Batch System PBSPro (vulcan)

Introduction

The only way to start a job (parallel or single node) on the compute nodes of this system is to use the batch system. The installed batch system is PBSPro.

Writing a submission script is typically the most convenient way to submit your job to the batch system. You generally interact with the batch system in two ways: through options specified in job submission scripts (these are detailed below in the examples) and by using PBSPro commands on the login nodes. There are three key commands used to interact with PBSPro:

• qsub
• qstat
• qdel

Check the man page of PBSPro for more advanced commands and options

 man pbs_professional

---

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.

Format:
• 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:

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

To distinguish between different nodes 4 node resource variables are assigned to each node. The node_type, node_type_cpu, node_type_mem and node_type_core of each node. You have to specify at least one of the resource variable or you can specify a valid available combination of the resources for a specific type of nodes. For some special nodes there are also the resources localscratch and linkspeed available.

Available node types:

node_type	node_type_cpu	node_type_mem	node_type_core	Graphic / Accelerator	localscratch	linkspeed	describes	notes	# of nodes (vulcan)	# of nodes (vulcan2)
clx-25	CascadeLake@2.50GHz	384gb	40c			HDR	cpu type intel XeonGold 6248 @ 2.5GHz, CascadeLake, 384GB memory	2 x 20 core-CPU per node	48	0
clx-21	CascadeLake@2.10GHz	384gb	40c		1.8TB /localscratch	HDR	cpu type intel XeonGold 6230 @ 2.5GHz, CascadeLake, 384GB memory, 1.8TB /localscratch	2 x 20 core-CPU per node	0	0
clx-ai	CascadeLake@2.60GHz	768gb	36c	8x Tesla V100 SXM2 32GB	7.3TB /localscratch, 220GB /tmp on SSD	HDR	cpu type intel XeonGold 6240 @ 2.6GHz, CascadeLake, 768GB memory, 7.3TB /localscratch, 220GB /tmp on SSD, 8x Tesla V100 SXM2 32GB	2 x 18 core-CPU + 8 GPU's per node	0	0
aurora	Skylake@2.60GHz	192gb	24c	8x NEC Aurora vector CPUs		EDR	cpu type intel XeonGold 6126 @ 2.6GHz, 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
hsw	Haswell@2.60GHz	128gb	20c			QDR	cpu type intel haswell, 128GB memory	2 x 10 core-CPU 2.6 ghz per node	84	0
hsw	Haswell@2.60GHz	256gb	20c			QDR	cpu type intel haswell, 256GB memory	2 x 10 core-CPU 2.6 ghz per node	4	0
hsw	Haswell@2.50GHz	128gb	24c			QDR	cpu type intel haswell, 128GB memory	2 x 12 core-CPU 2.5 ghz per node	152	192 (1 is in shared mode)
hsw	Haswell@2.50GHz	128gb	24c			FDR	cpu type intel haswell, 128GB memory	2 x 12 core-CPU 2.5 ghz per node	0	0
hsw	Haswell@2.50GHz	256gb	24c			QDR	cpu type intel haswell, 256GB memory	2 x 12 core-CPU 2.5 ghz per node	16	0
skl	Skylake@2.0GHz	192gb	40c			EDR	cpu type intel Xeon(R) Gold 6138 CPU @ 2.00GHz, 192GB memory	2 x 20 core-CPU 2.0 GHz per node	100	0
k20xm	IvyBridge@3.3Ghz	384gb	16c	Tesla K20Xm	11TB on SSD	QDR	node with intel IvyBridge@3.3Ghz, 16 cores, 384GB memory, 11TB local SSD scratch disk, Tesla K20Xm	only for single node jobs available	3	0
smp	Skylake@2.40GHz	1536gb	40c			FDR	cpu type intel Skylake, 1.5TByte memory,2 socket 20 core CPU's	will be shared with other jobs! Please use "qsub -q smp -l select=1:node_type=smp ..."	1 (shared)	0
visp100	Broadwell@3.20GHz	256gb	16c	Nvidia Tesla P100		FDR	Cuda Node with Nvidia Tesla P100, 8 core intel E5-2667v4 @ 3.2GHz, 256GB memory	only 1 node per job! Please use "qsub -q vis -l select=1:node_type=visp100 ..."	10	0
visnv	Skylake@2.60GHz	96gb	8c	Nvidia Quadro RTX 4000		HDR	Graphic Node with Nvidia Quadro RTX 4000, 8 core intel XeonSilver 4112 @ 2.6GHz, 96GB memory	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
visamd	Skylake@2.60GHz	96gb	8c	AMD Vega 10 Radeon PRO WX 8100/8200		HDR	Graphic Node with AMD Vega 10 Radeon PRO WX 8100/8200, 8 core intel XeonSilver 4112 @ 2.6GHz, 96GB memory	only 1 node per job! Please use "qsub -q vis -l select=1:node_type=visamd ..."	6	0
p100	Broadwell@3.00GHz	1024gb	24c	Nvidia Tesla P100	11TB on SSD	QDR	Cuda Node with Nvidia Tesla P100, 8 core intel E5-2687Wv4 @ 3.0GHz, 1024GB memory, 11TB local SSD scratch disk	reserved for special users! Please use "qsub -q R_i1 -l select=1:node_type=p100 ..."	3	0


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

select=1:node_type=hsw:node_type_mem=256gb+3:node_type=hsw:node_type_mem=128gb:node_type_core=20c

The example above will allocate 1 hsw node (a 20 core ore 24 core type) with 256 GB memory and 3 hsw nodes (the 20 cores type) with 128 GB memory.


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

select=1:node_type=il:localscratch=4TB

Or you want hsw nodes with network interconnect FDR, then you can use the special node resource variable linkspeed:

select=4:node_type=hsw:linkspeed=FDR

2. 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=hsw:mpiprocs=24
#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=hsw:mpiprocs=24 -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 48 MPI processes (mpiprocs=24 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 24 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 48 MPI processes with 24 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 -W sandbox=PRIVATE 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. PBSPro creates a job-specific directory in your home directory for the staging and execution during 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=hsw:ncpus=24:mpiprocs=24 -l walltime=00:30:00

If the requested resources are available and free (in the example above: 2 hsw nodes/24 cores each, 30 minutes, prepared for 24 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=sb ./myscript

The batch system allocates two node of type sb. 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:sb:mpiprocs=2+1:node_type=sb:mpiprocs=3 ./myscript

The batch system allocates 2 nodes of type sb each for 2 PE's and 1 node of type sb 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=hsw -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=hsw -l walltime=1:00 testjob.cmd

Following reservations are availalble at the moment:

reservation	resources	queue	limitations	notes
S1844	1 node of node_type sb	workday for routing to S1844	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 SandyBridge 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=sb: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:
  

  1. you have to specify a shell in the first line of your batch script
  2. you have to specify the number of nodes you need and the node type
  3. you have to specify the walltime the job needs
  4. 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 SandyBridge nodes
  #  and runs four MPI process on each node  (in total 8 MPI processes)
  # The walltime is 10min
  #
  #PBS -l select=2:node_type=sb: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 SandyBridge node using 2h
  #
  #PBS -l select=1:node_type=sb,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 'sb' and a real time of 2 hours:

  qsub -l select=3:node_type=sb,walltime=2:00:00 <script>



• Starting a script using 5 cluster nodes of node_type 'hsw' using 4 processors on each node:

  qsub -l select=5:node_type=hsw:mpiprocs=4,walltime=2:00:00 <script>



• Starting a script using 1 cluster node of type 'hsw' with 256GB memory and additional requesting 5 other 'hsw' nodes (24 cores) with 128GB memory and using 24 MPI processes on each of this 5 nodes; real job time is 1.5 hours:

  qsub -l select=1:node_type=hsw:node_type_mem=256gb+5:node_type=hsw:node_type_core=24c:node_type_mem=128gb:mpiprocs=24,walltime=1:30:00 <script>

  Warning: Because in the first chunk (1:node_type=hsw:node_type_mem=256gb) the number of cores for the node isn't specified, it's possible you will get a 20 core hsw node or a 24 core hsw node with 256 GB. The second chunk is clearly specified and you will get 5 hsw nodes each will have 128 GB and 20 cores.


• Starting a interactive batch job using 5 hsw nodes regardless how much memory or cores and with a job real time of 300 seconds:

  qsub -I -l select=5:node_type=hsw,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

  ssh <nodename>

  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 16 cores and 32 GB memory each regardless which type of nodes. And you want to run 16 MPI processes on each of the 4 nodes:

  qsub -l select=4:ncpus=16:mem=32g:mpiprocs=16 <script>

  Then its possible you will get a mix of 4 nodes composed of hsw or sb node types with different memory size or core size.

  Another possibilty to get explicit hsw nodes:

  qsub -l select=4:node_type=hsw:mem=256g:ncpus=20 <script>

  Because the qsub argument 'ncpus=20' requests nodes with at least 20 cores each, its possible you will get available hsw nodes with 20 cores or with 24 cores and with at least 256 GB memory.



• 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=sb,walltime=300 -W group_list=abc12345

Get the batch job status

Available commands

qstat [options]
nstat

For detailed informations, see man pages:

nstat -h
man qstat
man pbsnodes

Examples

list all batch jobs:

qstat -a

lists all batch queues with resource limit settings:

qstat -q

lists node information of a batch job ID:

qstat -n <JOB_ID>

lists detailed information of a batch job ID:

qstat -f <JOB_ID>

Displays estimated start time for queued jobs

qstat -T <JOB_ID>

Displays status information for 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

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




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