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* Both the standard Compute Canada software stack as well as cluster-specific software tuned for Niagara will be available.
* Both the standard Compute Canada software stack as well as cluster-specific software tuned for Niagara will be available.
* In contrast with Cedar and Graham, no modules will be loaded by default to prevent accidental conflicts in versions. There will be a simple mechanism to load the software stack that a user would see on Graham and Cedar.
* In contrast with Cedar and Graham, no modules will be loaded by default to prevent accidental conflicts in versions. There will be a simple mechanism to load the software stack that a user would see on Graham and Cedar.
= Migration to Niagara =
== Migration for Existing Users of the GPC ==
* Accounts, $HOME & $PROJECT of active GPC users transferred to Niagara (except dot-files in ~).
* Data stored in $SCRATCH will not be transfered automatically.
* Users are to clean up $SCRATCH on the GPC as much as possible (remember it's temporary data!). Then they can transfer what they need using datamover nodes. Let us know if you need help.
* To enable this transfer, there will be a short period during which you can have access to Niagara as well as to the GPC storage resources. This period will end no later than May 9, 2018.
== For Non-GPC Users ==
<ul>
<li><p>Those of you new to SciNet, but with 2018 RAC allocations on Niagara, will have your accounts created and ready for you to login.</p></li>
<li><p>New, non-RAC users: we are still working out the procedure to get access. If you can't wait, for now, you can follow the old route of requesting a SciNet Consortium Account on the [https://ccsb.computecanada.ca CCDB site].</p></li></ul>
=Using Niagara=
== Logging in ==
As with all SciNet and CC (Compute Canada) compute systems, access to Niagara is via ssh (secure shell) only.
To access SciNet systems, first open a terminal window (e.g. MobaXTerm on Windows).
Then ssh into the Niagara login nodes with your CC credentials:
<source lang="bash">
$ ssh -Y MYCCUSERNAME@niagara.scinet.utoronto.ca</source>
or
<source lang="bash">$ ssh -Y MYCCUSERNAME@niagara.computecanada.ca</source>
* The Niagara login nodes are where you develop, edit, compile, prepare and submit jobs.
* These login nodes are not part of the Niagara compute cluster, but have the same architecture, operating system, and software stack.
* The optional <code>-Y</code> is needed to open windows from the Niagara command-line onto your local X server.
* To run on Niagara's compute nodes, you must submit a batch job.
== Storage Systems and Locations ==
=== Home and scratch ===
You have a home and scratch directory on the system, whose locations will be given by
<code>$HOME=/home/g/groupname/myccusername</code>
<code>$SCRATCH=/scratch/g/groupname/myccusername</code>
<source lang="bash">nia-login07:~$ pwd
/home/s/scinet/rzon
nia-login07:~$ cd $SCRATCH
nia-login07:rzon$ pwd
/scratch/s/scinet/rzon</source>
=== Project location ===
Users from groups with a RAC allocation will also have a project directory.
<code>$PROJECT=/project/g/groupname/myccusername</code>
'''''IMPORTANT: Future-proof your scripts'''''
Use the environment variables (HOME, SCRATCH, PROJECT) instead of the actual paths!  The paths may change in the future.
=== Storage Limits on Niagara ===
{| class="wikitable"
! location
! quota
!align="right"| block size
! expiration time
! backed up
! on login
! on compute
|-
| $HOME
| 100 GB
|align="right"| 1 MB
|
| yes
| yes
| read-only
|-
| $SCRATCH
| 25 TB
|align="right"| 16 MB
| 2 months
| no
| yes
| yes
|-
| $PROJECT
| by group allocation
|align="right"| 16 MB
|
| yes
| yes
| yes
|-
| $ARCHIVE
| by group allocation
|align="right"|
|
| dual-copy
| no
| no
|-
| $BBUFFER
| ?
|align="right"| 1 MB
| very short
| no
| ?
| ?
|}
<ul>
<li>Compute nodes do not have local storage.</li>
<li>Archive space is on [https://wiki.scinet.utoronto.ca/wiki/index.php/HPSS HPSS].</li>
<li>Backup means a recent snapshot, not an achive of all data that ever was.</li>
<li><p><code>$BBUFFER</code> stands for the Burst Buffer, a functionality that is still being set up.  This will be a faster parallel storage tier for temporary data.</p></li></ul>
=== Moving data ===
'''''Move amounts less than 10GB through the login nodes.'''''
* Only Niagara login nodes visible from outside SciNet.
* Use scp or rsync to niagara.scinet.utoronto.ca or niagara.computecanada.ca (no difference).
* This will time out for amounts larger than about 10GB.
'''''Move amounts larger than 10GB through the datamover node.'''''
* From a Niagara login node, ssh to <code>nia-datamover1</code>.
* Transfers must originate from this datamover.
* The other side (e.g. your machine) must be reachable from the outside.
* If you do this often, consider using Globus, a web-based tool for data transfer.
'''''Moving data to HPSS/Archive/Nearline using the scheduler.'''''
* [https://wiki.scinet.utoronto.ca/wiki/index.php/HPSS HPSS] is a tape-based storage solution, and is SciNet's nearline a.k.a. archive facility.
* Storage space on HPSS is allocated through the annual [https://www.computecanada.ca/research-portal/accessing-resources/resource-allocation-competitions Compute Canada RAC allocation].
== Software and Libraries ==
=== Modules ===
Once you are on one of the login nodes, what software is already installed?
* Other than essentials, all installed software is made available using module commands.
* These set environment variables (<code>PATH</code>, etc.)
* Allows multiple, conflicting versions of a given package to be available.
* module spider shows the available software.
<source lang="bash">nia-login07:~$ module spider
---------------------------------------------------
The following is a list of the modules currently av
---------------------------------------------------
  CCEnv: CCEnv
  NiaEnv: NiaEnv/2018a
  anaconda2: anaconda2/5.1.0
  anaconda3: anaconda3/5.1.0
  autotools: autotools/2017
    autoconf, automake, and libtool
  boost: boost/1.66.0
  cfitsio: cfitsio/3.430
  cmake: cmake/3.10.2 cmake/3.10.3
  ...</source>
<ul>
<li><p><code>module load &lt;module-name&gt;</code></p>
<p>use particular software</p></li>
<li><p><code>module purge</code></p>
<p>remove currently loaded modules</p></li>
<li><p><code>module spider</code></p>
<p>(or <code>module spider &lt;module-name&gt;</code>)</p>
<p>list available software packages</p></li>
<li><p><code>module avail</code></p>
<p>list loadable software packages</p></li>
<li><p><code>module list</code></p>
<p>list loaded modules</p></li></ul>
On Niagara, there are really two software stacks:
<ol style="list-style-type: decimal;">
<li><p>A Niagara software stack tuned and compiled for this machine. This stack is available by default, but if not, can be reloaded with</p>
<source lang="bash">module load NiaEnv</source></li>
<li><p>The same software stack available on Compute Canada's General Purpose clusters [https://docs.computecanada.ca/wiki/Graham Graham] and [https://docs.computecanada.ca/wiki/Cedar Cedar], compiled (for now) for a previous generation of CPUs:</p>
<source lang="bash">module load CCEnv</source>
<p>If you want the same default modules loaded as on Cedar and Graham, then afterwards also <code>module load StdEnv</code>.</p></li></ol>
Note: the <code>*Env</code> modules are '''''sticky'''''; remove them by <code>--force</code>.
=== Tips for loading software ===
<ul>
<li><p>We advise '''''against''''' loading modules in your .bashrc.</p>
<p>This could lead to very confusing behaviour under certain circumstances.</p></li>
<li><p>Instead, load modules by hand when needed, or by sourcing a separate script.</p></li>
<li><p>Load run-specific modules inside your job submission script.</p></li>
<li><p>Short names give default versions; e.g. <code>intel</code> → <code>intel/2018.2</code>.</p>
<p>It is usually better to be explicit about the versions, for future reproducibility.</p></li>
<li><p>Handy abbreviations:</p></li></ul>
<pre class="sh">        ml → module list
        ml NAME → module load NAME  # if NAME is an existing module
        ml X → module X</pre>
* Modules sometimes require other modules to be loaded first.<br />
Solve these dependencies by using <code>module spider</code>.
=== Module spider ===
Oddly named, the module subcommand spider is the search-and-advice facility for modules.
<source lang="bash">nia-login07:~$ module load openmpi
Lmod has detected the error:  These module(s) exist but cannot be loaded as requested: "openmpi"
  Try: "module spider openmpi" to see how to load the module(s).</source>
<source lang="bash">nia-login07:~$ module spider openmpi
------------------------------------------------------------------------------------------------------
  openmpi:
------------------------------------------------------------------------------------------------------
    Versions:
        openmpi/2.1.3
        openmpi/3.0.1
        openmpi/3.1.0rc3
------------------------------------------------------------------------------------------------------
  For detailed information about a specific "openmpi" module (including how to load the modules) use
  the module s full name.
  For example:
    $ module spider openmpi/3.1.0rc3
------------------------------------------------------------------------------------------------------</source>
<source lang="bash">nia-login07:~$ module spider openmpi/3.1.0rc3
------------------------------------------------------------------------------------------------------
  openmpi: openmpi/3.1.0rc3
------------------------------------------------------------------------------------------------------
    You will need to load all module(s) on any one of the lines below before the "openmpi/3.1.0rc3"
    module is available to load.
      NiaEnv/2018a  gcc/7.3.0
      NiaEnv/2018a  intel/2018.2
</source>
<source lang="bash">nia-login07:~$ module load NiaEnv/2018a  intel/2018.2  # note: NiaEnv is usually already loaded
nia-login07:~$ module load openmpi/3.1.0rc3</source>
<source lang="bash">nia-login07:~$ module list
Currently Loaded Modules:
  1) NiaEnv/2018a (S)  2) intel/2018.2  3) openmpi/3.1.0.rc3
  Where:
  S:  Module is Sticky, requires --force to unload or purge</source>
== Can I Run Commercial Software? ==
* Possibly, but you have to bring your own license for it.
* SciNet and Compute Canada have an extremely large and broad user base of thousands of users, so we cannot provide licenses for everyone's favorite software.
* Thus, the only commercial software installed on Niagara is software that can benefit everyone: Compilers, math libraries and debuggers.
* That means no Matlab, Gaussian, IDL,
* Open source alternatives like Octave, Python, R are available.
* We are happy to help you to install commercial software for which you have a license.
* In some cases, if you have a license, you can use software in the Compute Canada stack.
== Compiling on Niagara: Example ==
<source lang="bash">nia-login07:~$ module list
Currently Loaded Modules:
  1) NiaEnv/2018a (S)
  Where:
  S:  Module is Sticky, requires --force to unload or purge
nia-login07:~$ module load intel/2018.2 gsl/2.4
nia-login07:~$ ls
main.c module.c
nia-login07:~$ icc -c -O3 -xHost -o main.o main.c
nia-login07:~$ icc -c -O3 -xHost -o module.o module.c
nia-login07:~$ icc  -o main module.o main.o -lgsl -mkl
nia-login07:~$ ./main</source>
== Testing ==
You really should test your code before you submit it to the cluster to know if your code is correct and what kind of resources you need.
<ul>
<li><p>Small test jobs can be run on the login nodes.</p>
<p>Rule of thumb: couple of minutes, taking at most about 1-2GB of memory, couple of cores.</p></li>
<li><p>You can run the the ddt debugger on the login nodes after <code>module load ddt</code>.</p></li>
<li><p>Short tests that do not fit on a login node, or for which you need a dedicated node, request an<br />
interactive debug job with the salloc command</p>
<source lang="bash">nia-login07:~$ salloc -pdebug --nodes N --time=1:00:00</source>
<p>where N  is the number of nodes. The duration of your interactive debug session can be at most one hour, can use at most 4 nodes, and each user can only have one such session at a time.</p></li></ul>
== Submitting jobs ==
<ul>
<li><p>Niagara uses SLURM as its job scheduler.</p></li>
<li><p>You submit jobs from a login node by passing a script to the sbatch command:</p>
<source lang="bash">nia-login07:~$ sbatch jobscript.sh</source></li>
<li><p>This puts the job in the queue. It will run on the compute nodes in due course.</p></li>
<li><p>Jobs will run under their group's RRG allocation, or, if the group has none, under a RAS allocation (previously called `default' allocation).</p></li></ul>
Keep in mind:
<ul>
<li><p>Scheduling is by node, so in multiples of 40-cores.</p></li>
<li><p>Maximum walltime is 24 hours.</p></li>
<li><p>Jobs must write to your scratch or project directory (home is read-only on compute nodes).</p></li>
<li><p>Compute nodes have no internet access.</p>
<p>Download data you need beforehand on a login node.</p></li></ul>
=== Example submission script (OpenMP) ===
<source lang="bash">#!/bin/bash
#SBATCH --nodes=1
#SBATCH --cpus-per-task=40
#SBATCH --time=1:00:00
#SBATCH --job-name openmp_job
#SBATCH --output=openmp_output_%j.txt
cd $SLURM_SUBMIT_DIR
module load intel/2018.2
export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
./openmp_example
# or "srun ./openmp_example".
</source>
<source lang="bash">nia-login07:~$ sbatch openmp_job.sh</source>
* First line indicates that this is a bash script.
* Lines starting with <code>#SBATCH</code> go to SLURM.
* sbatch reads these lines as a job request (which it gives the name <code>openmp_job</code>) .
* In this case, SLURM looks for one node with 40 cores to be run inside one task, for 1 hour.
* Once it found such a node, it runs the script:
** Change to the submission directory;
** Loads modules;
** Sets an environment variable;
** Runs the <code>openmp_example</code> application.
=== Example submission script (MPI) ===
<source lang="bash">#!/bin/bash
#SBATCH --nodes=8
#SBATCH --ntasks=320
#SBATCH --time=1:00:00
#SBATCH --job-name mpi_job
#SBATCH --output=mpi_output_%j.txt
cd $SLURM_SUBMIT_DIR
module load intel/2018.2
module load openmpi/3.1.0rc3
mpirun ./mpi_example
# or "srun ./mpi_example"
</source>
<source lang="bash">nia-login07:~$ sbatch mpi_job.sh</source>
<ul>
<li><p>First line indicates that this is a bash script.</p></li>
<li><p>Lines starting with <code>#SBATCH</code> go to SLURM.</p></li>
<li><p>sbatch reads these lines as a job request (which it gives the name <code>mpi_job</code>)</p></li>
<li><p>In this case, SLURM looks for 8 nodes with 40 cores on which to run 320 tasks, for 1 hour.</p></li>
<li><p>Once it found such a node, it runs the script:</p>
<ul>
<li>Change to the submission directory;</li>
<li>Loads modules;</li>
<li>Runs the <code>mpi_example</code> application.</li></ul>
<p></p></li></ul>
== Monitoring queued jobs ==
Once the job is incorporated into the queue, there are some command you can use to monitor its progress.
<ul>
<li><p><code>squeue</code> to show the job queue (<code>squeue -u $USER</code> for just your jobs);</p></li>
<li><p><code>squeue -j JOBID</code> to get information on a specific job</p>
<p>(alternatively, <code>scontrol show job JOBID</code>, which is more verbose).</p></li>
<li><p><code>squeue -j JOBID -o &quot;%.9i %.9P %.8j %.8u %.2t %.10M %.6D %S&quot;</code> to get an estimate for when a job will run.</p></li>
<li><p><code>scancel -i JOBID</code> to cancel the job.</p></li>
<li><p><code>sinfo -pcompute</code> to look at available nodes.</p></li>
<li><p>More utilities like those that were available on the GPC are under development.</p></li></ul>
== Data Management and I/O Tips ==
* $HOME, $SCRATCH, and $PROJECT all use the parallel file system called GPFS.
* Your files can be seen on all Niagara login and compute nodes.
* GPFS is a high-performance file system which provides rapid reads and writes to large data sets in parallel from many nodes.
* But accessing data sets which consist of many, small files leads to poor performance.
* Avoid reading and writing lots of small amounts of data to disk.<br />
* Many small files on the system would waste space and would be slower to access, read and write.
* Write data out in binary. Faster and takes less space.
* Burst buffer (to come) is better for i/o heavy jobs and to speed up checkpoints.


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