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power_save

README.md

Slurm power saving scripts

The present Slurm power saving scripts have been designed to be called from the Slurm controller slurmctld using the slurm.conf resume and suspend programs discussed below. The programs can also be called directly from the command line. They will call different helper scripts according to the type of power management relevant for different types of nodes.

The power management type for each node set is configured as node features in slurm.conf.

In case you want to use the IPMI based tool power_ipmi, please configure all the IPMI tools discussed below.

General Slurm configurations related to power saving are described in the page https://slurm.schedmd.com/power_save.html.

Prerequisites

  1. Slurm's power saving (prior to version 22.05.6) requires Slurm to be built with JSON support as described in the Wiki page Slurm configuration for cloud nodes. This is described in bug 14925.

  2. In case you want to use the IPMI based tool power_ipmi, you must install the GNU FreeIPMI packages:

    yum install freeipmi freeipmi-devel

    The RPM versions (especially on EL7) are quite old, so it is possible to download the latest Fedora source RPM file and rebuild the set of packages, for example on EL7:

    yum install libgcrypt-devel texinfo
rpmbuild --rebuild freeipmi-1.6.10-1.fc38.src.rpm
yum install rpmbuild/RPMS/x86_64/freeipmi-1.6.10-2.el7.x86_64.rpm rpmbuild/RPMS/x86_64/freeipmi-devel-1.6.10-2.el7.x86_64.rpm

  3. The scripts in the present project require the nodeset command from the ClusterShell package, install it as RPM packages by:

    yum install epel-release
yum install clustershell

Usage

Copy these scripts to /usr/local/bin/:

cp noderesume nodefailresume nodesuspend power_ipmi power_azure power_statistics /usr/local/bin/

Configure script variables

We need to configure the BMC's DNS hostname as well as the IPMI administrator username and password for the ipmipower command. For security reasons the username/password should be kept in a separate file which cannot be read by normal users. The helper script ipmi_setup may be useful for setting up IPMI on every compute node.

Add these lines to the slurm user's .bashrc file (and for other users who need to execute the script) which should export variables for power_ipmi, for example:

export IPMI_USER=root
export IPMI_PASSWORD=<verysecretpassword>
# Define the node BMC DNS name: BMC DNS-name is the node name plus this suffix:
export BMC_SUFFIX="b"

This file will be sourced by the scripts.

In the nodefailresume script configure the sysadmin E-mail address in this line:

slurm_notify=<sysadmin-email>

Test the power_statistics tool

The power_statistics tool uses the ipmi-dcmi command to gather power usage statistics from the node BMCs. Example:

power_statistics  e[001-004]
e001b: Current Power                        : 825 Watts
e002b: Current Power                        : 846 Watts
e003b: Current Power                        : 851 Watts
e004b: Current Power                        : 875 Watts

Test IPMI power scripts

First make sure that the IPMI power scripts are actually working by querying some nodes as user slurm on the slurmctld server:

[slurm@ctld ~]$ power_ipmi -q d004,d005,c190
----------------
d004b,d005b
----------------
 on
----------------
c190b
----------------
 off

Here the nodes' BMC hostnames are being listed.

Adding node features

The nodesuspend and noderesume scripts require the addition of node features in slurm.conf.

We must define some node features power_xxx, for example:

NodeName=node[001-100] Feature=xeon2650v4,opa,xeon24,power_ipmi
NodeName=cloud[001-100] Feature=xeon8272cl,power_azure

The features are used by the nodesuspend and noderesume scripts to identify the power management features associated with each node. The scripts currently handle power_ipmi, power_azure, and power_noaction features, but other features may be added.

Logging of power savings

The power saving script logs actions in files in the Slurm log directory:

/var/log/slurm/power_ipmi.log
/var/log/slurm/power_noaction.log
/var/log/slurm/power_azure.log
/var/log/slurm/nodefailresume.log

The log files must be writable by the slurm user, verify by:

scontrol show config | grep SlurmUser
ls -la /var/log/slurm

slurm.conf configuration

Configure slurm.conf with appropriate resume and suspend parameters:

ResumeProgram=/usr/local/bin/noderesume
ResumeRate=60
ResumeFailProgram=/usr/local/bin/nodefailresume
SuspendProgram=/usr/local/bin/nodesuspend

There are some additional configurations which are used when the cluster contains nodes using power saving (including cloud nodes):

# Exceptions to the node suspend/resume logic (partitions):
SuspendExcParts=xeon8,xeon16,xeon24	# Example
SuspendExcNodes=onprem[001-002]		# Example
SlurmctldParameters=idle_on_node_suspend,cloud_dns
ResumeTimeout=600
SuspendTimeout=120
DebugFlags=Power
TreeWidth=65536		# Configure TreeWidth only when cloud nodes are used

In bug 14270 (resolved in 23.02) there is a workaround for slurm.conf to make cloud nodes visible to sinfo:

PrivateData=cloud

Note some important points:

  • If you set SuspendTime to anything but INFINITE (or -1), power saving shutdown of all idle nodes will commence immediately as soon as you reconfigure Slurm!

  • It is recommended to omit the global parameter and leave it with the default value SuspendTime=INFINITE.
    In stead define it only on any relevant partitions, for example:

    PartitionName=my_partition SuspendTime=3600

  • Nodes that are in multiple partitions which have different SuspendTime values, the power saving may behave unexpectedly.

  • The Slurm control daemon must be restarted to initially enable power saving mode:

    systemctl restart slurmctld

    When changes are made subsequently, it suffices to reconfigure the Slurm controller:

    scontrol reconfig

    Enablement of the power_save module will be shown in slurmctld.log like:

    <timestamp> power_save module, excluded nodes ...

  • Compute nodes that are drained for maintenance purposes will be suspended and later resumed when needed by jobs. This is highly undesirable!

    This issue has been resolved in Slurm 23.02 by bug 15184 which introduces a new slurm.conf parameter SuspendExcStates. This permits to configure node states which you want to be excluded from power saving suspension. Valid states for SuspendExcStates include:

    CLOUD, DOWN, DRAIN, DYNAMIC_FUTURE, DYNAMIC_NORM, FAIL, INVALID_REG, MAINTENANCE, NOT_RESPONDING, PERFCTRS, PLANNED, RESERVED

    We recommend to configure SuspendExcStates=DOWN,DRAIN,FAIL.