SLURM

SLURM

Standalone install? If this session was not initialized by the TAO skill bank plugin, run the tao-setup skill first (host preflight, credentials, cross-skill discovery).

Remote GPU compute platform for clusters managed by SLURM. Jobs are submitted from the launch host to a login node over SSH, staged on a shared filesystem, submitted with sbatch, and executed with srun container support.

When to use

Use SLURM when the user has access to a managed GPU cluster, shared Lustre storage, and scheduler-owned GPU allocation. Do not use SLURM for local files that exist only on the agent machine; data and outputs must be reachable from the cluster.

Preflight + SSH

Confirm SLURM_USER and SLURM_HOSTNAME are exported and passwordless SSH to a login host works (ssh -o BatchMode=yes). The launch host needs ssh, not local sbatch, srun, Enroot, or a Lustre mount. Preflight those scheduler, Pyxis, Enroot, and shared-storage dependencies on the selected remote login/​compute frame. Model-specific inspectors may be streamed from the installed skill over SSH stdin; do not stage an ad-hoc source patch or treat the launch host as the SLURM frame. For private nvcr.io images, install ~/​.config/​enroot/​.credentials on the cluster once per (cluster, user): Pyxis/​Enroot does not read NGC_KEY from the job env, and without persistent credentials, auth-gated pulls fail with "Could not process JSON input" at job startup. Install it via the printf | ssh heredoc so the NGC_KEY value never lands in shell history, intermediate files, or chat output; never cat/echo the value.

If a preflight check fails, the agent prompts the user to authorize the install/​fix via Bash. Pip-installable Python requirements are the exception: install them automatically, then rerun preflight.

See references/​slurm-ssh-credentials.md for the full preflight script, the enroot-credentials heredoc, prerequisite key setup (keypair, ssh-copy-id, known_hosts, container key mounts, 2FA handling), and the SSH failure remediation prompt.

Execution — the four verbs

tao-run-on-slurm is a platform consumer: it runs a spec-bundle over ssh + sbatch/​squeue/​sacct/​scancel, mutating only the job-record. Storage is tier A (Lustre) — the dataset is staged to a shared path before submit and read through Pyxis; never fetch S3 inside the allocation (the scheduler-idle timeout kills GPU-idle jobs and bills the wasted time). $BANK = ${TAO_SKILL_BANK_PATH}; $LOGIN = a resolved SLURM_HOSTNAME.

submit

1. Reuse what's already staged — never redo (tier A):
   • Image: @@IMAGE@@ is a Lustre .sqsh — reuse an existing one if present (ssh $LOGIN ls <sqsh>); only if missing, convert once with enroot import (cached by name — see references/​slurm-container-execution.md).
   • Dataset: confirm it is already on Lustre (ssh $LOGIN test -e …) and reference those paths; tao-data-io stages only a small auxiliary input that is not there yet — never re-stage existing data, and never the training set inside the allocation. Then author the spec at <job_dir>/​specs/​spec.yaml on Lustre with those paths.
2. Credentials → sidecar (never inline): if the run needs session creds (e.g. HF_TOKEN), write them to a mode-600 sidecar on Lustre and let the template shred it on exit; NGC image pulls use the one-time ~/​.config/​enroot/​.credentials (see references/​slurm-ssh-credentials.md), not the job env:

   set -a; source /​path/​to/​.env; set +a   # omit if already exported
   printf 'export HF_TOKEN=%s\n' "$HF_TOKEN" | ssh $LOGIN "umask 077; cat > <job_dir>/​job_$JOB_ID.env"
   

3. Open the record — mints the id, binds results_dir on Lustre, before launch:

   JOB_ID=$("$BANK/​scripts/​tao_job_record.py" open --platform slurm --image "$IMAGE" \
     --network-arch "$ARCH" --action "$ACTION" --storage-tier A --results-root "$SLURM_BASE_RESULTS_DIR")
   

4. Consume the optional model lifecycle. If the validated spec-bundle has execution, preserve its order and semantics while mapping distributed intent to native SLURM/​Pyxis. Stage only its checksum-closed supporting_files. The full generic lifecycle and staging contract is in references/​slurm-container-execution.md.
5. Render templates/​slurm/​singlenode.sbatch.tmpl — substitute every @@<NAME>@@ (JOB_NAME=$JOB_ID, NUM_GPUS, CPUS_PER_TASK, TIME, LOG_DIR, IMAGE, CONTAINER_MOUNTS=<RUNTIME_SUPPLIED_MOUNTS>, COMMAND=<bundle command reading the shared-storage spec>, SBATCH_EXTRA= account/​partition lines, ENV_FILE= the sidecar path or empty, EXTRA_ENV= any cluster NCCL knobs) → <job_dir>/​sbatch/​job_$JOB_ID.sbatch. Lint + syntax-check before submit: redact_secrets.py lint <sbatch> must pass and bash -n <sbatch> must succeed.
6. Submit + record RUNNING:

   SLURM_ID=$(ssh $LOGIN "sbatch --parsable <job_dir>/​sbatch/​job_$JOB_ID.sbatch")
   "$BANK/​scripts/​tao_job_record.py" mark "$JOB_ID" --state RUNNING --backend-ref "$SLURM_ID"
   

A submit that skipped the gate or the open has no id — so it cannot launch.

status

# sacct ANNOTATES states ("CANCELLED by 12345") and truncates them to the
# default column width, so a cancelled job reads back as "CANCELLED+" and
# matches nothing in the table below — reporting UNKNOWN instead of CANCELED.
# Widen the column, take the first word, drop the truncation marker.
st=$(ssh $LOGIN "sacct -j $SLURM_ID -X -n -o State%30" | awk '{print $1}' | tr -d '+')
# (use squeue while the job is still PENDING; sacct lags briefly after submit)

Native sub-state rides in the transition message. Poll at the chosen interval; long queue waits are normal — do not stop on elapsed time.

logs

ssh $LOGIN "tail -n ${N:-200} <log_dir>/​$JOB_ID-$SLURM_ID/​main.out"   # SLURM auto-creates the %x-%j subdir

cancel

ssh $LOGIN "scancel $SLURM_ID"
"$BANK/​scripts/​tao_job_record.py" mark "$JOB_ID" --state CANCELED --source agent

Treat an already-terminated SLURM job as a successful cancel.

Multi-node (nodes > 1)

Same four verbs, with three additions at submit:

1. Render templates/​slurm/​multinode.sbatch.tmpl instead of the single-node one — it's a strict superset (adds --nodes / --wait-all-nodes + the rendezvous block). WORLD_SIZE is the node count (TAO's misnomer); never change it to a global-rank count.
2. NCCL probe first — before the real job, run a cheap 2-node all-reduce (scripts/​nccl_allreduce_probe.py under the container's torchrun) with a ~120s timeout. Before invoking torchrun, preserve the TAO rendezvous values as TAO_NODE_COUNT=$WORLD_SIZE, TAO_GPUS_PER_NODE=$NUM_GPU_PER_NODE, and TAO_NODE_RANK=$SLURM_PROCID; torchrun overwrites its standard WORLD_SIZE with the global process count. NCCL_PROBE_OK → proceed. Timed out (the collective hung) → set the cluster's NCCL knob in EXTRA_ENV and re-probe — on CS-OCI-ORD that is export NCCL_P2P_DISABLE=1 (the intra-node P2P hang), often with NCCL_SOCKET_IFNAME=eth0 / NCCL_IB_DISABLE=1. Cache the working env per cluster so later jobs skip the probe. Gate on gpus_per_node > 1 too — the P2P hang triggers on a single node with 2+ GPUs.
3. Tier-A Lustre, sidecar creds, record, and lint are unchanged.

Cosmos backend guardrails

Read references/​cosmos-slurm-guardrails.md before rendering a Cosmos command. It defines image staging, planner materialization, Framework and Cosmos-RL launch contracts, worker/​runtime requirements, and exit/​status handling.

Storage

Use shared-filesystem URIs, not local or file:// paths; tao-core rejects local/​file paths for remote backends.

• lustre:///absolute/​path for user-provided datasets on Lustre.
• slurm:// paths may appear in microservices metadata and are converted to Lustre paths before the container starts.

Accept either dataset roots (model skills map them to required files) or direct spec-key paths. After SSH succeeds and before generating scripts, test -e each required dataset path from the login host; if it fails, stop and ask for corrected paths or staged data rather than producing scripts that fail in the first training job. See references/​slurm-ssh-credentials.md for root vs. direct-spec modes, backend details, and the results-dir default.

Container execution

tao-core runs TAO containers through Pyxis/​Enroot:

1. Stage compact JSON files for specs, environment, and cloud metadata under <job_dir>/​specs, <job_dir>/​env, and <job_dir>/​meta.
2. Convert the Docker image to a cached SQSH image before the GPU job, with srun -n1 -p <conversion_partition> enroot import. This is a one-time cost per image, not an optional optimization — see Acquire the image off the GPU allocation below.
3. Write an sbatch script under <job_dir>/​sbatch/​job_<job_id>.sbatch.
4. Submit sbatch --export=ALL <script>.
5. Run the container with srun --container-image=<image> --container-mounts=<RUNTIME_SUPPLIED_MOUNTS>.

Accepted image formats: /​path/​to/​image.sqsh, registry#image:tag, docker://registry#image:tag, and ordinary registry/​image:tag (converted to Pyxis form when needed). SQSH conversion is cached by image name; for :latest images the cached SQSH is reused unless force_reconvert_latest is enabled.

Acquire the image off the GPU allocation

The GPU is yours from the moment the allocation starts, not from when compute begins. Anything the job does before training — pulling a registry image, converting it, fetching a dataset — runs on GPUs that are idle, billed, and visible to the cluster's GPU-idle reaper. A first-time TAO pull plus enroot conversion is minutes of that, which is long enough to be killed and long enough to be expensive.

So the image must already be a local .sqsh when the GPU job starts. Passing a docker:// or registry#image:tag URI straight to srun --container-image= makes Pyxis pull and convert inside the allocation — the exact trap. Convert once on a CPU partition, then point every later job at the resulting file:

# One-time per image, on CPU — costs no GPU time.
ssh $LOGIN "test -e <sqsh>" || \
  ssh $LOGIN "srun --chdir=/​tmp -n1 -c4 --mem=7200M \
    -p <cpu_partition> -t <minutes> \
    bash -c 'set -Eeuo pipefail
      export TMPDIR=/​tmp
      export ENROOT_TEMP_PATH=/​tmp/​enroot-tao-\${SLURM_JOB_ID}
      export SLURM_ENROOT_TEMP_PATH=\${ENROOT_TEMP_PATH}
      mkdir -p \"\${ENROOT_TEMP_PATH}\"
      cd /​tmp
      enroot import -o <sqsh> docker://<registry>#<image>:<tag>'"

# Every GPU job then references the file, never the registry.
srun --container-image=<sqsh> ...

The same rule governs data: stage it to Lustre before submit (tier A) rather than fetching inside the allocation.

CS-OCI-ORD conversion uses cpu_long, 4 CPUs, 7200M memory, no exclusive node, node-local Enroot temp paths, and at least 120 minutes. The execution reference records the evidence and QOSGrpMemLimit recovery contract.

Partial conversions are self-detecting: the SQSH is validated by hsqs magic, so a truncated file is rejected rather than silently used. Conversion runs once and is then cached by image name.

A failed conversion must not fall back to the registry image. The tempting recovery — pass docker://… to srun and let Pyxis handle it — puts the pull back inside the GPU allocation, which is the cost the conversion existed to avoid, and it does so precisely when something is already wrong. Treat a failed or truncated conversion as fatal: fix it on the CPU partition and resubmit.

Diagnostic: if a job is unexpectedly slow to produce output, check what --container-image= actually received. A registry URI there — rather than a .sqsh path — means the pull happened on the GPUs.

Monitoring and cancellation

• Scheduler status comes from the stored SLURM job id via squeue/sacct; TAO terminal status comes from status.json in the shared results folder.
• While chat monitoring is enabled, keep polling at the requested interval for any non-terminal job (PENDING, RUNNING, or otherwise). Do not stop after a fixed elapsed time such as 30 minutes; long queue waits are normal on shared GPU partitions.
• Do not send a final response for a non-terminal SLURM job when chat monitoring is enabled. A final response is a detach action; use it only if the user asked to detach/​stop or the job reached terminal state.
• Logs are read over SSH from <job_dir>/​slurm-logs/<slurm_job_name>-<slurm_job_id>/​main.out and .err.
• Cancel by looking up backend_details.slurm_metadata.slurm_job_id and running scancel <slurm_job_id> over SSH. Treat missing or already terminated jobs as successful cancellation.

Status mapping:

• PENDING -> Pending
• RUNNING or COMPLETING -> Running
• COMPLETED -> check status.json
• FAILED, BOOT_FAIL, DEADLINE, OUT_OF_MEMORY, NODE_FAIL -> retry if logs match retriable infrastructure patterns, otherwise Error
• CANCELLED, PREEMPTED, REVOKED -> Canceled
• TIMEOUT -> Error
• SUSPENDED, STOPPED -> Running (still scheduler-owned and may resume; the native sub-state rides in the transition message — same convention as docker paused)

Required inputs

Ask for these in the SLURM intake; see references/​slurm-ssh-credentials.md for the full credential list, microservices schema keys, and defaults.

• SLURM_USER (required): SSH username for the login node.
• SLURM_HOSTNAME (required): Comma-separated login hostnames for failover.
• SLURM_PARTITION (required): Partition list for GPU submission. Packaged default polar,polar3,polar4,grizzly, treated as 4-hour queues.
• SSH_KEY_PATH (preferred, expected before launch): private key for non-interactive public-key auth. Ask for this first in remediation; prefer it over the SSH_AUTH_SOCK agent-socket fallback.
• SLURM_BASE_RESULTS_DIR (optional): base shared-filesystem path; default a shared-storage root supplied and verified at runtime.
• SLURM_ACCOUNT (usually required by site policy): account for #SBATCH --account.

Do not ask for SLURM_ACCOUNT or SLURM_BASE_RESULTS_DIR in the initial intake unless the user says their site requires an account, wants a custom results root, or the workflow cannot proceed without overriding defaults.

Resource defaults

Defaults from tao-core:

• num_nodes: 1
• num_gpus: 4
• max_num_gpus_per_node: 8
• cpus_per_task: 16
• time_hours: 4
• timeout_hours: 3.8
• max_time_hours: 4
• container_mounts: explicit source-to-target mounts supplied at runtime
• use_requeue: true
• use_sqsh: true

Launchers must use the packaged 4-hour wall and 3.8-hour child-timeout defaults, never 12 hours. If the user supplies a longer SLURM_TIME_HOURS, verify that the selected partition supports it before submitting. For the packaged default partition list polar,polar3,polar4,grizzly, reject requests above 4 hours and ask for a different partition only if the user actually wants a longer wall time.

At or above max_num_gpus_per_node, allocate exclusive nodes and derive their count from total GPUs.

Multi-node and retries

For multi-node jobs (num_nodes > 1), the rendered templates/​slurm/​multinode.sbatch.tmpl sets the sbatch directives and exports the PyTorch-distributed rendezvous env vars: WORLD_SIZE, NUM_GPU_PER_NODE, NODE_RANK, MASTER_ADDR, and MASTER_PORT (29500). TAO entrypoints read WORLD_SIZE + NUM_GPU_PER_NODE and build torchrun internally. Cosmos-RL has special multi-node role handling for controller, policy, and rollout workers. See the ### Multi-node (nodes > 1) submit subsection above for the NCCL-probe gate and per-cluster env caching.

Use Lustre, not S3, for SLURM job inputs. The GPU allocation starts the moment the job is dispatched, so a long s3:// download at the top of the script burns the allocation, can get the job killed for GPU-idle, and is billed either way. Stage training data on the shared filesystem first and reference it as lustre:///.... S3/​HF/​NGC pre-fetch is fine for small auxiliary inputs (checkpoints, configs), not training datasets. K8s/​Brev do not share this scheduler-idle constraint.

On an infrastructure failure (NODE_FAIL, BOOT_FAIL, NCCL transport timeouts, CUDA driver init failures, GPU/​IB link-down, OOM-killer node reaping, Xid errors), classify infra-vs-program from the logs and create a new retry record with --retry-of before re-submitting the staged workload (M6). Plain training failures surface immediately so a broken spec does not consume the retry budget. #SBATCH --requeue is enabled by default via SLURM_USE_REQUEUE=true, so SLURM itself re-queues the job on NODE_FAIL or pre-emption before any agent-level resubmit; workload contracts such as Cosmos may require --no-requeue.

Treat an empty sbatch --parsable response or SSH disconnect as ambiguous: reconcile by exact job name, never submit blindly, and validate inherited node exclusions. The referenced execution guide defines the full decision table. See references/​slurm-container-execution.md for the full multi-node env-var/​sbatch directive detail and table, cluster requirements, the Lustre-not-S3 rule in full, and the failure-mode checklist.

References

• references/​slurm-ssh-credentials.md — preflight script, SSH/​key setup, enroot credentials, full credential list, backend details, storage rules, SSH remediation prompt.
• references/​slurm-container-execution.md — container execution steps, monitoring, status mapping, cancellation, multi-node detail, Lustre-not-S3, retries, failure modes.
• references/​slurm-preflight-storage.md — extended preflight/​storage notes.
• references/​cosmos-slurm-guardrails.md — Cosmos Framework and Cosmos-RL launch and status guardrails.
• references/​detailed-guide.md — navigation map for the split references.