--- name: "topology.yaml" section: "5" platform: "linux" package: "slurm-llnl" version: "26.05.5.1-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/topology.yaml" --- # topology.yaml(5) Slurm configuration file for the topology plugins ## NAME topology.yaml - Slurm configuration file for the topology plugins ## DESCRIPTION **topology.yaml** is a YAML-formatted configuration file that defines multiple network topologies for optimizing job resource allocation in Slurm. The file must be located in the same directory as **slurm.conf**. Any text following a "#" in this file is treated as a comment through the end of that line. Additional details are available in [**topology.conf**(5)](/topology.conf/5.md) and in the Topology Guide: \ **NOTE**: Slurm will first check for topology.yaml. If this file exists, topology.conf will be ignored. ## PARAMETERS Each topology contains the following attributes: - **topology** Unique name of the topology, will be used to identify it on partition configurations. Must be the first attribute. - - **cluster\_default** The first topology defined with **cluster\_default: true** will be used for partitions without an explicitly specified topology and cluster-wide operations not tied to a partition (e.g., slurmctld-to-slurmd communication). Defaults to **false**. - Each topology must also define exactly one of the following topology types: - **block** This topology will use the **topology/block** plugin. Must contain additional fields, see below. - - **flat** If set to **true**, this topology will use the **topology/flat** plugin, which is the default if no TopologyPlugin or topology.yaml is specified. May also be set to a dictionary of options, see "Flat definitions" below. - - **ring** This topology will use the **topology/ring** plugin. Must contain additional fields, see below. - - **torus3d** This topology will use the **topology/torus3d** plugin. Must contain additional fields, see below. - - **tree** This topology will use the **topology/tree** plugin. Must contain additional fields, see below. - ### Block definitions Each block topology contains the following attributes: - **block\_sizes** List of the planning base block size, alongside any higher-level block sizes that would be enforced. Successive **BlockSizes** must be a power of two larger than the prior values. - - **blocks** List of blocks available in this topology. Each block contains the following attributes: - **block** The name of a block. This name is internal to Slurm and arbitrary. Each block should have a unique name. This field must be specified. - - **nodes** Child nodes of the named block. - - ### Tree definitions Each tree topology contains the following attribute: - **switches** List of switches available in this topology. Each switch contains the following attributes: - **switch** The name of a switch. This name is internal to Slurm and arbitrary. Each switch should have a unique name. This field must be specified and cannot be longer than 64 characters. - - **children** Child switches of the named switch. - - **nodes** Child nodes of the named leaf switch. - - ### Ring definitions Each ring topology contains the following attribute: - **rings** List of rings available in this topology. Each ring contains the following attributes: - **ring** The name of a ring. This name is internal to Slurm and arbitrary. Each ring should have a unique name. This field must be specified. - - **nodes** Ordered list of child nodes in the ring. A maximum of 16 nodes can be specified per ring. - - ### Torus3d definitions Each torus3d topology contains the following attribute: - **toruses** List of 3D torus definitions. Each torus contains the following attributes: - **name** The name of the torus. This name is internal to Slurm and arbitrary. Each torus should have a unique name. This field must be specified. - - **dims** The dimensions of the torus as an object with **x**, **y**, and **z** fields (each a positive integer). The product x\*y\*z defines the total number of coordinate cells in the torus. - - **nodes** Child nodes of the torus. Nodes are mapped to coordinates in x-major order (x varies fastest). Mutually exclusive with **regions**. - - **regions** List of regions within the torus that map subsets of coordinates to nodes. Mutually exclusive with **nodes**. Each region contains the following attributes: - **anchor** Starting coordinate of the region as an object with **x**, **y**, and **z** fields. - - **dims** Size of the region as an object with **x**, **y**, and **z** fields. The region covers coordinates from **anchor** to **anchor** + **dims** - 1. The region must fit within the torus dimensions (no wrap-around). - - **nodes** Nodes to place in the region, mapped in x-major order within the region's coordinate range. - - - **placements** List of allowed placement shapes for this torus. Jobs requesting a number of nodes matching a placement size will be allocated as a contiguous sub-cube that may wrap around torus boundaries. Jobs that don't match any placement size will not receive an allocation. Each placement contains the following attributes: - **dims** Dimensions of the placement shape as an object with **x**, **y**, and **z** fields. The product x\*y\*z defines the placement size (number of nodes). - - **anchor\_seed** Optional starting coordinate offset for the anchor grid as an object with **x**, **y**, and **z** fields. Shifts the entire anchor grid by the given offset. Defaults to {0, 0, 0}. - - **anchor\_spacing** Optional spacing between placement anchors as an object with **x**, **y**, and **z** fields. Controls how anchor positions are generated across the torus. Defaults to the placement **dims** if not specified. - - ### Flat definitions Each flat topology may contain the following attribute: - **alpha\_step\_rank** If set to **true**, sort the job's allocated nodes alphabetically by name when picking step nodes and laying out tasks. By default the order follows the internal node table index, which for dynamically registered nodes reflects registration order rather than name order. - ## EXAMPLE ``` --- - topology: topo1 cluster_default: true tree: switches: - switch: sw_root children: s[1-2] - switch: s1 nodes: node[01-02] - switch: s2 nodes: node[03-04] - topology: topo2 cluster_default: false block: block_sizes: - 4 - 16 blocks: - block: b1 nodes: node[01-04] - block: b2 nodes: node[05-08] - block: b3 nodes: node[09-12] - block: b4 nodes: node[13-16] - topology: topo3 cluster_default: false flat: true - topology: topo3a cluster_default: false flat: alpha_step_rank: true - topology: topo4 cluster_default: false ring: rings: - ring: ring0 nodes: node[01-08] - ring: ring1 nodes: node[09-16] - topology: topo5 cluster_default: false torus3d: toruses: - name: pod1 dims: x: 4 y: 4 z: 2 nodes: node[01-32] placements: - dims: x: 2 y: 2 z: 1 - dims: x: 2 y: 2 z: 2 - dims: x: 4 y: 4 z: 2 ``` ## COPYING Copyright (C) 2025 SchedMD LLC. This file is part of Slurm, a resource management program. For details, see \. Slurm is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. Slurm is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. ## SEE ALSO [**slurm.conf**(5)](/slurm.conf/5.md), [**topology.conf**(5)](/topology.conf/5.md)