# Quick Start Administrator Guide

## Overview

Please see the Quick Start User Guide for a general overview.

Also see Platforms for a list of supported computer platforms.

This document also includes a section specifically describing how to perform upgrades.

## Super Quick Start

1. Make sure the clocks, users and groups (UIDs and GIDs) are synchronized across the cluster.
2. Install MUNGE for authentication. Make sure that all nodes in your cluster have the same munge.key. Make sure the MUNGE daemon, munged, is started before you start the Slurm daemons.
3. bunzip2 the distributed tar-ball and untar the files:
   tar --bzip -x -f slurm*tar.bz2
4. cd to the directory containing the Slurm source and type ./configure with appropriate options, typically --prefix= and --sysconfdir=
5. Type make to compile Slurm.
6. Type make install to install the programs, documentation, libraries, header files, etc.
7. Build a configuration file using your favorite web browser and the Slurm Configuration Tool.
   NOTE: The SlurmUser must exist prior to starting Slurm and must exist on all nodes of the cluster.
   NOTE: The parent directories for Slurm's log files, process ID files, state save directories, etc. are not created by Slurm. They must be created and made writable by SlurmUser as needed prior to starting Slurm daemons.
   NOTE: If any parent directories are created during the installation process (for the executable files, libraries, etc.), those directories will have access rights equal to read/write/execute for everyone minus the umask value (e.g. umask=0022 generates directories with permissions of "drwxr-r-x" and mask=0000 generates directories with permissions of "drwxrwrwx" which is a security problem).
8. Type ldconfig -n <library_location> so that the Slurm libraries can be found by applications that intend to use Slurm APIs directly.
9. Install the configuration file in <sysconfdir>/slurm.conf.
   NOTE: You will need to install this configuration file on all nodes of the cluster.
10. systemd (optional): enable the appropriate services on each system:
    - Controller: `systemctl enable slurmctld`
    - Database: `systemctl enable slurmdbd`
    - Compute Nodes: `systemctl enable slurmd`
11. Start the slurmctld and slurmd daemons.

NOTE: Items 3 through 8 can be replaced with

1. `rpmbuild -ta slurm*.tar.bz2`
2. `rpm --install <the rpm files>`

FreeBSD administrators should see the FreeBSD section below.

## Building and Installing Slurm

Instructions to build and install Slurm manually are shown below. See the README and INSTALL files in the source distribution for more details.

1. Unpack the distributed tarball:
   `tar -xaf slurm*tar.bz2`
2. `cd` to the directory containing the Slurm source and type `./configure` with appropriate options (see below).
3. Type `make install` to compile and install the programs, documentation, libraries, header files, etc.
4. Type `ldconfig -n <library_location>` so that the Slurm libraries can be found by applications that intend to use Slurm APIs directly. The library location will be a subdirectory of PREFIX (described below) and depend upon the system type and configuration, typically lib or lib64. For example, if PREFIX is "/usr" and the subdirectory is "lib64" then you would find that a file named "/usr/lib64/libslurm.so" was installed and the command `ldconfig -n /usr/lib64` should be executed.

A full list of `configure` options will be returned by the command `configure --help`. The most commonly used arguments to the `configure` command include:

`--enable-debug`
Enable additional debugging logic within Slurm.

`--prefix=PREFIX`
Install architecture-independent files in PREFIX; default value is /usr/local.

`--sysconfdir=DIR`
Specify location of Slurm configuration file. The default value is PREFIX/etc

If required libraries or header files are in non-standard locations, set `CFLAGS` and `LDFLAGS` environment variables accordingly. Optional Slurm plugins will be built automatically when the `configure` script detects that the required build requirements are present. Build dependencies for various plugins and commands are denoted below:

- cgroup Task Affinity The task/cgroup plugin will be built with task affinity support if the hwloc development library is present.
- HDF5 Job Profiling The acct_gather_profile/hdf5 job profiling plugin will be built if the hdf5 development library is present.
- HTML Man Pages HTML versions of the man pages will be generated if the man2html command is present.
- IPMI Energy Consumption The acct_gather_energy/ipmi accouting plugin will be built if the freeipmi development library is present.
- InfiniBand Accounting The acct_gather_interconnect/ofed InfiniBand accounting plugin will be built if the libibmad and libibumad development libraries are present.
- Lua Support The lua API will be available in various plugins if the lua development library is present.
- MUNGE The auth/munge plugin will be built if the MUNGE authentication development library is installed. MUNGE is used as the default authentication mechanism.
- MySQL MySQL support for accounting will be built if the mysql development library (preferably version 5.5 or later), or if the MariaDB development library is present.
- PAM Support PAM support will be added if the PAM development library is installed.
- NUMA Affinity NUMA support in the task/affinity plugin will be available if the numa development library is installed.
- Readline Support Readline support in scontrol and sacctmgr's interactive modes will be available if the readline development library is present.
- RRD External Sensor Data Collection The ext_sensors/rrd plugin will be built if the rrdtool development library is present.
- sview The sview command will be built only if gtk+-2.0 is installed.

Please see the Download page for references to required software to build these plugins.

To build RPMs directly, copy the distributed tarball into a directory and execute (substituting the appropriate Slurm version number):
`rpmbuild -ta slurm-20.02.1.tar.bz2`

The rpm files will be installed under the `$(HOME)/rpmbuild` directory of the user building them.

You can control some aspects of the RPM built with a .rpmmacros file in your home directory. Special macro definitions will likely only be required if files are installed in unconventional locations. Some macro definitions that may be used in building Slurm include:

_enable_debug
  Specify if debugging logic within Slurm is to be enabled
_prefix
  Pathname of directory to contain the Slurm files
_sysconfdir (or _slurm_sysconfdir)
  Pathname of directory containing the slurm.conf configuration file
with_munge
  Specifies the MUNGE (authentication library) installation location
with_ssl
  Specifies SSL library installation location

An example .rpmmacros file:

    # .rpmmacros
    # Override some RPM macros from /usr/lib/rpm/macros
    # Set Slurm-specific macros for unconventional file locations
    #
    %_enable_debug     "--with-debug"
    %_prefix           /opt/slurm
    %_sysconfdir       %{_prefix}/etc/slurm
    %_defaultdocdir    %{_prefix}/doc
    %with_munge        "--with-munge=/opt/munge"

### RPMs Installed

The RPMs needed on the head node, compute nodes, and slurmdbd node can vary by configuration, but here is a suggested starting point:

- Head Node (where the slurmctld daemon runs),
  Compute and Login Nodes
  - slurm
  - slurm-perlapi
  - slurm-slurmctld (only on the head node)
  - slurm-slurmd (only on the compute nodes)
- SlurmDBD Node
  - slurm
  - slurm-slurmdbd

## Daemons

slurmctld is sometimes called the "controller". It orchestrates Slurm activities, including queuing of jobs, monitoring node states, and allocating resources to jobs. There is an optional backup controller that automatically assumes control in the event the primary controller fails (see the High Availability section below). The primary controller resumes control whenever it is restored to service. The controller saves its state to disk whenever there is a change in state (see "StateSaveLocation" in Configuration section below). This state can be recovered by the controller at startup time. State changes are saved so that jobs and other state information can be preserved when the controller moves (to or from a backup controller) or is restarted.

We recommend that you create a Unix user slurm for use by slurmctld. This user name will also be specified using the SlurmUser in the slurm.conf configuration file. This user must exist on all nodes of the cluster. Note that files and directories used by slurmctld will need to be readable or writable by the user SlurmUser (the Slurm configuration files must be readable; the log file directory and state save directory must be writable).

The slurmd daemon executes on every compute node. It resembles a remote shell daemon to export control to Slurm. Because slurmd initiates and manages user jobs, it must execute as the user root.

If you want to archive job accounting records to a database, the slurmdbd (Slurm DataBase Daemon) should be used. We recommend that you defer adding accounting support until after basic Slurm functionality is established on your system. An Accounting web page contains more information.

slurmctld and/or slurmd should be initiated at node startup time per the Slurm configuration.

The slurmrestd daemon was introduced in version 20.02 and allows clients to communicate with Slurm via the REST API. This is installed by default, assuming the prerequisites are met. It has two run modes, allowing you to have it run as a traditional Unix service and always listen for TCP connections, or you can have it run as an Inet service and only have it active when in use.

### High Availability

Multiple SlurmctldHost entries can be configured, with any entry beyond the first being treated as a backup host. Any backup hosts configured should be on a different node than the node hosting the primary slurmctld. However, all hosts should mount a common file system containing the state information (see "StateSaveLocation" in the Configuration section below).

If more than one host is specified, when the primary fails the second listed SlurmctldHost will take over for it. When the primary returns to service, it notifies the backup. The backup then saves the state and returns to backup mode. The primary reads the saved state and resumes normal operation. Likewise, if both of the first two listed hosts fail the third SlurmctldHost will take over until the primary returns to service. Other than a brief period of non- responsiveness, the transition back and forth should go undetected.

Note that with an already running cluster, changing the order of the SlurmctldHost entries via `scontrol reconfigure` is not supported. The supported method is to drain and restart the cluster since running jobs may still go the prevous primary controller when completing and delay scheduling.

Prior to 18.08, Slurm used the "BackupAddr" and "BackupController" parameters for High Availability. These parameters have been deprecated and are replaced by "SlurmctldHost". Also see " SlurmctldPrimaryOnProg" and " SlurmctldPrimaryOffProg" to adjust the actions taken when machines transition between being the primary controller.

Any time the slurmctld daemon or hardware fails before state information reaches disk can result in lost state. Slurmctld writes state frequently (every five seconds by default), but with large numbers of jobs, the formatting and writing of records can take seconds and recent changes might not be written to disk. Another example is if the state information is written to file, but that information is cached in memory rather than written to disk when the node fails. The interval between state saves being written to disk can be configured at build time by defining SAVE_MAX_WAIT to a different value than five.

## Infrastructure

### User and Group Identification

There must be a uniform user and group name space (including UIDs and GIDs) across the cluster. It is not necessary to permit user logins to the control hosts (SlurmctldHost), but the users and groups must be resolvable on those hosts.

### Authentication of Slurm communications

All communications between Slurm components are authenticated. The authentication infrastructure is provided by a dynamically loaded plugin chosen at runtime via the AuthType keyword in the Slurm configuration file. The only currently supported authentication types is munge, which requires the installation of the MUNGE package. When using MUNGE, all nodes in the cluster must be configured with the same munge.key file. The MUNGE daemon, munged, must also be started before Slurm daemons. Note that MUNGE does require clocks to be synchronized throughout the cluster, usually done by NTP.

### MPI support

Slurm supports many different MPI implementations. For more information, see MPI.

### Scheduler support

Slurm can be configured with rather simple or quite sophisticated scheduling algorithms depending upon your needs and willingness to manage the configuration (much of which requires a database). The first configuration parameter of interest is PriorityType with two options available: basic (first-in-first-out) and multifactor. The multifactor plugin will assign a priority to jobs based upon a multitude of configuration parameters (age, size, fair-share allocation, etc.) and its details are beyond the scope of this document. See the Multifactor Job Priority Plugin document for details.

The SchedType configuration parameter controls how queued jobs are scheduled and several options are available.

- builtin will initiate jobs strictly in their priority order, typically (first-in-first-out)
- backfill will initiate a lower-priority job if doing so does not delay the expected initiation time of higher priority jobs; essentially using smaller jobs to fill holes in the resource allocation plan. Effective backfill scheduling does require users to specify job time limits.
- gang time-slices jobs in the same partition/queue and can be used to preempt jobs from lower-priority queues in order to execute jobs in higher priority queues.

For more information about scheduling options see Gang Scheduling, Preemption, Resource Reservation Guide, Resource Limits and Sharing Consumable Resources.

### Resource selection

The resource selection mechanism used by Slurm is controlled by the SelectType configuration parameter. If you want to execute multiple jobs per node, but track and manage allocation of the processors, memory and other resources, the cons_res (consumable resources) or cons_tres (consumable trackable resources) plugins are recommended. For more information, please see Consumable Resources in Slurm.

### Logging

Slurm uses syslog to record events if the `SlurmctldLogFile` and `SlurmdLogFile` locations are not set.

### Accounting

Slurm supports accounting records being written to a simple text file, directly to a database (MySQL or MariaDB), or to a daemon securely managing accounting data for multiple clusters. For more information see Accounting.

### Compute node access

Slurm does not by itself limit access to allocated compute nodes, but it does provide mechanisms to accomplish this. There is a Pluggable Authentication Module (PAM) for restricting access to compute nodes available for download. When installed, the Slurm PAM module will prevent users from logging into any node that has not be assigned to that user. On job termination, any processes initiated by the user outside of Slurm's control may be killed using an Epilog script configured in slurm.conf.

## Configuration

The Slurm configuration file includes a wide variety of parameters. This configuration file must be available on each node of the cluster and must have consistent contents. A full description of the parameters is included in the slurm.conf man page. Rather than duplicate that information, a minimal sample configuration file is shown below. Your slurm.conf file should define at least the configuration parameters defined in this sample and likely additional ones. Any text following a "#" is considered a comment. The keywords in the file are not case sensitive, although the argument typically is (e.g., "SlurmUser=slurm" might be specified as "slurmuser=slurm"). The control machine, like all other machine specifications, can include both the host name and the name used for communications. In this case, the host's name is "mcri" and the name "emcri" is used for communications. In this case "emcri" is the private management network interface for the host "mcri". Port numbers to be used for communications are specified as well as various timer values.

The SlurmUser must be created as needed prior to starting Slurm and must exist on all nodes in your cluster. The parent directories for Slurm's log files, process ID files, state save directories, etc. are not created by Slurm. They must be created and made writable by SlurmUser as needed prior to starting Slurm daemons.

A description of the nodes and their grouping into partitions is required. A simple node range expression may optionally be used to specify ranges of nodes to avoid building a configuration file with large numbers of entries. The node range expression can contain one pair of square brackets with a sequence of comma separated numbers and/or ranges of numbers separated by a "-" (e.g. "linux[0-64,128]", or "lx[15,18,32-33]"). Up to two numeric ranges can be included in the expression (e.g. "rack[0-63]_blade[0-41]"). If one or more numeric expressions are included, one of them must be at the end of the name (e.g. "unit[0-31]rack" is invalid), but arbitrary names can always be used in a comma separated list.

Node names can have up to three name specifications: NodeName is the name used by all Slurm tools when referring to the node, NodeAddr is the name or IP address Slurm uses to communicate with the node, and NodeHostname is the name returned by the command /bin/hostname -s. Only NodeName is required (the others default to the same name), although supporting all three parameters provides complete control over naming and addressing the nodes. See the slurm.conf man page for details on all configuration parameters.

Nodes can be in more than one partition and each partition can have different constraints (permitted users, time limits, job size limits, etc.). Each partition can thus be considered a separate queue. Partition and node specifications use node range expressions to identify nodes in a concise fashion. This configuration file defines a 1154-node cluster for Slurm, but it might be used for a much larger cluster by just changing a few node range expressions. Specify the minimum processor count (CPUs), real memory space (RealMemory, megabytes), and temporary disk space (TmpDisk, megabytes) that a node should have to be considered available for use. Any node lacking these minimum configuration values will be considered DOWN and not scheduled. Note that a more extensive sample configuration file is provided in etc/slurm.conf.example. We also have a web-based configuration tool which can be used to build a simple configuration file, which can then be manually edited for more complex configurations.

    #
    # Sample /etc/slurm.conf for mcr.llnl.gov
    #
    SlurmctldHost=mcri(12.34.56.78)
    SlurmctldHost=mcrj(12.34.56.79)
    #
    AuthType=auth/munge
    Epilog=/usr/local/slurm/etc/epilog
    JobCompLoc=/var/tmp/jette/slurm.job.log
    JobCompType=jobcomp/filetxt
    JobCredentialPrivateKey=/usr/local/etc/slurm.key
    JobCredentialPublicCertificate=/usr/local/etc/slurm.cert
    PluginDir=/usr/local/slurm/lib/slurm
    Prolog=/usr/local/slurm/etc/prolog
    SchedulerType=sched/backfill
    SelectType=select/linear
    SlurmUser=slurm
    SlurmctldPort=7002
    SlurmctldTimeout=300
    SlurmdPort=7003
    SlurmdSpoolDir=/var/spool/slurmd.spool
    SlurmdTimeout=300
    StateSaveLocation=/var/spool/slurm.state
    SwitchType=switch/none
    TreeWidth=50
    #
    # Node Configurations
    #
    NodeName=DEFAULT CPUs=2 RealMemory=2000 TmpDisk=64000 State=UNKNOWN
    NodeName=mcr[0-1151] NodeAddr=emcr[0-1151]
    #
    # Partition Configurations
    #
    PartitionName=DEFAULT State=UP
    PartitionName=pdebug Nodes=mcr[0-191] MaxTime=30 MaxNodes=32 Default=YES
    PartitionName=pbatch Nodes=mcr[192-1151]

## Security

Besides authentication of Slurm communications based upon the value of the AuthType, digital signatures are used in job step credentials. This signature is used by slurmctld to construct a job step credential, which is sent to srun and then forwarded to slurmd to initiate job steps. This design offers improved performance by removing much of the job step initiation overhead from the slurmctld daemon. The digital signature mechanism is specified by the CredType configuration parameter and the default mechanism is MUNGE.

### Authentication

Authentication of communications (identifying who generated a particular message) between Slurm components can use a different security mechanism that is configurable. You must specify one "auth" plugin for this purpose using the AuthType configuration parameter. Currently, only one authentication plugin is supported: auth/munge. MUNGE should be installed in order to get properly authenticated communications. We recommend the use of MUNGE. The configure script in the top-level directory of this distribution will determine which authentication plugins may be built. The configuration file specifies which of the available plugins will be utilized.

### Pluggable Authentication Module (PAM) support

A PAM module (Pluggable Authentication Module) is available for Slurm that can prevent a user from accessing a node which he has not been allocated, if that mode of operation is desired.

## Starting the Daemons

For testing purposes you may want to start by just running slurmctld and slurmd on one node. By default, they execute in the background. Use the -D option for each daemon to execute them in the foreground and logging will be done to your terminal. The -v option will log events in more detail with more v's increasing the level of detail (e.g. -vvvvvv). You can use one window to execute "slurmctld -D -vvvvvv", a second window to execute "slurmd -D -vvvvv". You may see errors such as "Connection refused" or "Node X not responding" while one daemon is operative and the other is being started, but the daemons can be started in any order and proper communications will be established once both daemons complete initialization. You can use a third window to execute commands such as "srun -N1 /bin/hostname" to confirm functionality.

Another important option for the daemons is "-c" to clear previous state information. Without the "-c" option, the daemons will restore any previously saved state information: node state, job state, etc. With the "-c" option all previously running jobs will be purged and node state will be restored to the values specified in the configuration file. This means that a node configured down manually using the scontrol command will be returned to service unless noted as being down in the configuration file. In practice, Slurm consistently restarts with preservation.

## Administration Examples

scontrol can be used to print all system information and modify most of it. Only a few examples are shown below. Please see the scontrol man page for full details. The commands and options are all case insensitive.

Print detailed state of all jobs in the system.

    adev0: scontrol
    scontrol: show job
    JobId=475 UserId=bob(6885) Name=sleep JobState=COMPLETED
       Priority=4294901286 Partition=batch BatchFlag=0
       AllocNode:Sid=adevi:21432 TimeLimit=UNLIMITED
       StartTime=03/19-12:53:41 EndTime=03/19-12:53:59
       NodeList=adev8 NodeListIndecies=-1
       NumCPUs=0 MinNodes=0 OverSubscribe=0 Contiguous=0
       MinCPUs=0 MinMemory=0 Features=(null) MinTmpDisk=0
       ReqNodeList=(null) ReqNodeListIndecies=-1

    JobId=476 UserId=bob(6885) Name=sleep JobState=RUNNING
       Priority=4294901285 Partition=batch BatchFlag=0
       AllocNode:Sid=adevi:21432 TimeLimit=UNLIMITED
       StartTime=03/19-12:54:01 EndTime=NONE
       NodeList=adev8 NodeListIndecies=8,8,-1
       NumCPUs=0 MinNodes=0 OverSubscribe=0 Contiguous=0
       MinCPUs=0 MinMemory=0 Features=(null) MinTmpDisk=0
       ReqNodeList=(null) ReqNodeListIndecies=-1

Print the detailed state of job 477 and change its priority to zero. A priority of zero prevents a job from being initiated (it is held in "pending" state).

    adev0: scontrol
    scontrol: show job 477
    JobId=477 UserId=bob(6885) Name=sleep JobState=PENDING
       Priority=4294901286 Partition=batch BatchFlag=0
       more data removed....
    scontrol: update JobId=477 Priority=0

Print the state of node adev13 and drain it. To drain a node, specify a new state of DRAIN, DRAINED, or DRAINING. Slurm will automatically set it to the appropriate value of either DRAINING or DRAINED depending on whether the node is allocated or not. Return it to service later.

    adev0: scontrol
    scontrol: show node adev13
    NodeName=adev13 State=ALLOCATED CPUs=2 RealMemory=3448 TmpDisk=32000
       Weight=16 Partition=debug Features=(null)
    scontrol: update NodeName=adev13 State=DRAIN
    scontrol: show node adev13
    NodeName=adev13 State=DRAINING CPUs=2 RealMemory=3448 TmpDisk=32000
       Weight=16 Partition=debug Features=(null)
    scontrol: quit
    Later
    adev0: scontrol
    scontrol: show node adev13
    NodeName=adev13 State=DRAINED CPUs=2 RealMemory=3448 TmpDisk=32000
       Weight=16 Partition=debug Features=(null)
    scontrol: update NodeName=adev13 State=IDLE

Reconfigure all Slurm daemons on all nodes. This should be done after changing the Slurm configuration file.

    adev0: scontrol reconfig

Print the current Slurm configuration. This also reports if the primary and secondary controllers (slurmctld daemons) are responding. To just see the state of the controllers, use the command ping.

    adev0: scontrol show config
    Configuration data as of 2019-03-29T12:20:45
    ...
    SlurmctldAddr           = eadevi
    SlurmctldDebug          = info
    SlurmctldHost[0]        = adevi
    SlurmctldHost[1]        = adevj
    SlurmctldLogFile        = /var/log/slurmctld.log
    ...

    Slurmctld(primary) at adevi is UP
    Slurmctld(backup) at adevj is UP

Shutdown all Slurm daemons on all nodes.

    adev0: scontrol shutdown

## Upgrades

Background: The Slurm version number contains three period-separated numbers that represent both the major Slurm release and maintenance release level. The first two parts combine together to represent the major release, and match the year and month of that major release. The third number in the version designates a specific maintenance level: year.month.maintenance-release (e.g. 20.02.2 is major Slurm release 20.02, and maintenance version 2). Thus version 21.08.x was initially released in August 2021. Changes in the RPCs (remote procedure calls) and state files will only be made if the major release number changes, which typically happens about every nine months. A list of most recent major Slurm releases is shown below.

- 20.02.x (Released February 2020)
- 20.11.x (Released November 2020)
- 21.08.x (Released August 2021)

Slurm's MPI libraries may also change if the major release number changes, requiring applications be re-linked (behavior may vary depending upon the MPI implementation used and the specific Slurm changes between releases). Locally developed Slurm plugins may also require modification. Slurm daemons will support RPCs and state files from the two previous major releases (e.g. a version 21.08.x SlurmDBD will support slurmctld daemons and commands with a version of 21.08.x, 20.11.x, or 20.02.x). This means that upgrading at least once each year is recommended. Otherwise, intermediate upgrades will be required to preserve state information. Changes in the mainenance release number generally represent only bug fixes, but may also include minor enhancements.

If the SlurmDBD daemon is used, it must be at the same or higher major release number as the Slurmctld daemons. In other words, when changing the version to a higher release number (e.g from 20.02.x to 20.11.x) always upgrade the SlurmDBD daemon first. Database table changes may be required for the upgrade, for example adding new fields to existing tables. If the database contains a large number of entries, the SlurmDBD daemon may require tens of minutes to update the database and be unresponsive during this time interval.

Before upgrading SlurmDBD it is strongly recommended to make a backup of the database. We recommend you only backup the database used by slurmdbd to limit the time spent creating the backup and avoid potential problems when restoring from a file that contains multiple databases. If using mysqldump, the default behavior is to lock the tables, which can cause issues if SlurmDBD is still trying to send updates to the database. If you must make a backup while the cluster is still active we recommend you use the --single-transaction flag with mysqldump to avoid locking tables. This will dump a consistent state of the database without blocking any applications. Note that in order for this flag to have the desired effect you must be using the InnoDB storage engine (specified by default when Slurm automatically creates any table) (e.g. mysqldump --single-transaction --databases slurm_acct_db > backup.sql).

Our recommendation is to first stop the SlurmDBD daemon and then backup the database (using a tool like mysqldump, Percona xtrabackup or other) before proceeding with the upgrade. Note that requests intended for SlurmDBD from Slurmctld will be queued while SlurmDBD is down, but the queue size is limited and you should monitor the DBD Agent Queue size with the sdiag command.

The slurmctld daemon must also be upgraded before or at the same time as the slurmd daemons on the compute nodes. Generally, upgrading Slurm on all of the login and compute nodes is recommended, although rolling upgrades are also possible (i.e. upgrading the head node(s) first then upgrading the compute and login nodes later at various times). Also see the note above about reverse compatibility.

Almost every new major release of Slurm (e.g. 20.02.x to 20.11.x) involves changes to the state files with new data structures, new options, etc. Slurm permits upgrades to a new major release from the past two major releases, which happen every nine months (e.g. 20.02.x or 20.11.x to 21.08.x) without loss of jobs or other state information. State information from older versions will not be recognized and will be discarded, resulting in loss of all running and pending jobs. State files are not recognized when downgrading (e.g. from 20.11.x to 20.02.x) and will be discarded, resulting in loss of all running and pending jobs. For this reason, creating backup copies of state files (as described below) can be of value. Therefore when upgrading Slurm (more precisely, the slurmctld daemon), saving the StateSaveLocation (as defined in slurm.conf) directory contents with all state information is recommended. If you need to downgrade, restoring that directory's contents will let you recover the jobs. Jobs submitted under the new version will not be in those state files, but it can let you recover most jobs. An exception to this is that jobs may be lost when installing new pre-release versions (e.g. 20.02.0-pre1 to 20.02.0-pre2). Developers will try to note these cases in the NEWS file. Contents of major releases are also described in the RELEASE_NOTES file.

A common approach when performing upgrades is to install the new version of Slurm to a unique directory and use a symbolic link to point the directory in your PATH to the version of Slurm you would like to use. This allows you to install the new version before you are in a maintenance period as well as easily switch between versions should you need to roll back for any reason. It also avoids potential problems with library conflicts that might arise from installing different versions to the same directory.

The libslurm.so version is increased every major release. So things like MPI libraries with Slurm integration should be recompiled. Sometimes it works to just symlink the old .so name(s) to the new one, but this has no guarantee of working.

Be mindful of your configured SlurmdTimeout and SlurmctldTimeout values. If the Slurm daemons are down for longer than the specified timeout during an upgrade, nodes may be marked DOWN and their jobs killed. You can either increase the timeout values during an upgrade or ensure that the slurmd daemons on compute nodes are not down for longer than SlurmdTimeout. The recommended upgrade order is as follows:

1. Shutdown the slurmdbd daemon.
2. Backup the Slurm database using mysqldump (or similar tool), e.g. mysqldump --databases slurm_acct_db > backup.sql. You may also want to take this opportunity to verify that the innodb_buffer_pool_size in my.cnf is at least 128M.
3. Upgrade the slurmdbd daemon.
4. Restart the slurmdbd daemon.

- NOTE: The first time slurmdbd is started after an upgrade it will take some time to update existing records in the database. If slurmdbd is started with systemd, it may think that slurmdbd is not responding and kill the process when it reaches its timeout value, which causes problems with the upgrade. We recommend starting slurmdbd by calling the command directly rather than using systemd when performing an upgrade.

5. Increase configured SlurmdTimeout and SlurmctldTimeout values and execute "scontrol reconfig" for them to take effect.
6. Shutdown the slurmctld daemon(s).
7. Shutdown the slurmd daemons on the compute nodes.
8. Copy the contents of the configured StateSaveLocation directory (in case of any possible failure).
9. Upgrade the slurmctld and slurmd daemons.
10. Restart the slurmd daemons on the compute nodes.
11. Restart the slurmctld daemon(s).
12. Validate proper operation.
13. Restore configured SlurmdTimeout and SlurmctldTimeout values and execute "scontrol reconfig" for them to take effect.
14. Destroy backup copies of database and/or state files.

NOTE: It is possible to update the slurmd daemons on a node-by-node basis after the slurmctld daemon(s) are upgraded, but do make sure their down time is below the SlurmdTimeout value.

If you have built your own version of Slurm plugins, they will likely need modification to support a new version of Slurm. It is common for plugins to add new functions and function arguments during major updates. See the RELEASE_NOTES file for details.

## FreeBSD

FreeBSD administrators can install the latest stable Slurm as a binary package using:

    pkg install slurm-wlm

Or, it can be built and installed from source using:

    cd /usr/ports/sysutils/slurm-wlm && make install

The binary package installs a minimal Slurm configuration suitable for typical compute nodes. Installing from source allows the user to enable options such as mysql and gui tools via a configuration menu.

Last modified 7 December 2021