Batch System PBSPro (vulcan)

Introduction

Applications cannot be run directly from the login node on the compute nodes of the system. The only way to get access to the compute nodes of the system is to use the batch system. Therefore a batch script has to be provided, which includes all the necessary commands to run the application. The installed batch system is PBSPro

You generally interact with the batch system in two ways: (1) through options specified in job submission scripts (these are detailed below in the examples) and (2) by using PBSPro commands on the login nodes.

There are three key commands used to interact with PBSPro:

qsub: used to submit your batch script to the system to be executed as a batch job
qstat: to display information about submitted batch jobs
qdel: to discard a submitted or running batch job

Check the man pages of the individual commands as well as the man page for PBSPro on the login node for more information:

man qsub
man qstat
man qdel

man pbs_professional

If you are looking for in depth information consult the User Guide in the PBS Pro documentation.

Requesting Resources using batch system

Resources are allocated to jobs both by explicitly requesting them and by applying specified defaults.
Jobs explicitly request resources either at the host level in chunks defined in a selection statement, or in job-wide resource requests.

job wide request:
```
   qsub ... -l <resource name>=<value> 
```
The only resources that can be in a job-wide request are server-level or queue-level resources, such as walltime.
selection statement:
```
   qsub ... -l select=<chunks> 
```
The only resources that can be requested in chunks are host-level resources, such as mem and ncpus. A chunk is the smallest set of resources that will be allocated to a job. It is one or more resource_name=value statements separated by a colon, e.g.:
```
ncpus=2:mem=32GB
```
```
A  selection statement is of the form:
```
```
  -l select=[N:]chunk[+[N:]chunk ...] 
```
Note: If N is not specified, it is taken to be 1. No spaces are allowed between chunks.

Warning: all requested cluster nodes will be exclusively allocated by 1 job. The default nodes can not be shared by multiple jobs. The allocated nodes of your job will be accounted completely, even though your job uses the allocated nodes only partial

Node types

You have to specify the resources you need for your batch job. These resources are specified by including them in the -l argument (selection statement and job-wide resources) on the qsub command or in the PBS job script. The 2 important resources you have to specify are number of nodes of a specific node type in the selection statement and the walltime in the job-wide resource request you need for this job:

select=<number of nodes>:<node_resource_variable=type>

node_type

node_type_cpu

node_type_mem

node_type_core

localscratch

localscratch

linkspeed

**Available node types:**
node_type	node_type_cpu	node_type_mem	node_type_core	Graphic / Accelerator	localscratch	linkspeed	describtion	notes	# of nodes (vulcan)	# of nodes (vulcan2)
clx-21	CascadeLake@2.10GHz	384gb	40c		1.8TB	HDR-100	Intel Xeon Gold 6230 @ 2.5GHz, CascadeLake, 384GB memory, 1.8TB /localscratch	2 x 20 core-CPU per node	8	0
clx-25, clx	CascadeLake@2.50GHz	384gb	40c			HDR-100	Intel Xeon Gold 6248 @ 2.5GHz, CascadeLake, 384GB memory	2 x 20 core-CPU per node	96	0
hsw	Haswell@2.50GHz	128gb	24c			QDR	Intel Xeon E5-2680v3 @ 2.50GHz, Haswell, 128GB memory	2 x 12 core-CPU per node	0	192 (1 is in shared mode)
skl	Skylake@2.0GHz	192gb	40c			EDR	Intel Xeon Gold 6138 @ 2.00GHz, Skylake, 92GB memory	2 x 20 core-CPU per node	72	0
smp1500	Skylake@2.40GHz	1536gb	40c			FDR	Intel Gold 6148 @ 2.40GHz, Skylake, 1.5TByte memory	2 x 20 core-CPU per node will be shared with other jobs! Please use `"qsub -q smp -l select=1:node_type=smp ..."`	1 (shared)	0
aurora	Skylake@2.60GHz	192gb	24c	8x NEC Aurora vector CPUs		EDR	2.60GHz, Skylake, 192GB memory, 8 NEC Aurora TSUBASA nodes	2 x 12 core-CPU per node Please use `"qsub -q vector -l select=1:node_type=aurora ..."`	8	0
p100	Broadwell@3.00GHz	1024gb	24c	Nvidia Tesla P100	11TB	QDR	Cuda Node with Nvidia Tesla P100 Intel Xeon E5-2687Wv4 @ 3.0GHz, Broadwell, 1TB memory, 11TB local SSD scratch disk	2 x 8 core-CPU per node reserved for special users! Please use `"qsub -q R_i1 -l select=1:node_type=p100 ..."`	3	0
visamd	Skylake@2.60GHz	96gb	8c	AMD Radeon PRO WX 8200		HDR-100	Graphic Node with AMD Radeon PRO WX 8200 Intel Xeon Silver 4112 @ 2.6GHz, Skylake, 96GB memory	2 x 4 core-CPU per node only 1 node per job! Please use `"qsub -q vis -l select=1:node_type=visamd ..."`	6	0
visnv	Skylake@2.60GHz	96gb	8c	Nvidia Quadro RTX 4000		HDR-100	Graphic Node with Nvidia Quadro RTX 4000 Intel Xeon Silver 4112 @ 2.6GHz, Skylake, 96GB memory	2 x 6 core-CPU per node only 1 node per job! (1 node is reserved for special users) Please use `"qsub -q vis -l select=1:node_type=visnv ..."`	2	1
genoa	Zen4@2.7GHz	768gb	64c			HDR-100	AMD compute node with 2x AMD Epyc 9334 Genoa, 2.7GHz base, 64 cores total, 768GB DDR5	2 x 32 core-CPU	60	0
genoa-smp	Zen4@2.7GHz	3072gb	64c			HDR-100	AMD shared node with 2x AMD Epyc 9334 Genoa, 2.7GHz base, 64 cores total, 3072GB DDR5	2 x 32 core-CPU per node will be shared with other jobs! Please use `"qsub -q smp -l select=1:node_type=smp ..."`	2 (shared)	0
genoa-gpu	Zen4@3.0GHz	768gb	32c	Nvidia A30 with 24GB HBM2e	3.8TB NVMe	HDR-100	GPU Node 2x AMD Epyc 9124 Genoa, 3.0GHz base, 32 cores total, 768GB DDR5, 3.8TB NVMe, 1x Nvidia A30 with 24GB HBM2e	2 x 16 core-CPU	0	0
visp100	Broadwell@3.20GHz	256gb	16c	Nvidia Tesla P100		FDR	Cuda Node with Nvidia Tesla P100 Intel Xeon E5-2667v4 @ 3.2GHz, Broadwell, 256GB memory	2 x 8 core-CPU per node only 1 node per job! Please use `"qsub -q vis -l select=1:node_type=visp100 ..."`	10	0

Multi node type job can also be specified using a +:

select=1:node_type=clx-25:node_type_mem=384gb+3:node_type=skl:node_type_mem=192gb:node_type_core=40c

The example above will allocate 1 clx-25 node with 384 GB memory and 3 skl nodes (the 40 cores type) with 192 GB memory.

To allocate special nodes with local disk you can use the special node resource variable localscratch:

select=1:node_type=clx-21:localscratch=1800GB

walltime=<time>

Batch Mode

Production jobs are typically run in batch mode. Batch scripts are shell scripts containing flags and commands to be interpreted by a shell and are used to run a set of commands in sequence.

The number of required nodes, cores, wall time and more can be determined by the parameters in the job script header with "#PBS" before any executable commands in the script.

#!/bin/bash
#PBS -N job_name
#PBS -l select=2:node_type=clx:mpiprocs=40
#PBS -l walltime=00:20:00             
  
# Change to the direcotry that the job was submitted from
cd $PBS_O_WORKDIR

# using the INTEL MPI module
module load mpi/impi

# Launch the parallel mpi application (compiled with intel mpi) to the allocated compute nodes
mpirun -np 48  ./my_mpi_executable arg1 arg2 > my_output_file 2>&1

The job is submitted by the qsub command (all script head parameters #PBS can also be adjusted directly by qsub command options).

 qsub my_batchjob_script.pbs

Setting qsub options on the command line will overwrite the settings given in the batch script:

 qsub -N other_name -l select=2:node_type=clx:mpiprocs=40 -l walltime=00:20:00 my_batchjob_script.pbs

The batch script is not necessarily granted resources immediately, it may sit in the queue of pending jobs for some time before its required resources become available.
At the end of the execution output and error files are returned to your HOME directory
This example will run your executable "my_mpi_executable" in parallel with 80 MPI processes (mpiprocs=40 is the number of MPI processes on each node) . The batch system will allocate 2 nodes to your job for a maximum time of 20 minutes and place 40 processes on each node. The batch systems allocates nodes exclusively only for one job. After the walltime limit is exceeded, the batch system will terminate your job. The mpirun example above will start the parallel executable "my_mpi_executable" with the arguments "arg1" and "arg2". The job will be started using 80 MPI processes with 40 processes placed on each of your allocated nodes. You need to have nodes allocated by the batch system (qsub) before starting mpirun.

Note:

While your job is running (in Batch Mode), STDOUT and STDERR are written to a file or files in a system directory and the output is copied to your submission directory (PBS_O_WORKDIR) only after the job completes. Specifying the

qsub -koed my_batchjob_script.pbs

option here and redirecting the output to a file (see example above) makes it possible for you to view STDOUT and STDERR of your job scripts while the job is running.

Interactive batch Mode

Interactive mode is typically used for debugging or optimizing code but not for running production code. To begin an interactive session, use the "qsub -I" command:

 qsub -I -l select=2:node_type=clx:ncpus=40:mpiprocs=40 -l walltime=00:30:00

If the requested resources are available and free (in the example above: 2 clx nodes/40 cores each, 30 minutes, prepared for 40 mpi processes on each node), then you will get a new session on the jobs head node for your requested resources. Now you have to use the mpirun command to launch your parallel application to the allocated compute nodes. When you are finished, enter logout to exit the batch system and return to the normal command line.

PBS_NODEFILE (MPI usage of multi-socket nodes and multi-core cpus)

In most MPI environments, the PBS_NODEFILE will be usefull to start the correct number of mpi processes on each allocated node. The jobs ${PBS_NODEFILE} contents depends on the number of MPI processes for each requested chunk. Inside a select statement of each chunk you can define a mpiprocs option (Type: integer). The number of lines in PBS_NODEFILE is the sum of the values of mpiprocs for all chunks requested by the job. For each chunk with mpiprocs=P, the host name for that chunk is written to the PBS_NODEFILE P times.

Example:

 qsub -l select=2:node_type=skl ./myscript

The batch system allocates two node of type skl. The file ${PBS_NODEFILE} contains:

 node1
 node2

If the chunk request has the option mpiprocs defined, then it is possible to allocate the defined PE's on a node. This option especially allow OpenMPI to place the MPI processes of ranks on a shared node or alternatively on distributed nodes.

select example with 2 chunk requests (seperated by '+'):

 qsub -l select=2:skl:mpiprocs=2+1:node_type=skl:mpiprocs=3 ./myscript

The batch system allocates 2 nodes of type skl each for 2 PE's and 1 node of type skl for 3 PE's. Then the file ${PBS_NODEFILE} contains:

 node1
 node1
 node2
 node2
 node3
 node3
 node3

Defaults for Ressource Requests

If you don't set the resources for your job request, then you will get default resource limits for your job.

resource	value	notes
select	1
mpiprocs	1

Please select your resource requests carefull.

To have the same environmental settings (exported environment) of your current session in your batchjob, the qsub command needs the option argument -V.

Run job on other Account ID

There are Unix groups associated to the project account ID (ACID). To run a job on a non-default project budget, the groupname of this project has to be passed in the group_list:

qsub -l select=1:node_type=clx -W group_list=<groupname>

To get your available groups:

id -Gn

Warning: note that this procedure is neither applicable nor necessary for the default project (associated to the primary group), printed with "id -gn".

Usage of a Reservation

For nodes which are reserved for special groups or users, you need to specify additional the queue which is intended for this reservation:

E.g. a reservation of some nodes is bound to the queue named workday:

qsub -q workday -l select=1:node_type=clx -l walltime=1:00 testjob.cmd

Following reservations are availalble at the moment:

reservation	resources	queue	limitations	notes
S150017	1 node of node_type clx (40 cores, 384GB)	workday for routing to S150017	valid on Mo-Fr 6:00-18:00, user- and group-run limits, walltime limit, nodecount limits will be set for jobs using this reservation	This daytime reservation should be used for jobs with a short walltime

Job Arrays

Job arrays are groups of similar jobs. Those jobs usually have slightly different parameters which depend on the current job index. This job index will be available in the $PBS_ARRAY_INDEX variable, which can be used in job scripts to calculate or generate any kind of job-specific (input)data.

Job arrays can be requested with

qsub -J <range> <my_array_jobscript>

range is specified in the form X-Y[:Z] where X is the first index, Y is the upper bound on the indices and Z is the stepping factor. For example, 2-7:2 will produce indices of 2, 4, and 6. If Z is not specified, it is taken to be 1.

Note:

Job arrays cannot be interactive

Job arrays are automatically marked as rerunnable

Examples

Examples for PBS options in job scripts

You can submit batch jobs using qsub. A very simple qsub script for a MPI job with PBSPro directives (#PBS ...) for the options of qsub looks like this:

#!/bin/bash
#
# Simple PBS batch script that reserves two exclusive Skylake nodes
# and runs only one MPI process on each node (in total 2 MPI processes)
# The walltime is 10min
#
#PBS -l select=2:node_type=skl:mpiprocs=1
#PBS -l walltime=00:10:00

### go to directory where your job request was submitted 
cd $PBS_O_WORKDIR

### load for example the Intel MPI environment
module load mpi/impi

### run you parallel application on the allocated nodes
mpirun -np 2 ./mpitest

Warning:

you have to specify a shell in the first line of your batch script
you have to specify the number of nodes you need and the node type
you have to specify the walltime the job needs
allocated nodes will not be shared with other jobs, even though you uses the nodes only partial

If you want to use four MPI processes on each node this can be done like this:

#!/bin/bash
#
# Simple PBS batch script that reserves two exclusive Skylake nodes
#  and runs four MPI process on each node  (in total 8 MPI processes)
# The walltime is 10min
#
#PBS -l select=2:node_type=skl:mpiprocs=4
#PBS -l walltime=00:10:00

### go to directory where your job request was submitted
cd $PBS_O_WORKDIR

### load for example the Intel MPI environment
module load mpi/impi

### run you parallel application on the allocated nodes
mpirun -np 8 ./mpitest

If you need 2h wall time and one node you can use the following script:

#!/bin/bash
#
# Simple PBS batch script that runs a scalar job 
# on 1 Skylake node using 2h
#
#PBS -l select=1:node_type=skl,walltime=2:00:00
cd $PBS_O_WORKDIR
./my_executable

Examples for starting batch jobs:

Starting a script with all options specified inside the script file
```
qsub <script>
```

Starting a script using 3 nodes of node_type 'skl' and a real time of 2 hours:
```
qsub -l select=3:node_type=skl,walltime=2:00:00 <script>
```

Starting a script using 5 cluster nodes of node_type 'clx' using 10 processors on each node:
```
qsub -l select=5:node_type=clx:mpiprocs=10,walltime=2:00:00 <script>
```

Starting a interactive batch job using 5 clx nodes with a job real time of 300 seconds:
```
qsub -I -l select=5:node_type=clx,walltime=300
```
Note: For interactive Batch jobs, you don't need a script.sh file. If the requested resources are available, you will get an interactive shell on one of the allocated compute nodes. Which nodes are allocated can be shown with the command
```
cat $PBS_NODEFILE 
```
on the batch job shell or with the PBS status command
```
qstat -n <jobid>
```
on the master node.
You can log in from the frontend or any assigned node to all other assigned nodes by
```
export PBS_JOBID=<jobid>
ssh <nodename>
```
<jobid> is of format (number.batchserver e.g: 123456.cl1intern).
If you exit the automatically established interactive shell to the node, it will be assumed that you finished your job and all other connections to the nodes will be terminated.

Other possibilities to request cluster nodes. You want 4 nodes with a minimum of 40 cores regardless which type of nodes. And you want to run 40 MPI processes on each of the 4 nodes:
```
qsub -l select=4:ncpus=40:mem=128g:mpiprocs=40 <script>
```
Then its possible you will get a mix of 4 nodes composed of clx and skl node types.

Starting a script which should run on other Account ID: First you have to know which Account ID's (groupnames) are valid for your login:
```
id
```
Choose a valid groupname for your job (abc12345 will serve as a placeholder here):
```
qsub -l select=5:node_type=clx,walltime=300 -W group_list=abc12345
```

Get the batch job status

Available commands

qstat [options]
nstat
batchstat [options]

For detailed informations, see man pages:

nstat -h
batchstat -h
man qstat
man pbsnodes

Examples

(query status of jobs owned by other users has been prohibited!)

qstat -a

list all batch jobs (anonymous)

batchstat

lists all batch queues with resource limit settings:

qstat -q

lists node information of one of your batch job ID:

qstat -n <JOB_ID>

lists detailed information of one of your batch job ID:

qstat -f <JOB_ID>

Displays estimated start time for your queued jobs

qstat -T <JOB_ID>

Displays status information for your jobs, job arrays, and subjobs:

qstat -t <JOB_ID>

lists information of the PBS node status:

pbsnodes -a
pbsnodes -l

gives informatioin of PBS node and job status:

nstat
batchstat

ssh from login nodes to your allocated nodes of your job

You can only connect to nodes that belongs to you, that are, the allocated nodes of your jobs. To log in to this nodes via ssh from the login nodes (frontend nodes) you have to set the environment PBS_JOBID. First find your running jobid's and the nodes which belongs to the jobs:

 qstat -rnw

Next step is setting the environment PBS_JOBID on the login node:

 export PBS_JOBID=<JOB ID>

(the <JOB ID> is in form of 123456.cl5intern)
Now you are able to login form login node via ssh to the allocated nodes of your job with the corresponding jobid.

DISPLAY: X11 applications on interactive batch jobs

For X11 applications you need to have SSH X11 Forwarding enabled. This is usually activated per default. But to be sure you can set 'ForwardX11 yes' in your $HOME/.ssh/config. To have the same DISPLAY of your current session in your batchjob, the qsub command needs the option argument -X.

frontend> qsub -q vis -l select=1:node_type=fx5800,walltime=300 -X -I

Note:

DISPLAY variable in submission environment must be set to desired display.

Can be used with interactive jobs only: must be used with -I

Cannot be used with -v DISPLAY

X server on compute nodes

In general, no X server process is running on the compute nodes! For example to run a window manger on the compute nodes like icewm you need an X server. Some visualisation nodes have a graphic card installed (see here) on which an X server can be started inside the batch job by your self:

 HLRS-startX

This tool start an X server and returns the DISPLAY port on which the server is started. You can also use:

 get-X-display-port

to get the DISPLAY port for your running X server. To use the X server in your application you have to use the environment:

 export DISPLAY=:<port>

Alternatively see Graphic_Environment

Container, singularity, AI

Solving problems using artificial intelligence, usually you need nodes equipped with fast local disks and GPU's. Some nodes (node_type=clx-ai) are able to run singularity containers. To be able to start singularity container, the nodes have to be prepared before your batch job starts. You can do this by a resource request ('UNS=True') at your batch submission:

 qsub -l select=1:node_type=clx-ai:UNS=True,walltime=300 <mybatchjob>

Note: Only the nodes with node_type=clx-ai are able to run singularity container!

More about singularity container software can be found here: Cray Urika CS software stack

NEC vector CPU's Aurora

To use the NEC vector CPU's you need to submit your jobs to a special Queue "vector":

 qsub -q vector -l select=1:node_type=aurora,walltime=300 <mybatchjob>

More Details about NEC Auora can be found here (Aurora Tsubasa Platform).

Queue Policies and Limitations

Different job queues are available for efficient resource usage.

In most cases users do not need to declare a job queue with the qsub command. Jobs are sorted to the right class automatically. In the following the definition for each job queue is given. In general jobs with a Duration up to 24 hours and half of the available resources can be submitted. Some special resources like nodes with graphics or very large memory, (job sharing nodes) are only available for special queues which have to be declared with the qsub command. For larger jobs or for special job requirements different restrictions are in place respectively you have to consult the project team

Each limit settings and policies could be changed in future to adjust the cluster usage for new user requirements.

At the moment following queues and policies are defined:

route (default)

If users don't declare a queue on qsub submission, then the jobs default queue will be this. The "route" queue is a routing queue with final destinations for the industrial user jobs and the standard jobs depends on users/groups and the requested resources. The destination queues of "route" for standard jobs (academic users) are:

single

This queue is available for all single node jobs.

resource	min	max	note
walltime		24 hours
available nodes		1 per job (64 in total)	only single node jobs
priority			low
joblimit		20 per user, 30 per group

normal

This is for all regular parallel jobs using 2 nodes and more.

resource	min	max	note
walltime		24 hours
available nodes	2	384 per job (425 in total)
priority			normal
joblimit		20 per user

test

This queue is for tests and development with restricted resources needs. The jobs in this queue are expected to deliver results after very short time. It's forbidden to use this queue for production jobs. Users have to declare this queue with the qsub submission.

resource	min	max	note
walltime		25 minutes
available nodes		40
priority			very high
joblimit		1 per user (4 for ALL)

interactive

This queue is also only for batch jobs in interactive batch mode which can also be for tests and development. Users can not declare this queue with the qsub submission. But all interactive batch jobs will be routed to this queue automatically.

resource	min	max	note
walltime		8 hours
available nodes		32	only for job in interactive batch mode
priority			very high
joblimit		2 per user

vis

This queue is only available for jobs using graphic nodes. It can also be used in interactive batch mode. Only the nodes with a graphic card installed are available with this queue. Users have to declare this queue with the qsub job submission.

resource	min	max	note
walltime		10 hours
available nodes		1 per job (4 in total)	only nodes with graphic cards
priority			high
joblimit		2 per user, 4 per group

Job Run Limitations

The maximum time limit for a Job is 24hours.
User limits:
- limited number of jobs of one user that can run at the same time
- in total a user can only allocate 384 nodes.
User Group limits:
- limited number of jobs of users in the same group that can run at the same time
Batch Queue limits of all user jobs:
- not all nodes / node types are available on each queue (visualisation nodes can not be used in multi node job queues)
- The number of jobs for each user in the different job queues are restricted. If you reach this number you can submit further jobs when prior jobs have ended.
  - (If more jobs are submitted than allowed for one job queue the old ones will be placed in the dispatcher queue 'route' and will move up in the proper destination queue after jobs from this user in the corresponding queue have ended. The waiting queue for each user will take up to 10 jobs. With this it is possible to submit job ahead.)

Queues with extended wall time limits

are not available in general. This Queue spec1 is available for Jobs, which can not run within the 24h timeframe. Access to this queue is only granted by passing an evaluation process. Following rules apply to this queue:

Jobs may be killed for operation reasons at any time.
Jobs will be accounted in any case. This is also true if the job has to be terminated for operational reasons.
Joblimit per Group = 1
Joblimit per user = 1
Total number of nodes used for this queue = 64
Only general compute node types available, no visualisation or special node types
Low scheduling priority
Max walltime 96h

Batch System PBSPro (vulcan)

Contents

Introduction

Requesting Resources using batch system

Node types

Batch Mode

Interactive batch Mode

PBS_NODEFILE (MPI usage of multi-socket nodes and multi-core cpus)

Defaults for Ressource Requests

Run job on other Account ID

Usage of a Reservation

Job Arrays

Examples

Examples for PBS options in job scripts

Examples for starting batch jobs:

Get the batch job status

ssh from login nodes to your allocated nodes of your job

DISPLAY: X11 applications on interactive batch jobs

X server on compute nodes

Container, singularity, AI

NEC vector CPU's Aurora

Queue Policies and Limitations

route (default)

single

normal

test

interactive

vis

Job Run Limitations

Queues with extended wall time limits

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