Migrating from Slurm

Migrating from Slurm#

Spur is drop-in compatible with Slurm’s command-line interface, REST API, and C FFI. Most Slurm workloads move over unchanged. This page covers what works as-is, where the configuration model differs, and the behavioral differences a Slurm user should know about before switching.

What Works Unchanged#

The following work without modification:

  • Commands — sbatch, srun, salloc, squeue, sinfo, sacct, scancel, scontrol, and sacctmgr (via the symlinks described in Slurm Compatibility).

  • Job script directives — #SBATCH directives in batch scripts are parsed the same way. #PBS directives are also converted on a best-effort basis.

  • Environment variables — Spur sets a SLURM_* twin for every SPUR_* variable it injects into a job, so Slurm-aware software (MPI launchers, training frameworks) sees the SLURM_* names it expects.

  • REST API and C FFI — the REST surface and the FFI library remain Slurm-compatible.

Configuration Differences#

Slurm’s slurm.conf and slurmdbd.conf are replaced by a single TOML file, spur.conf (default location /etc/spur/spur.conf). Key differences:

  • One config file, one set of daemons. There is no slurmdbd and no slurmrestd — accounting and the REST API are served by the controller (spurctld). Accounting storage is configured under [accounting] in spur.conf rather than in a separate slurmdbd.conf.

  • Raft-based state. Controller state is replicated through Raft and persists across restarts, so there is no StateSaveLocation handling to manage separately.

  • Built-in high availability. HA is provided by Raft (openraft) and is always on — even a single controller runs a one-member cluster. There is no separate backup-controller configuration; add controllers to the Raft cluster instead.

See Configuration Reference (spur.conf) for the full spur.conf reference.

Behavioral Differences and Current Limitations#

The commands below accept Slurm syntax, but the following differences apply. Flags noted as “accepted for compatibility” parse without error but have no effect yet.

Area

Difference

Partitions

Defined in spur.conf; there is no runtime scontrol create/update/delete partition. Edit the config and reload the controller to change a partition.

squeue --sort

Accepted for compatibility; result ordering is not yet applied.

sinfo --states

Accepted for compatibility; the state filter is not yet applied (all node states are returned).

sacct --jobs

Accepted for compatibility; the job-id filter is not yet applied server-side.

sacct ReqMem

The ReqMem format field has no value yet and renders empty.

squeue format

The %b (GRES) and %L (time-left) format fields are not yet resolved.

sstat

Per-process Ave* and Max* metrics (for example AveRSS, MaxVMSize) show N/A.

sprio

The FAIRSHARE column is a placeholder and does not yet reflect usage.

scancel arrays

Array-element syntax (123_4) is not yet supported client-side; cancel by plain job id.

scontrol show

Output is always the multi-line Key=Value block; there is no --oneliner.

Accounting and QOS Mapping#

Accounting entities map directly from Slurm:

  • sacctmgr add account, sacctmgr add user, and sacctmgr add qos work as in Slurm, following the same cluster → account → user → association → QOS ordering.

  • The [accounting] require_qos setting is the equivalent of Slurm’s AccountingStorageEnforce=qos.

  • The default_qos setting is the equivalent of Slurm’s fallback QOS.

See Accounting, Accounts, Users, and QOS for the accounting concept guide.

Tip

Before migrating a production workload, test the golden path on a small cluster first: submit a job (sbatch), check the queue (squeue), cancel a job (scancel), and review accounting history (sacct).

See Also#

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