Hardware details

  • The cluster login nodes:
    • login.hpc.kuleuven.be and login2.hpc.kuleuven.be (use this hostname if you read vsc.login.node in the documentation and want to connect to this login node).
    • two GUI login nodes through NX server.
  • Compute nodes:
    • Thin node section:
      • 208 nodes with two 10-core "Ivy Bridge" Xeon E5-2680v2 CPUs (2.8 GHz, 25 MB level 3 cache). 176 of those nodes have 64 GB RAM while 32 are equiped with 128 GB RAM. The nodes are linked to a QDR Infiniband network. All nodes have a small local disk, mostly for swapping and the OS image.
      • 144 nodes with two 12-core "Haswell" Xeon E5-2680v3 CPUs (2.5 GHz, 30 MB level 3 cache). 48 of those nodes have with 64 GB RAM while 96 are equiped with 128 GB RAM. These nodes are linked to a FDR Infiniband network which offers lower latency and higher bandwidth than QDR.
      • 96 nodes with two 18-core "Skylake" Xeon 6140 CPUs(2.3GHz ). 86 nodes have 192GB RAM and 10 nodes are equiped with 768GB Ram.
    • SMP section (also known as Cerebro): a SGI UV2000 system with 64 sockets with a 10-core "Ivy Bridge" Xeon E5-4650 CPU (2.4 GHz, 25 MB level 3 cache), spread over 32 blades and connected through a SGI-proprietary NUMAlink6 interconnect. The interconnect also offers support for global address spaces across shared memory partitions and offload of some MPI functions. 16 sockets have 128 GB RAM and 48 sockets have 256 GB RAM, for a total RAM capacity of 14 TB. The peak compute performance is 12.3 Tflops in double precision arithmetic. The SMP system also contains a fast 21.8 GB disk storage system for swapping and temporary files. The system is partitioned in 2 shared memory partitions. 1 partition has 480 cores and 12 TB and 1 partition with 160 cores and 2TB. Both partitions have 10TB local scratch space.
      However, should the need arise it can be reconfigured into a single large 64-socket shared memory machine.More information can be found in the cerebro quick start guide or slides from the info-session.
    • Accelerator section:
      • 5 nodes with two 10-core "Haswell" Xeon E5-2650v3 2.3GHz CPUs, 64 GB of RAM and 2 GPUs Tesla K40 (2880 CUDA cores @ Boost clocks 810 MHz and 875 MHz, 1.66 DP Tflops/GPU Boost Clocks).
      • The central GPU and Xeon Phi system is also integrated in the cluster and available to other sites. Each node has two six-core Intel Xeon E5-2630 CPUs, 64 GB RAM and a local hard disk. All nodes are on a QDR Infiniband interconnect. This system consists of:
      • 8 nodes have two nVidia K20x cards each installed. Each K20x has 14 SMX processors (Kepler family; total of 2688 CUDA cores) that run at 732MHz and 6 GB of GDDR5 memory with a peak memory bandwidth of 250 GB/s (384-bit interface @ 2.6 GHz). The peak floating point performance per card is 1.31 Tflops in double and 3.95 Tflops in single precision.
      • 20 nodes have four Nvidia Tesla P100 SXM2 cards each installed (3584 CUDA cores @1328 MHz, 5.3 DP Tflops/GPU).
      • To start working with accelerators please refer to access webpage.
  • Visualization nodes: 2 nodes with two 10-core "Haswell" Xeon E5-2650v3 2.3GHz CPUs, 2 times 64 GB of RAM and 2 GPUs NVIDIA Quadro K5200 (2304 CUDA cores @ 667 MHz). To start working on visualization nodes, we refer to the TurboVNC start guide.
  • Central storage available to all nodes:
    • A NetApp NAS system with 70 TB of storage, used for the home- and permanent data directories. All data is mirrored almost instantaneously to the KU Leuven disaster recovery data centre.
    • A 1.2 PB GPFS parallel filesystem from DDN, mostly used for temporary disk space.
    • A 600 TB archive storage optimised for capacity and aimed at long-term storage of very infrequently accessed data. To start using the archive storage, we refer to the WOS Storage quick start guide.
  • For administrative purposes, there are also service nodes that are not user-accessible

Characteristics of the compute nodes

The following properties allow you to select the appropriate node type for your job (see also the page on specifying resources, output files and notifications):

Cluster Type of node CPU type Interconnect # cores installed mem avail mem local discs # nodes
Thinking ivybridge Xeon E5-2680v2 IB-QDR 20 64 GB 60 GB 250 GB 176
ThinKing ivybridge Xeon E5-2680v2 IB-QDR 20 128 GB 124 GB 250 GB 32
Thinking haswell Xeon E5-2680v3 IB-FDR 24 64 GB 60 GB 150 GB 48
Thinking haswell Xeon E5-2680v3 IB-FDR 24 128 GB 124 GB 150 GB 96
skylake Xeon 6140 IB-EDR 36 192 GB 188 GB 800 GB 86
Genius skylake-large memory Xeon 6140 IB-EDR 36 768 GB 764 GB 800 GB 10
Genius skylake-GPU Xeon 6140
4xP100 SXM2
IB-EDR 36 192 GB 188 GB 800 GB 20

For using Cerebro, the shared memory section, we refer to the Cerebro Quick Start Guide.
Genius was introduced at an infosession and the Genius Quickstart Guide

Implementation of the VSC directory structure

In the transition phase between Vic3 and ThinKing, the storage is mounted on both systems. When switching from Vic3 to ThinKing you will not need to migrate your data.

The cluster uses the directory structure that is implemented on most VSC clusters. This implies that each user has two personal directories:

  • A regular home directory which contains all files that a user might need to log on to the system, and small 'utility' scripts/programs/source code/.... The capacity that can be used is restricted by quota and this directory should not be used for I/O intensive programs.
    For KU Leuven systems the full path is of the form /user/leuven/... , but this might be different on other VSC systems. However, on all systems, the environment variable VSC_HOME points to this directory (just as the standard HOME variable does).
  • A data directory which can be used to store programs and their results. At the moment, there are no quota on this directory. For KU Leuven the path name is /data/leuven/... . On all VSC systems, the environment variable VSC_DATA points to this directory.

There are three further environment variables that point to other directories that can be used:

  • On each cluster you have access to a scratch directory that is shared by all nodes on the cluster. The variable VSC_SCRATCH_SITE will point to this directory. This directory is also accessible from the loginnodes, so it is accessible while your jobs run, and after they finish (for a limited time: files can be removed automatically after 14 days.)
  • Similarly, on each cluster you have a VSC_SCRATCH_NODE directory, which is a scratch space local to each computenode. Thus, on each node, this directory point to a different physical location, and the connects are only accessible from that particular worknode, and (typically) only during the runtime of your job. But, if more than one job of you runs on the same node, they all see the same directory (and thus you have to make sure they do not overwrite each others data by creating subdirectories per job, or give proper filename, ...)

Access restrictions

Access is available for faculty, students (under faculty supervision), and researchers of the KU Leuven, UHasselt and their associations. This cluster is being integrated in the VSC network and as such becomes available to all VSC users.


In September 2013 a new thin node cluster (HP) and a shared memory system (SGI) was bought. The thin node cluster was installed and configured in January/February 2014 and extended in september 2014. Installation and configuration of the SMP is done in April 2014. Financing of this systems was obtained from the Hercules foundation and the Flemish government.

Do you want to see it ? Have a look at the movie