1. Introduction

This document provides a brief summary of information you'll need to quickly begin working on Narwhal. For more detailed information, see the Narwhal User Guide.

2. Get a Kerberos Ticket

For security purposes, you must have a current Kerberos ticket on your computer before attempting to connect to Narwhal. A Kerberos client kit must be installed on your desktop to get a Kerberos ticket. Information about installing Kerberos clients on your Windows desktop can be found on the Kerberos & Authentication page.

3. Connect to Narwhal

Narwhal can be accessed via Kerberized ssh as follows:

% ssh user@narwhal.navydsrc.hpc.mil

4. Home, Working, and Center-wide Directories

Each user has file space in the $HOME, $WORKDIR, and $CENTER directories. The $HOME, $WORKDIR, and $CENTER environment variables are predefined for you and point to the appropriate locations in the file systems. You are strongly encouraged to use these variables in your scripts.

Note: $WORKDIR is a "scratch" file system, and $CENTER is a center-wide file system accessible to all Navy DSRC production systems. Neither of these file systems is backed up. You are responsible for managing files in your $WORKDIR and $CENTER directories by backing up files to the archive system and deleting unneeded files. Currently, $WORKDIR files older than 14 days and $CENTER files older than 180 days are subject to being purged.

If it is determined as part of the normal purge cycle that files in your $WORKDIR directory must be deleted, you WILL NOT be notified prior to deletion. You are responsible to monitor your workspace to prevent data loss.

5. Transfer Files and Data to Narwhal

File transfers to DSRC systems must be performed using Kerberized versions of the following tools: scp, sftp, and mpscp. For example, the command below uses secure copy (scp) to copy a local file into a destination directory on a Narwhal login node.

% scp local_file user@narwhal.navydsrc.hpc.mil:/target_dir

For additional information on file transfers to and from Narwhal, see the File Transfers section of the Narwhal User Guide.

6. Submit Jobs to the Batch Queue

The Portable Batch System (PBS) is the workload management system for Narwhal. To submit a batch job, use the following command:

qsub [ options ] my_job_script

where my_job_script is the name of the file containing your batch script. For more information on using PBS or job scripts, see the Narwhal User Guide, the Narwhal PBS Guide, or the sample script examples in the $SAMPLES_HOME directory on Narwhal.

7. Batch Queues

The following table describes the PBS queues available on Narwhal:

8. Monitoring Your Job

You can monitor your batch jobs on Narwhal using the qpeek, qview, or qstat commands.

The qstat command lists all jobs in the queue. The -u username option shows only jobs owned by the given user, as follows:

% qstat -u user1
                                                           Req'd  Req'd    Elap
Job ID           Username Queue     Jobname SessID NDS TSK Memory Time  S  Time
--------         -------- --------  ------- ------ --- --- ------ ----- -  -----
815.narwhal-pbs1  user1   debug     mytest  1766   1   128   --   00:30 R  00:12
824.narwhal-pbs1  user1   frontier  inspect --     8   1024  --   06:00 Q   --
825.narwhal-pbs1  user1   standard  45dh8   2584   10  128   --   02:00 R  14:22

Notice that the output contains the JobID for each job. This ID can be used with the qpeek, qview, qstat, and qdel commands.

To delete a job, use the command qdel jobID.

To view a partially completed output file, use the qpeek jobID command.

9. Archiving Your Work

When your job is finished, you should archive any important data to prevent automatic deletion by the purge scripts.

Copy one or more files to the archive system.
archive put [-C path ] [-D] [-s] file1 [file2 ...]

Copy one or more files from the archive system.
archive get [-C path ] [-s] file1 [file2 ...]

For more information on archiving your files, see the Navy DSRC Archive Guide.

10. Modules

Software modules are a very convenient way to set needed environment variables and include necessary directories in your path so commands for particular applications can be found. Narwhal uses modules to initialize your environment with COTS application software, system commands and libraries, compiler suites, environment variables, and PBS batch system commands.

Several modules are loaded automatically as soon as you log in. To view the currently loaded modules, use module list. To see the entire list of available modules, use module avail. You can modify the configuration of your environment by loading and unloading modules. For complete information on how to do this, see the Navy DSRC Modules Guide.

11. Available Software

A list of software on Narwhal is available on the Software page.

12. Advance Reservation Service (ARS)

A subset of Narwhal's nodes has been set aside for use as part of the ARS. The ARS allows users to reserve a user-designated number of nodes for a specified number of hours starting at a specific date/time. This service enables users to execute interactive or other time-critical jobs within the batch system environment. The ARS is accessible at https://reservation.hpc.mil. Authenticated access is required. For more information on ARS, see the ARS User Guide.