Fusion Engineering and Design 60 (2002) 229–233

MDSplus. Current developments and future directions

Thomas W. Fredian *, Joshua A. StillermanMIT Plasma Science and Fusion Center, Massachusetts Institute of Technology, NW17-268, 175 Albany Street, Cambridge,

MA 02494, USA

Abstract

MDSplus is a data handling software system used widely in the fusion research community. It provides tools foracquiring, storing and analyzing data from fusion experiments, simulations, and analysis codes. The system alsoprovides a networking system that enables users to access data remotely from any computer on the Internet. Thesoftware is now available for most computing platforms. MDSplus is an open source package and as the usercommunity grows, many tools and programs based on MDSplus are being developed at numerous fusion researchsites. MDSplus is easily taught to access other data stores and is being used to provide a network gateway to fusiondata stored in non-MDSplus formats. Many large physics codes are being fitted to use MDSplus as the primarymeans of data input and output, removing the necessity to build different versions of the code to access different dataformats. This paper will describe where and how the software is currently being used, identify recent developmentsand enhancements to the system and present some of the planned improvements to the software. © 2002 ElsevierScience B.V. All rights reserved.

Keywords: Data acquisition; Remote participation; Data analysis

www.elsevier.com/locate/fusengdes

1. Background

MDSplus was developed as the result of col-laboration between C-Mod at MIT, RFX inPadova, Italy and ZTH in Los Alamos over thetime period of 1987–1991 [1]. The system wasdesigned and implemented to operate on theOpenVMS operating system with data acquisi-tion requirements of the order of 10–15megabytes per machine cycle. Key elements ofthe design included a hierarchical data storage,a built-in expression evaluator for doing trivial

conversions such as digitizer counts to volts, theability to store many different types and shapesof data in a single data store and extensibilityenabling sites to add customization such as sup-port for new data acquisition hardware withoutthe need to recompile or relink the MDSplussystem software.

MDSplus was first used on the C-Mod andRFX experiments in 1991–1992 and shortly af-ter adopted by the TCV experiment in Lau-sanne. The system worked well on theseexperiments and improvements in networkingand computer speeds have enabled the systemsto grow to handle the current data acquisitionloads now exceeding a few hundred megabytesper shot.

* Corresponding author. Tel.: +1-617-253-7623; fax: +1-617-253-0627.

E-mail address: twf@psfc.mit.edu (T.W. Fredian).

0920-3796/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.

PII: S0 920 -3796 (02 )00013 -3

T.W. Fredian, J.A. Stillerman / Fusion Engineering and Design 60 (2002) 229–233230

As more and more diagnostics were added to theexperiments and users began writing analysis pro-grams which would read data from the MDSplusstorage and write results back into the same areait became clear that the hierarchical tree structureof MDSplus data stores could prove to be veryvaluable. Users could readily find the data theywere interested in and they could even build anal-ysis programs and visualization tools that weredriven by the tree structure. An example of this isthe addition of an MDSplus interface to theTRANSP code [2]. TRANSP is a large analysiscode written and supported at PPPL. The code wasadapted at MIT to get input data from MDSplustrees and to write the results back into MDSplus.IDL applications were written to help the user dothe appropriate refinement of input data, run theTRANSP code and visualize the output of thecode. These applications used the hierarchicalstructure of the tree to determine the list of inputsand outputs and the types of operations that wereapplicable to this data. When new inputs or out-puts were added to the code, only the tree structureneeded to be modified. The applications using thisdata generally required no modification.

Not long after these experiments started operat-ing, scientists began collaborating from remotelocations. These scientists could connect via theInternet to local computers at the experiment andaccess the data, but they usually had computingresources at their remote sites that could be usedfor analyzing the data. More often than not theseremote computers were not OpenVMS systems somerely copying the binary data files would notprovide a solution. In 1994, MDSplus was en-hanced to provide a client/server data connectionto remote computers. A very small easily portedclient library was created which could communi-cate over the Internet to a server process runningon the OpenVMS computer that had access to theMDSplus data. This client library was ported tomany of the popular varieties of Unix and to theMS Windows platforms. Now it was possible forapplications running on the remote computersrunning a wide variety of operating systems toaccess MDSplus data. This remote access capabil-ity was demonstrated in a test where the AlcatorC-Mod experiment was controlled and operated

from a remote control room located at theLawrence Livermore National Laboratory in Cali-fornia [3].

The features of MDSplus were becoming attrac-tive to more and more sites but the restriction ofusing the OpenVMS operating system was a con-cern. Both General Atomics [4] and PPPL [5]agreed to assist in porting the system to the Unixplatform. During 1999–2000 the bulk of the MD-Splus system was ported to numerous Unix sys-tems and MS Windows. Since that time MDSplushas been installed at numerous sites on many typesof computer platforms (see Table 1). MDSplus isused in a variety of ways such as providing acomplete data acquisition and analysis system, orproviding data handling for analysis results only orproviding remote access capabilities to existingdata systems.

2. Recent MDSplus work

A core development team continues to enhancethe MDSplus system, expanding its availability onvarious computer platforms, increasing its robust-ness and enhancing its functionality.

2.1. Installation enhancements

Over the last year significant work has gone intomaking MDSplus easier to download and install.Binary kits for many varieties of Unix exist usingthe RPM (Redhat Package Manager) format. Asetup procedure is also available for installingMDSplus on Windows (95/98, NT and 2000). Inaddition, the build procedures for compiling andlinking MDSplus have been enhanced to make iteasier to build the software on a large variety ofplatforms.

2.2. New installations

There have been many new installations per-formed over the last year as is shown in Table 1.The growing base of MDSplus installations hasmade it easier for scientists to share data, analysisprograms and visualization tools. We anticipatethis growth will continue in the near future.

T.W. Fredian, J.A. Stillerman / Fusion Engineering and Design 60 (2002) 229–233 231

2.3. Ja�a applications

The MDSplus team in Padova has been devel-oping Java based applications for viewing andmanipulating experimental data. This includes en-hancements to the Jscope and Jtraverser applica-tions as well as new Java based action dispatcherand action monitor applications.

2.4. Large storage de�ice support

The MDSplus file access routines have beenenhanced to enable the system manager to modifythe algorithm used by MDSplus to locate the filesassociated with a particular pulse number. In thepast the system required the files to be located inone of a specified list of directories. A new mech-

anism was added such that the system managercould use digits of the pulse number combinedwith the tree name to specify the directory inwhich the files are to be found. This is importantfor both performance and management reasonswhen sites begin using large RAID systems, ar-rays of many magnetic disk drives.

2.5. Data acquisition support

Several extensions have been added to MD-Splus to enable the use of an ever-increasingselection of data acquisition equipment. Labviewvirtual instruments have been developed to enableusers to read and write MDSplus data using theNational Instruments Labview system. Devicesupport was also added to access VME shared

Table 1Current MDSplus installations

PlatformsFirst usedLocation Machine/code

C-ModMIT, Cambridge, MA OVMS, WNT, Linux, Tru64, MAC19911RFX 1991CNR, Padova, Italy OVMS, Tru64, Solaris, Linux, WNT, vxWorks2TCV3 1992EPFL, Lausanne, Switzerland OVMS, LinuxPTF4 1995MIT, Cambridge, MA OVMS

OVMS, Solaris1996HANBIT5 Taejon, South Korea6 General Atomics, San Diego, CA DIII-D 1997 Tru64, HPUX, Linux, WNT, IRIX, OVMS, MacOS7 OVMS, Solaris, Tru64, Linux, WNT1997NSTXPPPL, Princeton, NJ

1998ZaP Linux, WNT, OVMS, Tru64U of Washington, Seattle, WA89 U of Washington, Seattle, WA HIT 1998 Linux, WNT, OVMS, Tru64

U of Washington, Seattle, WA TIP10 1998 Linux, WNT, OVMS, Tru6411 ANU, Canberra, Australia H1 1999 OVMS, Tru64, Linux, WNT

Tru64Frascati, Italy 199912 FTUUKAEA/EFDA, UK JET13 2000 Linux, Solaris

14 Tianjin University of China, WNTHT-7U 2000PRC

CHS15 2000NIFS, Toki, Japan OVMS, Tru64, WNT16 PISCESUCSD, San Diego, CA 2000 WNT

Linux, SGI Irix, Cray Unicos200017 NIMRODSAIC, San Diego, CA200118 MIT, Cambridge, MA LDX OVMS, MAC200119 Columbia U, NY, NY HBT-EP OVMS, WNT2001 OVMS, WNTCTX20 Columbia U, NY, NY

T-10Kurcatov Institute, Moscow, Linux200121Russia

MTFLANL, Los Alamos, NM SunOS22 2001SunOS2001FRX-LLANL, Los Alamos, NM23

U of Washington, Redmond, TCS24 2001 WNT, MAC, OVMSWA

200125 Cray T3ELBL, Oakland, CA NIMRODMST 2001 OVMS26 U of Wisconsin, Madison, WI

T.W. Fredian, J.A. Stillerman / Fusion Engineering and Design 60 (2002) 229–233232

memory modules to support the CINOS subsys-tems developed for the CHS experiment atNIFS. A MS Visual Basic interface to MDSpluswas also developed to enable users to read andwrite MDSplus data from Visual Basic applica-tions on windows systems.

Support was added to MDSplus to performdata acquisition using compact PCI based tran-sient recorders [6]. These systems are based onPCs running the Linux operating system. AnMDSplus system is run on the PC and can beused as standalone data acquisition system orcan be controlled remotely using the MDSplusremote access capabilities.

Support for accessing CAMAC using eitherthe Jorway 411 SCSI Serial Highway Driver orthe Kinetic Systems 2145 SCSI Serial HighwayDriver has been developed for the Linux plat-form. The software that emulates the originalORNL CAMAC library utilizes the genericSCSI driver available on Linux. This package isin final testing and will be included in the MD-Splus distribution and CVS source code reposi-tory in the near future.

2.6. Analysis codes

Many widely used analysis codes are beingconverted to use MDSplus as the vehicle fordata input and output. The codes will then havea standard mechanism for accessing data andcan use the built in remote access capability ofMDSplus to access data anywhere on the Inter-net. The user of the code can use familiar datamanipulation and visualization tools on both theinputs and outputs of the code. Some of thecodes modified include: TRANSP, PEST, GS2,LIUQE, TORAY, EFIT, NIMROD,ONETWO, GATO, GKS, CER analysis codes.

3. Future Enhancements

3.1. Globus/Akenti security/authentication

The remote access capability available in MD-Splus currently uses a very rudimentary authen-tication method. As the size of the MDSplus

community grows and the use of MDSplusclient/server communications expands to providedata access to fusion research data and comput-ing services, it is becoming more important toprotect these valuable resources against unau-thorized use. Over the next 2 years we plan toexploit the state-of-the-art, certificate based, au-thentication, authorization, and encryption tech-nologies provided by the Globus SecurityInfrastructure [7] and the Akenti authorizationservice in the MDSplus client/server communica-tion system.

3.2. MDSplus documentation/FAQ system

While there are numerous documents [8]available describing MDSplus at various MD-Splus installation sites, the MDSplus documen-tation is still quite sparse and unorganized. Weplan to reorganize the existing documentationand add an MDSplus frequently asked questions(FAQ) system. A web based FAQ system hasbeen developed at General Atomics in SanDiego that uses an MS SQL Server database toorganize the information. We hope to use thissystem to present the MDSplus FAQ informa-tion. We also are bringing online a new Linuxbased server system which will be used to serverthe MDSplus documentation, cvs repository andbinary kit distribution.

3.3. Additional data acquisition de�ice support

The SCSI CAMAC Serial Highway supportwill be ported to other Unix platforms andWindows where generic SCSI drivers are avail-able.

4. Conclusions

The MDSplus system is now widely usedthroughout the worldwide fusion research com-munity. It provides a uniform remote data ac-cess capability to experimental and analysisdata. It is expected that the number of users ofthis software will continue to grow. MDSplusdevelopment is no longer limited to the original

T.W. Fredian, J.A. Stillerman / Fusion Engineering and Design 60 (2002) 229–233 233

authors and numerous sites are developing MD-Splus based tools that should prove useful tothe entire fusion sciences community.

The remote access capabilities of MDSplusmake it easy to share the valuable fusion re-search resources, namely data and computing fa-cilities. A major task ahead of us is to ensurethat these resources are protected from unautho-rized access. We hope to solve this problem us-ing modern certificate based encryption andauthentication methods in the near future.

MDSplus is quite flexible and powerful andcan support a wide variety of data handlingneeds. Unfortunately the knowledge required fortapping many of its capabilities is distributedquite inefficiently, either by word of mouth oremail exchanges. With the help of the MDSpluscommunity we hope to begin to build a muchmore extensive online MDSplus documentationset which can guide a user from the early stages

of MDSplus use through the use of some of thesystems more advanced functionality.

References

[1] J.A. Stillerman, T.W. Fredian, K.A. Klare, G. Manduchi,MDSplus data acquisition system, Review of ScientificInstruments 68 (1) (1997).

[2] J. Schachter, Local Transport Analysis for the AlcatorC-Mod tokamak, MIT Plasma Science and Fusion CenterPhD Thesis, PSFC/RR-97-12, 1997.

[3] S. Horne, et al., Remote control of Alcator C-Mod fromLLNL, Fusion Technology 32 (1997) 152.

[4] http://fusion.gat.com/comp/analysis/mdsplus/[5] http://nstx.pppl.gov/nstx/Software/[6] J.A. Stillerman, T.W. Fredian, Compact PFC based data

acquisition with MDSplus, in: Proceedings of the 3rd IAEA.[7] I. Foster, C. Kesselman, Globus: A Toolkit-Based Grid

Architecture in The Grid: Blueprint for a New ComputingInfrastructure, Morgan Kaufmann, 1999, pp. 259–278.

[8] http://www.mdsplus.org/