunnel and registered with the vast-manager, meaning the management service can monitor and control it.
  3. A baseline for comparison: The assistant now has a reference point for what a healthy startup looks like. If Belgium later shows different configuration values (e.g., partition_workers=16 due to its 2TB RAM), that would confirm the hardware-aware logic is working across different machine types.
  4. A checkpoint for debugging: If the Czechia instance later fails, the assistant can look back at this log output to confirm that the configuration was applied correctly, narrowing the search for the root cause.

The Thinking Process Visible in the Message

The assistant's reasoning is visible in the structure of the SSH command. The grep pattern "entrypoint|Detected|concurrency|partition" is not arbitrary—it specifically targets the lines that validate the OOM fix and the dynamic configuration. The assistant is thinking: "I need to confirm that the entrypoint script ran, detected the hardware, and applied the correct partition_workers and concurrency values. If these are wrong, the instance will either OOM (too many partition workers) or underperform (too few)."

The inclusion of du -sh /var/tmp/filecoin-proof-parameters/ in the command (though its output isn't shown in the message) reveals another concern: the assistant wants to verify that the parameter files (SRS files) have been downloaded. These files are several gigabytes each and are essential for proving. If they're missing or incomplete, the benchmark will fail. The fact that this output isn't shown in the message suggests the command may have timed out or the directory was still being populated.

The assistant's comment "Belgium might still be pulling the image" shows an understanding of the asynchronous nature of vast.ai instance creation. The create command returns immediately, but the instance takes time to become ready. Rather than polling aggressively, the assistant prioritizes checking the instance that is already reachable (Czechia) and will check Belgium later.

Conclusion

Message 1188 is a quiet moment of verification in a storm of debugging. It doesn't contain dramatic revelations or complex code changes. But it represents something essential to the engineering process: the disciplined check that a deployed fix is actually working as intended. The assistant doesn't assume success—it reaches out, reads the logs, and confirms that the dynamic configuration system is producing the right values for the hardware at hand.

The output is clean and reassuring. The Czechia instance has started correctly, detected its hardware, applied the appropriate configuration, and registered with the management service. The OOM fix is holding. The dynamic configuration is working. But the assistant knows that the real test is yet to come: the benchmark itself, which will take 30-45 minutes to complete. This message is the first checkpoint, not the last.

In the broader narrative of this segment, message 1188 marks the transition from reactive debugging to proactive monitoring. The assistant has moved from fixing crashes to verifying configurations, and from there will move to analyzing benchmark results and refining the system further. It's a small but necessary step on the path from chaos to control.