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Terra:Batch Queues

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Upon job submission, Slurm sends your jobs to appropriate batch queues. These are (software) service stations configured to control the scheduling and dispatch of jobs that have arrived in them. Batch queues are characterized by all sorts of parameters. Some of the most important are:

  1. The total number of jobs that can be concurrently running (number of run slots)
  2. The wall-clock time limit per job
  3. The type and number of nodes it can dispatch jobs to

These settings control whether a job will remain idle in the queue or be dispatched quickly for execution.

The current queue structure is: (updated on January 29, 2020).

Queue Job Max Cores / Nodes Job Max Walltime Compute Node Types Per-User Limits Across Queues Notes
short 448 cores / 16 nodes 30 min / 2 hr 64 GB nodes (256) 1800 Cores per User
medium 1792 cores / 64 nodes 1 day
long 896 cores / 32 nodes 7 days 64 GB nodes (256)
xlong 448 cores / 16 nodes 21 days 64 GB nodes (256) 448 cores per User For jobs needing to run longer than 7 days.

Submit jobs to this partition with the --partition xlong option.

gpu 1344 cores / 48 nodes 3 days 128 GB nodes with GPUs (48) For jobs requiring a GPU or more than 64 GB of memory.
vnc 28 cores / 1 node 12 hours 128 GB nodes with GPUs (48) For jobs requiring remote visualization.
knl 68 cores / 8 nodes
72 cores / 8 nodes
7 days 96 GB nodes with KNL processors (8) For jobs requiring a KNL.

Checking queue usage

The following command can be used to get information on queues and their nodes.

[NetID@terra1 ~]$ sinfo

Example output:

short*           up     2:00:00      1-16        244/12/0/256     5333/1835/0/7168    

Note: A/I/O/T stands for Active, Idle, Offline, and Total

Checking node usage

The following command can be used to generate a list of nodes and their corresponding information, including their CPU usage.

[NetID@terra1 ~]$ pestat

Example output:

Hostname       Partition     Node Num_CPU  CPUload  Memsize  Freemem  Joblist
                          State Use/Tot              (MB)     (MB)  JobId User ...
knl-0101             knl   drain$   0  68    0.00*    88000        0   

Checking bad nodes

The following command can be used to view a current list of bad nodes on the machine:

[NetID@terra1 ~]$ bad_nodes.sh

The following output is just an example output and users should run bad_nodes.sh not see a current list.

Example output:

% bad_nodes.sh 
REASON                                                       USER             TIMESTAMP            STATE        NODELIST
The system board OCP1 PG voltage is outside of range.        root             2022-07-11T14:38:07  drained      fc152
FPGA preparation in progress                                 root             2022-07-12T15:57:01  drained*     fc[125-126]
investigating memverge license issue                         francis          2022-08-09T14:15:05  drained      fc032
investigating unknown memverge issue                         francis          2022-08-09T14:15:19  drained      fc033
fabric 1 hardware failure                                    francis          2022-08-15T13:52:10  drained*     fc[001-006,008,039-040]


Checkpointing is the practice of creating a save state of a job so that, if interrupted, it can begin again without starting completely over. This technique is especially important for long jobs on the batch systems, because each batch queue has a maximum walltime limit.

A checkpointed job file is particularly useful for the gpu queue, which is limited to 4 days walltime due to its demand. There are many cases of jobs that require the use of gpus and must run longer than two days, such as training a machine learning algorithm.

Users can change their code to implement save states so that their code may restart automatically when cut off by the wall time limit. There are many different ways to checkpoint a job file depending on the software used, but it is almost always done at the application level. It is up to the user how frequently save states are made depending on what kind of fault tolerance is needed for the job, but in the case of the batch system, the exact time of the 'fault' is known. It's just the walltime limit of the queue. In this case, only one checkpoint need be created, right before the limit is reached. Many different resources are available for checkpointing techniques. Some examples for common software are listed below.