HPC clusters installation
These instructions outline a few issues specific to high-performance computing (HPC) systems.
Most HPC clusters will run some flavour of GNU/Linux and hence a cluster administrator should be able to follow the steps outlined for a :ref:`linux_install`. In particular, if your sysadmin is able to install the required dependencies (the preferred option), you should be able to subsequently :ref:`linux_build`.
However, it is not uncommon for HPC systems to run stable, and hence relatively old distributions, with outdated dependencies. This is particularly problematic since MRtrix3 relies on recent technologies (C++11, OpenGL 3.3), which are only available on recent distributions. There is therefore a good chance these dependencies simply cannot be installed (certainly not without a huge amount of effort on the part of your sysadmin). In such cases, one can instead attempt a :ref:`linux_standalone`. Alternatively, if you (and your sysadmin) are comfortable with installation of dependencies from source within your home directory, you can try the instructions below.
Installation of MRtrix3 and dependencies from source
The following instructions list the steps I used to compile MRtrix3 natively on a local HPC cluster. Replicating these instructions line-for-line may not work on another system; I'm just providing these instructions here in case they help to point somebody in the right direction, or encourage users to try a native installation rather than resorting to transferring binaries compiled on another system.
Installing a C++11-compliant g++ from source
Note that during this process, there will be three
gccdirectories created: one is for the source code (including that of some prerequisites), one is for compilation objects, and one is the target of the final installation (since you almost certainly won't be able to install this version of
gccover the top of whatever is provided by the HPC sysadmin).
svn co svn://gcc.gnu.org/svn/gcc/branches/gcc-5-branch gcc_src/
(Don't checkout the trunk
gcccode; MRtrix3 will currently not compile with it)
gccdependencies will be built as part of the
gcccompilation, provided that they are placed in the correct location within the
wget https://gmplib.org/download/gmp/gmp-6.1.1.tar.bz2 tar -xf gmp-6.1.1.tar.bz2 mv gmp-6.1.1/ gcc_src/gmp/ wget ftp://ftp.gnu.org/gnu/mpc/mpc-1.0.3.tar.gz tar -xf mpc-1.0.3.tar.gz mv mpc-1.0.3/ gcc_src/mpc/ wget http://www.mpfr.org/mpfr-current/mpfr-3.1.4.tar.gz tar -xf mpfr-3.1.4.tar.gz mv mpfr-3.1.4/ gcc_src/mpfr/
With the following, the
configurescript (which resides within the
gcc_srcdirectory in this example) must not be executed within that directory; rather, it must be executed from an alternative directory, which will form the target location for the compilation object files. The target installation directory (set using the
--prefixoption below) must be a location for which you have write access; most likely somewhere in your home directory.
mkdir gcc_obj; cd gcc_obj/ ../gcc_src/configure --prefix=/path/to/installed/gcc --disable-multilib make && make install
Installing Python3 from source
My local HPC cluster provided Python version 2.6.6, which was not adequate to successfully run the
buildscripts in MRtrix3. Therefore this necessitated a manual Python install - a newer version of Python 2 would also work, but downloading Python 3 should result in less ambiguity about which version is being run.
wget https://www.python.org/ftp/python/3.5.2/Python-3.5.2.tgz tar -xf Python-3.5.2.tgz mv Python-3.5.2/ python3/ cd python3/ ./configure ./make cd ../
wget http://bitbucket.org/eigen/eigen/get/3.2.8.tar.gz tar -xf 3.2.8.tar.gz mv eigen* eigen3/
Personally I prefer to install a no-GUI version of MRtrix3 on high-performance computing systems, and transfer files to my local system if I need to view anything; so I use the
-noguiflag for the
git clone https://github.com/MRtrix3/mrtrix3.git cd mrtrix3/ export CXX=/path/to/installed/gcc/bin/g++ export EIGEN_CFLAGS="-isystem /path/to/eigen3/" export LD_LIBRARY_PATH="/path/to/installed/gcc/lib64:$LD_LIBRARY_PATH" ../python3/python configure -nogui ../python3/python build
If you encounter issues when running MRtrix3 commands that resemble the following:
mrconvert: /usr/lib64/libstdc++.so.6: version `GLIBCXX_3.4.9' not found (required by mrconvert)
This indicates that the shared library of the compiler version installed on the cluster is being found before that of the C++11-compliant compiler installed manually. The
lib64/directory of the manually-installed
gccversion must appear before that of the version installed on the cluster in the
Most people would expect to be able to run
mrview on the server using
X11 forwarding. Unfortunately, this will not work without some effort -
please refer to :ref:`remote_display` for details.
There are a number of parameters that can be set in the configuration
file that are highly relevant in a HPC environment, particularly when
the user's home folder is stored over a network-based filesystem (as is
often the case). The MRtrix3 configuration file is located either
/etc/mrtrix.conf, and/or in each user's home folder
~/.mrtrix.conf. Entries consist of
key: value entries, one
per line, stored as ASCII text.
- NumberOfThreads (default: hardware concurrency, as reported by the system): by default, MRtrix3 will use as many threads as the system reports being able to run concurrently. You may want to change that number to a lower value, to prevent MRtrix3 from taking over the system entirely. This is particularly true if you anticipate many users running many MRtrix3 commands concurrently.
- TmpFileDir (default: '/tmp'): any image data passed from one
MRtrix3 command to the next using a Unix pipeline is actually stored
in a temporary file, and its filename passed to the next command.
While this is fine if the filesystem holding the temporary file is
locally backed and large enough, it can cause significant slowdown
and bottlenecks if it resides on a networked filesystems, as the
temporary file will most likely need to be transferred in its
entirety over the network and back again. Also, if the filesystem is
too small, MRtrix3 commands may abort when processing large files. In
/tmpfolder is likely to be the most appropriate (especially if mounted as tmpfs). If however it is not locally mounted, or too small, you may want to set this folder to some other more suitable location.
- TrackWriterBufferSize (default: 16777216). When writing out track files, MRtrix3 will buffer up the output and write out in chunks of 16MB, to limit the frequency of write() calls and the amount of IO requests. More importantly, when several instances of MRtrix3 are generating tracks concurrently and writing to the same filesystem, frequent small writes will result in massive fragmentation of the output files. By setting a large buffer size, the chances of writes being concurrent is reduced drastically, and the output files are much less likely to be badly fragmented. Note that fragmentation can seriously affect the performance of subsequent commands that need to read affected data. Depending on the type of operations performed, it may be beneficial to use larger buffer sizes, for example 256MB. Note that larger numbers imply greater RAM usage to hold the data prior to write-out, so it is best to keep this much smaller than the total RAM capacity.