HP XC System Software Administration Guide Version 3.0

Configuring Nodes in SLURM
You can change the configuration of a set of nodes by editing the slurm.conf file. SLURM enables you
to describe various node characteristics on your system. SLURM uses this description to enable your users
to select an optimal set of nodes for their jobs.
Node Characteristics
The following characteristics are useful on an HP XC system:
Feature Alphanumeric text with meaning in the local environment. This text is a comma-separated
list of features for the specified nodes.
RealMemory The amount of real memory (in megabytes) on the node.
If SLURM finds that the node has less real memory than the value specified, the node's state
is set to DOWN to avoid disrupting jobs that require that minimum.
Procs The number of processors on the node.
If SLURM finds that the node has fewer processors than the value specified, the node's state
is set to DOWN to avoid disrupting jobs that require that minimum.
State The initial state of the node (IDLE or DOWN).
TmpDisk The minimum temporary disk space (in megabytes) available on node.
If SLURM finds that the node has less disk space than the value specified, the node's state
is set to DOWN to avoid disrupting jobs that require that minimum.
Weight The scheduling priority of the node.
Nodes of lower priority are scheduled before nodes of higher priority, all else being equal.
To change the configuration of a set of nodes, first locate the line in the slurm.conf file that starts with
the following text to specify the configuration:
NodeName=
Multiple node sets are allowed on the HP XC system; the initial configuration specifies a single node set.
Consider a system that has 512 nodes, and all those nodes are in the same partition. SLURM partitions are
discussed in “Configuring SLURM Partitions”. The system's slurm.conf file contains the following line:
NodeName=n[1-512] Procs=2 # Set by the SLURM configuration process
This might be reset as follows:
NodeName=DEFAULT Procs=2 TmpDisk=1024 RealMemory=4000
NodeName=n[1-15] RealMemory=1000 Weight=8
NodeName=n[16-127,129] RealMemory=2000 Weight=16
NodeName=n[128,130-512] Feature="noswap" Procs=4 Weight=50
This reset accomplishes the following after SLURM reconfiguration:
• The assignments NodeName=DEFAULT Procs=2 TmpDisk=1024 specify that, by default, all nodes
have two processors and that 1 GB (1,024 MB) of temporary disk space is available on each node,
unless otherwise specified.
• Nodes 1–15 are allocated before any of the others because their Weight is the lowest.
Nodes 128 and 130–512 are allocated last, unless a user requests large memory, the locally defined
noswap feature, or nodes with four processors.
If you make any changes, be sure to run the scontrol reconfigure command to update SLURM with
these new settings.
Configuring SLURM Partitions
Nodes are grouped together in partitions. A node can belong to only one partition.
A SLURM job cannot be scheduled to run across partitions.
Only the superuser (root) and the SLURM system administrator (SlurmUser) are allowed to allocate resources
for any other user.
104 Managing SLURM