# Slurm User Group Meeting 2014

Hosted by the Swiss National Supercomputing Centre

# Agenda

The 2014 Slurm User Group Meeting will be held on September 23 and 24 in Lugano, Switzerland. The meeting will include an assortment of tutorials, technical presentations, and site reports. The Schedule amd Abstracts are shown below.

The meeting will be held at the Convention Centre Lugano, Lugano, Switzerland.

# Registration

The conference cost is $350 per person for registration by 23 August and $400 per person for late registration. This includes presentations, tutorials, lunch and snacks on both days, plus dinner on Tuesday evening.
Register here.

# Hotel Information

Hotels may be booked through the Lugano Convention Centre (Palazzo dei Congressi).
Hotel booking.

# Schedule

## 23 September 2014

Time | Theme | Speaker | Title
--- | --- | --- | ---
08:00 - 08:30 | Registration
08:30 - 08:40 | Welcome | Colin McMurtrie (CSCS) | Welcome to Slurm User Group Meeting
08:40 - 09:30 | Keynote | Prof. Felix Schürmann (EPFL) | European Human Brain Project
09:30 - 09:45 | Break
09:45 - 10:15 | Technical | Morris Jette (SchedMD), Yiannis Georgiou (Bull) | Overview of Slurm Versions 14.03 and 14.11
10:15 - 10:45 | Tutorial | Michael Jennings, Jacqueline Scoggins (LBL) | Warewulf Node Health Check
| 10:45 - 11:15 | Technical | Yiannis Georgiou (BULL), David Glesser (BULL), Matthieu Hautreux (CEA), Denis Trystram (Univ. Grenoble-Alpes) | SLURM processes isolation
11:15 - 11:45 | Technical | Rod Schultz (BULL), Martin Perry (BULL), Yiannis Georgiou (BULL), Danny Auble (SchedMD), Morris Jette (SchedMD), Matthieu Hautreux (CEA) | Improving forwarding logic in SLURM
| 11:45 - 12:45 | Lunch 12:45 - 13:45 | Tutorial | Morris Jette (SchedMD) | Tuning Slurm Scheduling for Optimal Responsiveness and Utilization
13:45 - 14:15 | Technical | Carles Fenoy (BSC) | Improving HPC applications scheduling with predictions based on automatically-collected historical data
14:15 - 14:45 | Technical | Filip Skalski, Krzysztof Rzadca (University of Warsaw) | Fair Scheduler for Burst Submissions of Parallel Job
14:45 - 15:00 | Break
15:00 - 15:30 | Technical | Yiannis Georgiou (BULL), David Glesser (BULL), Matthieu Hautreux (CEA), Denis Trystram (Univ. Grenoble-Alpes) | Introducing Power-capping in SLURM scheduling
15:30 - 16:00 | Technical | David Glesser (BULL), Yiannis Georgiou (BULL), Denis Trystram (Univ. Grenoble-Alpes) | Introducing Energy based fair-share scheduling
16:00 - 16:30 | Technical | Aamir Rashid (Terascala) | Data movement between Lustre and Enterprise storage systems
16:30 - 17:00 | Technical | Sergio Iserte, Adrian Castello, Rafael Mayo, Enrique S. Quintana-Ort (Universitat Jaume I de Castello), Federico Silla, Jose Duato (Universitat Politecnica de Valencia) | Extending SLURM with Support for Remote GPU Virtualization
19:00 - | Dinner | Restaurant Pizzeria Cantinone Piazza Cioccaro 8 Lugano tel +41(0)91 923 10 68

## 24 September 2014

Time | Theme | Speaker | Title
--- | --- | --- | ---
08:00 - 08:30 | Registration
08:30 - 09:00 | Technical | Jacqueline Scoggins (Lawrence Berkeley National Lab) | Complex environment migration from Moab/Torque to Slurm
09:00 - 09:30 | Technical | Huub Stoffers (SURFsara) | A budget checking / budget tracking plug-in for SLURM
09:30 - 10:00 | Technical | Ryan Cox, Levi Morrison (Brigham Young University) | Level-based job prioritization
10:00 - 10:15 | Break
10:15 - 10:45 | Technical | Thomas Cadeau (BULL), Yiannis Georgiou (BULL), Matthieu Hautreux (CEA) | Integrating Layouts Framework in SLURM
10:45 - 11:15 | Technical | Emmanuel Jeannot, Guillaume Mercier, Adèle Villiermet (INRIA) | Topology-aware Resource Selection with Slurm
11:15 - 11:45 | Technical | Stephen Trofinoff (CSCS) | Exploring the implementation of several key Slurm Inter-cluster features
11:45 - 12:15 | Technical | Danny Auble (SchedMD) | Slurm Native Workload Management on Cray Systems
12:15 - 13:15 | Lunch
13:15 - 13:45 | Technical | Morris Jette (SchedMD), Yiannis Georgiou (Bull) | Slurm Roadmap
13:45 - 14:05 | Site Report | Magnus Jonsson (Umea University) | Umea University Site Report
14:05 - 14:25 | Site Report | Marcin Stolarek and Dominik Bartkiewicz (Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), University of Warsaw, Poland) | University of Warsaw Site Report
14:25 - 14:45 | Site Report | Andrew Elwell (iVEC) | iVEC Site Report
14:45 - 15:05 | Site Report | Matthieu Hautreux (CEA) | CEA Site Report
15:05 - 15:20 | Break
15:20 - 15:40 | Site Report | Benini Massimo (CSCS) | CSCS Site Report
15:40 - 16:00 | Site Report | Janne Blomqvist, Ivan Degtyarenko, Mikko Hakala (Aalto University) | Aalto University Site Report
16:00 - 16:20 | Site Report | Tim Wickberg (George Washington University) | George Washington University Site Report
16:20 - 16:30 | Closing | Tim Wickberg (George Washington University), Morris Jette (SchedMD) | Closing/Invitation to Slurm User Group Meeting 2015

# Abstracts

## September 23, 2014

### Keynote

Prof. Felix Schürmann (Ecole Polytechnique Fédérale de Lausanne)

Dr. Felix Schürmann is adjunct professor at the Ecole Polytechnique Fédérale de Lausanne, co-director of the Blue Brain Project and involved in several research challenges of the European Human Brain Project.

### Overview of Slurm Versions 14.03 and 14.11

Morris Jette (SchedMD), Yiannis Georgiou (Bull)

This presentation will describe new capabilities provided in Slurm versions 14.03 (released March 2014) and planned for version 14.11 (to be released in November 2014). Major enhancements in version 14.03 include:

- Access control options for partitions
- Load-based scheduling
- Reservation of cores for system use
- Native support for Cray systems

Major enhancements planned for version 14.11 include:

- Support for heterogeneous generic resources
- Support for non-consumable generic resources
- Automatic job requeue based upon exit code
- User control over CPU governor
- Communication gateways
- New options for job scheduling and task layout
- Improved job array support

### Warewulf Node Health Check

Michael Jennings, Jacqueline Scoggins (Lawrence Berkeley National Lab)

Since its release to the HPC community in 2011, the Warewulf Node Health Check system has gained wide acceptance across the industry and has become the de facto standard community solution for compute node health checking. It provides a complete, optimized framework for creating and executing node-level checks and already comes with more than 40 of its own pre-written checks. It fully supports SLURM (as well as other popular schedulers & resource managers) and can directly error/drain failed nodes and subsequently return them to service once fixed. Having been used in production at Lawrence Berkeley National Laboratory since late-2010, Warewulf NHC has evolved and matured to become a vital asset in maximizing the integrity and reliability of high-performance computational resources.

In this talk, we'll discuss what makes Warewulf NHC such a unique and robust solution to the problem of compute node health, look at the feature set of NHC and its integration with SLURM, examine LBNL's configuration and utilization of SLURM and NHC with tips on how to quickly deploy it in your environment, and survey many of the available checks that are supplied out-of-the-box. Time permitting, a brief introduction to writing custom or site-specific checks may also be included.

### SLURM processes isolation

Martin Perry (BULL), Bill Brophy (BULL), Yiannis Georgiou (BULL), Danny Auble (SchedMD), Morris Jette (SchedMD), Matthieu Hautreux (CEA)

On the compute nodes Slurm related processes and threads share the resources (CPUs, Memory) with the applications. Even if the overhead of slurm processes and threads is not really important, there could be interference and de-synchronization in cases where the application makes heavy usage of resources.

The goal is to automatically confine the slurm related process and threads (slurmd, slurmstepd, jobacct, etc) on particular cores and memory of the compute node. This will limit the interference of slurm on the application execution and may improve the performance of the applications. We present the design choices along with the developed code and we provide experiments and observations.

### Improving forwarding logic in SLURM

Rod Schultz (BULL), Martin Perry (BULL), Yiannis Georgiou (BULL), Danny Auble (SchedMD), Morris Jette (SchedMD), Matthieu Hautreux (CEA)

In this presentation we describe the motivations and design of the communication logic re-factoring in Slurm in order to provide partially deterministic direct and reverse tree communications. The goals of these developments are to:

- Better handle the mapping between the trees of communication used by SLURM and the existing physical network connections in order to improve performance.
- Provide the ability to aggregate messages directed to the controller in order to limit the amount of RPC that have to be managed simultaneously so that we can diminish communication bottlenecks.

### Tuning Slurm Scheduling for Optimal Responsiveness and Utilization

Morris Jette (SchedMD)

Slurm supports a multitude of scheduling options to achieve administrative goals for responsiveness, utilization, and service level under a wide assortment of workloads. Many of these options have been added in the past year and are still little known. This tutorial will present an overview of scheduling configuration options for job prioritiziation, Quality of Service, backfill scheduling, job preemption, and gang scheduling. Advice will be provided on how to analyze current workload and tune the system.

### Improving HPC applications scheduling with predictions based on automatically-collected historical data

Carles Fenoy (BSC)

This work analyses the benefits of a system, which being able to get real performance data from jobs, uses it for future scheduling in order to improve the performance of the applications with minimal user input. The study is focused on the memory bandwidth usage of applications and its impact on the running time when sharing the same node with other jobs. The data used for scheduling purposes is extracted from the hardware counters during the application execution identified by a tag specified by e user. This information allows the system to predict the resource requirements of a job and allocate it more effectively.

### Fair Scheduler for Burst Submissions of Parallel Job

Filip Skalski, Krzysztof Rzadca (Institute of Informatics, University of Warsaw, Poland)

Large-scale HPC systems are shared by many users. Beside system's efficiency, the main goal of the scheduler is to serve users according to a scheduling policy. The fair-share algorithm strives to build schedules in which each user achieves her target average utilization rate. This method was fine when each user had just a few jobs. However, modern workloads are often composed of campaigns: many jobs submitted by the same user at roughly the same time (e.g. bag-of-tasks or SLURM's job arrays). For such workloads, fair-share is not optimal because users frequently have similar utilization metrics and, in such situations, the schedule switches between users, executing just a few jobs of each one of them. However, it would be more efficient to assign the maximum number of resources to one user per time.

OStrich, our scheduling algorithm, is optimized for campaigns of jobs. OStrich maintains a virtual schedule that partitions resources between users' workloads according to pre-defined shares. The virtual schedule drives the allocation of the real processors.

We implemented OStrich as a priority plugin for SLURM and performed experimental evaluation on an emulated cluster. Comparing with fair-share (the multifactor plugin), OStrich schedules have lower slowdowns while maintaining equal system utilization. Moreover, OStrich plugin uses normalized shares similarly to the multifactor plugin, therefore it doesn't require any administrative changes other than a simple change to the SLURM configuration file. We think that OStrich is a viable alternative to fair-share in supercomputers with campaign-like workloads.

### Introducing Power-capping in SLURM scheduling

Yiannis Georgiou (BULL), David Glesser (BULL), Matthieu Hautreux (CEA), Denis Trystram (Univ. Grenoble-Alpes)

The last decades have been characterized by an ever growing requirement in terms of computing and storage resources. This tendency has recently put the pressure on the ability to efficiently manage the power required to operate the huge amount of electrical components associated with state-of-the-art computing and data centers. The power consumption of a supercomputer needs to be adjusted based on varying power budget or electricity availabilities. As a consequence, Resource and Job Management Systems have to be adequately adapted in order to efficiently schedule jobs with optimized performance while limiting power usage whenever needed. Our goal is to introduce a new power consumption adaptive scheduling strategy that provides the capability to autonomously adapt the executed workload to the available or planned power budget. The originality of this approach relies on a combination of DVFS (Dynamic Voltage and Frequency Scaling) and node shut-down techniques.

### Introducing Energy based fair-share scheduling

David Glesser (BULL), Yiannis Georgiou (BULL), Denis Trystram (Univ. Grenoble-Alpes)

Energy consumption has become one of the most important parameters in High Performance computing platforms. Fair-share scheduling is a widely used technique in job schedulers to prioritize jobs, depending to past users allocations. In practice this technique is mainly based on CPU-Time usage. Since power is managed as a new type of resources by SLURM and energy consumption can be charged independently, there is a real need for fairness in terms of energy consumption.

This presentation will introduce fair-share scheduling based on past energy usage in SLURM. The new technique will allow users that have optimized their codes to be more energy efficient or make better usage of DVFS techniques to improve the stretch times of their workload.

### Data movement between Lustre and Enterprise storage systems

Aamir Rashid (Terascala)

High Performance Data movement is a requirement and a challenge for HPC (large data sets, high rate of processing, over-provisioning, compliance, etc.). An example is the data movement inherent in HPC workflows like genome sequencing. This problem belongs to application users and is related to HSM. If users are able to effectively manage data movement tasks as part of their workflows then the IT storage management problem is significantly diminished. However, to accomplish this, users need tools that they currently do not have.

Terascala has developed a new product, Intelligent Storage Bridge (ISB), for effective data movement between a Lustre appliance and Enterprise storage systems. ISB is a highly available, scalable and a policy driven engine that is geared towards end users and automated workflows. This talk will discuss the features of SLURM that are most important in a user driven data management solution and highlight lessons learned.

### Extending SLURM with Support for Remote GPU Virtualization

Sergio Iserte, Adrian Castello, Rafael Mayo, Enrique S. Quintana-Ort (Universitat Jaume I de Castello) Federico Silla, Jose Duato (Universitat Politecnica de Valencia)

Remote GPU virtualization offers an alluring means to increase utilization of the GPUs installed in a cluster, which can potentially yield a faster amortization of the total costs of ownership (TCO). Concretely, GPU virtualization logically decouples the GPUs in the cluster from the nodes they are located in, opening a path to share the accelerators among all the applications that request GPGPU services, independently of whether the node(s) these applications are mapped to are equipped with a GPU or not. In this manner the amount of these accelerators can be reduced, and their utilization rate can be significantly improved.

SLURM can use a generic resource plug-in (GRes) to manage GPUs. With this solution the hardware accelerators, like the GPUs, can only be accessed by the job that is in execution on the node to which the GPU is attached. This is a serious constraint for remote GPU virtualization technologies, which aim to provide a completely user-transparent access to all GPUs in cluster, independently of the specific locations of the application node and the GPU node.

In this work we introduce a new type of resource in SLURM, the remote GPU (rGPU), in order to gain access from any application node to any GPU node in the cluster using rCUDA as the remote GPU virtualization solution. With this new resource, users can access all GPUs needed for their jobs, as SLURM schedules the task taking into account all the GPUs available in the whole cluster. In other words, introducing GPU-virtualization aware mechanism into SLURM allow applications to execute CUDA kernels in all GPUs, independently of their location.

## September 24, 2014

### Complex environment migration from Moab/Torque to Slurm

Jacqueline Scoggins (Lawrence Berkeley National Lab)

In most HPC environments admins are faced with setting up a scheduling environment based on the individual or institutional cluster requirements. Sites that have multiple clusters may have to install the same scheduler on each system but the policies and functionality might be different between the various installations. But as the number of clusters grow and the policies and requirements change this can become very difficult to manage. How can this be done simpler without the integration nightmares? At LBNL we merged our distinct resources under a common infrastructure to leverage a uniform support architecture and scavenge unused CPU cycles and expand into a condo-cluster model using one scheduler. We previously did this using Moab/Torque for several years but recently migrated to SLURM. The challenge was how to make SLURM meet the exceedingly arduous needs of our environment – Accounting, backfill, reservations, fairshare, QOS, Partitions, Multifactor job prioritization and the ability to have limits set on a user/group level bases so that the individual and institutional clusters would not affect each other. Considering our extremely complicated environment and the many production resources and users that were impacted by this change, we took a very careful and diligent approach to the migration and it resulted with minimal adverse effects on our user base and support engineers. This talk will be focused on our method and experiences of this migration.

### A budget checking / budget tracking plug-in for SLURM

Huub Stoffers (SURFsara)

We propose to design and implement a plug-in for the SLURM control daemon that is capable of calculating “job cost” on the basis of job resource usage and that keeps track of budgets, registered per account, as they are spent by running jobs. SLURM does a good job logging the run time of jobs and their usage of resources during that time interval. It however does not know how to reduce the usage of resources to the spending of budget that was granted to projects.

Traditionally, this is not the responsibility of the batch system but of the site's accounting system, because the decision which resource(s) to account, and at what price, are very site specific. Moreover, translating the resource usage of a job to budget reductions is most conveniently done after job completion, when the resource usage is final and completely known. Then, the "raw" data can simply be handed over to the accounting system for subsequent interpretation. But this division of labor and its associated sequence of events have a serious disadvantage: Overspending by projects is only noticed when it has already happened.

Projects running on our compute facilities generally can do so because they have successfully passed through a review process and were granted a budget to be spent on compute resources on behalf of the project. Sometimes it is possible to get a prolongation for a project or to shift an amount of budget between two projects granted to the same primary investigator. But funding agencies are quite strict. They do not wish to tolerate that any project spends more budget then it was formally granted.

New jobs likely to cost more than their project’s remaining budgets simply should not be dispatched. SLURM already has the concept that a job is run under an account that is associated with one or more users. A budget should be associated with such an account too. “Job cost” is presumably highly dependent on the actual run time of the job. When a job is about to be dispatched, its maximum “job cost” must be calculated, based on its attributes, such as number of cores or nodes, the partition, its maximum wall clock time. The maximum job cost must be temporarily claimed, subtracted from the project’s budget, for as long as the job runs. When the job is finished the actual job cost can be calculated, permanently subtracted from the budget while at the same time, the temporarily claimed maximum “job cost” is given back – i.e. added again.

Preventive, “live”, budget checking during each job dispatch presently can be implemented, or at least approximated, by a prologue script. But this involves substantial sacct and squeue querying and subsequent calculations based on the returned results that can strain the system much more that directly keeping track of a project’s budget. Budgets are typically specified in terms of abstract "system billable units" that can be spent by using, discrete quantities the resources that the compute facility has to offer. The number of core hours is usually an important resource that is accounted, but there may be differences in pricing, e.g. between the core hours on nodes with or without GPU support, or with lesser or larger quantities of memory per core. Other consumable resources, such as the time that particular software licenses are checked out by a job, may be accounted too. In SLURM it is customary to use partitions to differentiate between heterogeneously equipped nodes. Clearly, the relative pricing of core hours of different partitions should be a configurable in the configuration file of the plug-in. The actual details of “Job cost” calculation will remain site specific and hence should be concentrated in a single jobcost function. Hooks should be added for it to be called and process its outcome at job dispatch time and – for a job that is dispatched – at job completion time.

### Level-based job prioritization

Ryan Cox and Levi Morrison (Brigham Young University)

We will present about our new LEVEL_BASED job prioritization mechanism. The algorithm prioritizes users such that users in an under-served account will always have a higher fair share factor than users in an over-served account. It recurses through the account tree, calculates fair share at each level, then uses bitwise math to ensure that the effect of usage and shares below the current level cannot affect calculations at the current level.

Basically, if accounts A and B have the same shares but A has higher usage than B then children of account A will have a lower fair share factor than children of account B. This is not guaranteed in other prioritization methods. LEVEL_BASED was also designed to reduce the likelihood of errors due to floating point precision loss.

### Integrating Layouts Framework in SLURM

Thomas Cadeau (BULL), Yiannis Georgiou (BULL), Matthieu Hautreux (CEA)

Supercomputers become more powerful but more complicated to manage. Resources hide information that can be taken into account for more efficient management. Those characteristics may impact the way resources should be used and may provide valuable information ( such as power consumption, network details, etc) that can be used to optimize automatic decisions such as Scheduling, Energy Efficiency, Placement, Scalability.

The layouts framework has been introduced in the last SLURM User Group. This presentation will introduce a new API that has been developed to get, update and consolidate information described by layouts so that they can be used wherever needed internally in SLURM. Information such as the placement of each resource in the actual infrastructure can be taken into account for more efficient scheduling of jobs. Information such as the power consumption of resources can be taken into account for power aware scheduling.

Furthermore a new set of scontrol options will be presented to enable users and administrators to dynamically modify and display layouts information.

### Topology-aware Resource Selection with Slurm

Emmanuel Jeannot, Guillaume Mercier, Adèle Villiermet (INRIA)

Remote GPU virtualization offers an alluring means to increase utilization of the GPUs installed in a cluster, which can potentially yield a faster amortization of the total costs of ownership (TCO). Concretely, GPU virtualization logically decouples the GPUs in the cluster from the nodes they are located in, opening a path to share the accelerators among all the applications that request GPGPU services, independently of whether the node(s) these applications are mapped to are equipped with a GPU or not. In this manner the amount of these accelerators can be reduced, and their utilization rate can be significantly improved.

SLURM can use a generic resource plug-in (GRes) to manage GPUs. With this solution the hardware accelerators, like the GPUs, can only be accessed by the job that is in execution on the node to which the GPU is attached. This is a serious constraint for remote GPU virtualization technologies, which aim to provide a completely user-transparent access to all GPUs in cluster, independently of the specific locations of the application node and the GPU node.

In this work we introduce a new type of resource in SLURM, the remote GPU (rGPU), in order to gain access from any application node to any GPU node in the cluster using rCUDA as the remote GPU virtualization solution. With this new resource, users can access all GPUs needed for their jobs, as SLURM schedules the task taking into account all the GPUs available in the whole cluster. In other words, introducing GPU-virtualization aware mechanism into SLURM allow applications to execute CUDA kernels in all GPUs, independently of their location.

### Exploring the implementation of several key Slurm Inter-cluster features

Stephen Trofinoff (CSCS)

Over the course of several years, both at our site (CSCS) and at others of which we were told, various instances have arisen where there was a need for some inter-cluster Slurm features. These features would simplify or in some cases enable use cases for our various computing facilities and potentially make administering them easier. One prominent such request, was for the ability to chain a job to one or more jobs on a remote Slurm cluster. These features, of course, do not currently exist or are limited in their scope. For instance, a job can be submitted to a remote Slurm cluster but can not be "chained" to a job on another cluster since one Slurm cluster's controller has no knowledge of the jobs of another. Therefore, after various discussions, it was decided to start a small project at our site to explore the potential implementation of some of these features. The project is a work-in-progress.

This paper and the corresponding presentation will discuss some of the work done thus far. This includes specifying the particular features chosen for examination and any issues related to their implementation.

### Slurm Native Workload Management on Cray Systems

Danny Auble (SchedMD)

Cray’s Application Level Placement Scheduler (ALPS) software has recently been refactored to expose low level network management interfaces in a new library. Slurm is the first workload manager to utilize this new Cray infrastructure to directly manage network resources and launch applications without ALPS. New capabilities provided by Slurm include the ability to execute multiple jobs per node, the ability to execute many applications within a single job allocation (ALPS reservation), greater flexibility in scheduling, and higher throughput without sacrificing scalability or performance. This presentation includes a description of ALPS refactoring, new Slurm plugins for Cray systems, and the changes in functionality provided by this new architecture.

### Slurm RoadMap

Morris Jette (SchedMD), Yiannis Georgiou (Bull)

Slurm long-term development remains focused on the needs of high performance computing. The Slurm roadmaps continues to evolve as a greater understanding of unique Exascale computer requirements develops. For example, Exascale computers may well contain tens of thousands of compute nodes, which necessitates changes in Slurm communications infrastructure. Exascale power consumption will need to be carefully regulated with power capping, throttling the rate of change and managing the workload to maximize system utilization. This presentation will describe upcoming Slurm development plans.

### Umea University Site Report

Magnus Jonsson (Umea University)

Use of SPANK plugins to create a private temporary file systems for each job. This eliminates interference between jobs without the need to obey the TMPDIR environment variable. The module is using the features of private namespace/mount --bind in Linux.

### University of Warsaw Site Report

Marcin Stolarek and Dominik Bartkiewicz (Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), University of Warsaw, Poland)

- Our own SPANK plugins using unshare system call limit lustre availability for job
- SPANK plugin + prologue/epilogue preparing separate /tmp directory
- Job submit plugin which checks if job specification is "sane"
- Our work on integration of Slurm with middlewares in European and Polish grid infrastructures.

### iVEC Site Report

Andrew Elwell (iVEC)

iVEC (An unincorporated joint venture between CSIRO, Curtin University, Edith Cowan University, Murdoch University and the University of Western Australia and is supported by the Western Australian Government) provides supercomputing facilities and expertise to the research, education and industrial communities. Its new (2013) purpose built computing centre (the Pawsey Centre) houses several Cray XC30 systems as well as 6TB SGI UV2000, all connected via infiniband to multi-petabyte disk storage systems.

Although initially deployed with PBS Pro, senior management indicated that moving to SLURM as a unified centre-wide scheduler would be a good idea. This site report describes the issues faced by an operations team new to SLURM and the configuration choices that were made within the site.

Pawsey infrastructure runs with a single slurmdbd instance on KVM, with five different clusters using this as the accounting repository. The clusters are:

- Magnus, a Cray XC30 with 208 nodes, 2 external login nodes and 2 data mover nodes.
- Galaxy, a Cray XC30 with 472 nodes, 2 external login nodes, 2 data mover nodes and 16 'ingest' nodes
- Chaos, a small test and development XC30 but without any external nodes
- Zythos, the SGI UV2000 with 4 GPU cards
- Pawsey, used as a generic cluster to support 'copyq' partitions.

Because of the interaction between SLURM and ALPS/BASIL (the Cray node alllocation system) the cray-aware slurm binaries were compiled separately to the rest of the site (which uses a mixture of SLES and CentOS) with a patched 2.6.6 and 2.6.9 being deployed. Linux cgroups were used to control user access within shared nodes.

The report also covers some of the issues the users faced when migrating from PBS Pro, and the quirks associated with running on external login nodes with interactive jobs. Finally it describes some of the user facing reporting still under development

### CEA Site Report

Matthieu Hautreux (CEA)

CEA Site Report

### CSCS Site Report

Benini Massimo (CSCS)

CSCS Site Report

### Aalto University Site Report

Janne Blomqvist, Ivan Degtyarenko, Mikko Hakala (Aalto University)

We will present the computational science done at Aalto University, and the HPC infrastructure supporting this. Our cluster currently has around 550 compute nodes, with a mix of different hardware generations acquired at different points in time. The cluster is part of the Finnish Grid Initiative (FGI), a consortium of Universities and the national supercomputing center CSC - IT Center for Science, where FGI clusters are accessible to outside users via grid middleware. FGI also has a common base software stack. The funding of the Aalto HPC infrastructure is through a stakeholder model, where University departments using the cluster provide funding and manpower to run it. Currently there are three major departments that provide the core manpower and are responsible for the majority of the usage, but the cluster is also open to other users in the University without funding/manpower requirements as long as use remains moderate.

The funding model of the cluster results in pressure to show that resource usage is fair among the different departments, and to improve this we developed the ticket-based fairshare algorithm that has been included in upstream SLURM as of version 2.5 (originally called priority/multifactor2). We will present the ticket-based algorithm, and show how it achieves fairness in an account hierarchy.

We have also developed a wrapper for slurm user commands that some of our users have found easier to use than the "raw" slurm commands when investigating the state of the cluster. The wrapper is purely for read-only commands, so it is always safe to use.

### George Washington University

Tim Wickberg (George Washington University)

In particular, I would expect to elaborate and discuss usage of the fairshare scheduling system, including how it maps to our (slightly convoluted) internal funding model. Additional discussion may include our expected use / abuse of the generic resource scheduling system to dynamically allocate disk space on our test high-IOPS SSD scratch system.

Last modified 19 August 2014