gLite Information System and Workload Management System

1
gLite Information System and Workload Management
System

• Diego Scardaci
• INFN Catania
• International Summer School on Grid Computing
• Ischia, 9-21 July, 2006

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Outline

• Information System Architecture
• Berkeley DB Information Index (BDII)
• The Relational Grid Monitoring Architecture
  (RGMA)
• Workload Management System
• WMS Architecture
• Job Description Language Overview
• WMProxy Overview
• Special Jobs DAG, Collections, Parametric and
  MPI

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Information System
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Information System

• What is?
• System to collect information on the state of
  resources
• Why?
• To discover resources of the grid and their
  nature
• To have useful data in order to who is in charge
  of managing the workload to do it more
  efficiently.
• To check for health status of resources.
• How?
• Monitoring state of resources locally and
  publishing fresh data on the information system.
• Adopting a data model that MUST be well known to
  all components that want to access monitored
  information
• Using different approaches that we are going to
  investigate in the next slides

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Adopted Information Systems

• The BDII (Berkeley DB Information Index)
• has been adopted in LCG middleware as the
  Information System provider.
• It is an evolution of the Globus Meta Directory
  System (MDS)
• It is based on Lightweight Directory Access
  Protocol (LDAP) servers.
• The Relational Grid Monitoring Architecture
  (R-GMA)
• It is an implementation of the Grid Monitoring
  Architecture (GMA) standardized by the Global
  Grid Forum (GGF, now OGF)
• It is a relational implementation of the GMA
• It is strongly Web Services Oriented
• It uses standard SQL query syntax

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GRISs, local BDII and BDII


Abbreviations BDII Berkeley DataBase
Information Index GIIS Grid Index Information
Server GRIS Grid Resource Information Server
Each site can run a BDII. It
collects the information given by the local
BDIIs At each site, a local BDII collects
the information given by the GRISs Local
GRISes run on CEs and SEs at each site and report
dynamic and static information
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The IS in gLite
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BDII

• Users and other Grid services (such as the RB)
  can interrogate BDIIs to get information about
  the Grid status.
• Each BDII collects information from the site
  GIISes (or local BDII) defined in a configuration
  file, which it accesses through a web interfaces.
• Every two minutes a cron-job runs a script and
  collects information (pull model) from all the
  GIIS (local BDII) listed in the configuration
  file

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R-GMA

• The Relational Grid Monitoring Architecture
  (R-GMA)
• It is the relational implementation of GMA
  defined by the GGF
• Adopts a database model with tables and relations
  between tables
• Implements a virtual database
• The user queries the R-GMA as he/she was querying
  to a classical database (SQL string)
• Implements different type of queries
• The information
• The Producer stores its location (URL) in the
  Registry.
• The Consumer looks up producer URLs in the
  Registry.
• The Consumer contacts the Producer to get all the
  data or to listen for new data.

Store location
Transfer Data
Lookup location
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Workload Management System
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Outline

• Overview of WMS Architecture
• Job Description Language Overview
• WMProxy Overview
• Special Jobs
• DAG jobs
• Job collections
• Parametric jobs
• MPI jobs

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WMS Objectives

• The Workload Management System (WMS) comprises a
  set of Grid middleware components responsible for
  distribution and management of tasks across Grid
  resources.
• The purpose of the Workload Manager (WM) is
  accept and satisfy requests for job management
  coming from its clients
• meaning of the submission request is to pass the
  responsibility of the job to the WM.
• WM will pass the job to an appropriate CE for
  execution
• taking into account requirements and the
  preferences expressed in the job description file
• The decision of which resource should be used is
  the outcome of a matchmaking process.

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WMS Architecture
Keeps submission requests Requests are kept
for a while if no resources are immediately
available
Repository of resource information available to
matchmaker Updated via notifications and/or
active polling on resources
Job management requests (submission,
cancellation) expressed via a Job
Description Language (JDL)
Finds an appropriate CE for each submission
request, taking into account job requests and
preferences, Grid status, utilization policies
on resources
Performs the actual job submission and
monitoring
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Job Description Language
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Job Description Language

• In gLite Job Description Language (JDL) is used
  to describe jobs for execution on Grid.
• The JDL adopted within the gLite middleware is
  based upon Condors CLASSified Advertisement
  language (ClassAd).
• A ClassAd is a record-like structure composed of
  a finite number of attributes separated by
  semi-colon ()
• A ClassAd is highly flexible and can be used to
  represent arbitrary services
• The JDL is used in gLite to specify the jobs
  characteristics and constrains, which are used
  during the match-making process to select the
  best resources that satisfy jobs requirements.

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Job Description Language (cont.)

• The JDL syntax consists on statements like
• Attribute value
• Comments must be preceded by a sharp character
• ( ) or have to follow the C syntax
• WARNING The JDL is sensitive to blank
• characters and tabs. No blank characters
• or tabs should follow the
• semicolon at the end of a line.

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JDL an example
Type "Job" JobType "Normal" Executable
"startGen4.sh" Environment "CLASSPATH./gfal.j
ar./gint.jar","LD_LIBRARY_PATH.LD_LIBRARY_PATH
","LCG_GFAL_VOgilda","LCG_RFIO_TYPEdpm" Argume
nts " 0 0 10 4 10000 aliserv6.ct.infn.it
lfn/grid/gilda/valeria/2000pillar.dat
/gilda/ischia06/vardizzo" StdOutput
"sample.out" StdError "sample.err" InputSandbo
x "startGen4.sh","gint.jar","gfal.jar","libGFal
File.so" OutputSandbox "sample.err","sample.o
ut" Requirements Member("GLITE-3_0_0",other.Gl
ueHostApplicationSoftwareRunTimeEnvironment)
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Workload Manager Proxy
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WMProxy

• WMProxy (Workload Manager Proxy)
• is a new service providing access to the gLite
  Workload Management System (WMS) functionality
  through a simple Web Services based interface.
• has been designed to handle a large number of
  requests for job submission
• gLite 1.5 gt 180 secs for 500 jobs
• goal is to get in the short term to 60 secs for
  1000 jobs
• it provides additional features such as bulk
  submission and the support for shared and
  compressed sandboxes for compound jobs.
• Its the natural replacement of the NS in the
  passage to the SOA approach.

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New request types

• Support for new types strongly relies on newly
  developed JDL converters and on the DAG
  submission support
• all JDL conversions are performed on the server
• a single submission for several jobs
• All new request types can be monitored and
  controlled through a single handle (the request
  id)
• each sub-jobs can be however followed-up and
  controlled independently through its own id
• Smarter WMS client commands/API
• allow submission of DAGs, collections and
  parametric jobs exploiting the concept of shared
  sandbox
• allow automatic generation and submission of
  collections and DAGs from sets of JDL files
  located in user specified directories on the UI

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Special Jobs
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Outline

• DAG
• Job Collection
• Parametric jobs
• MPI jobs on gLite

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DAG job

• A DAG job is a set of jobs where input, output,
  or execution of one or more jobs can depend on
  other jobs
• Dependencies are represented through Directed
  Acyclic Graphs, where the nodes are jobs, and the
  edges identify the dependencies

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JDL structure
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Attribute Nodes
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Attribute Dependencies
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DAG jdl
type "dag" max_nodes_running 4
nodes nodeA file
"nodes/nodeA.jdl" nodeB
file "nodes/nodeB.jdl" nodeC
file "nodes/nodeC.jdl" nodeD
file "nodes/nodeD.jdl"
dependencies nodeA, nodeB,
nodeA, nodeC, nodeB,nodeC, nodeD

Node description could also be done here, instead
of using separate files
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Job Collection

• A job collection is a set of independent jobs
  that user wants to submit and monitor via a
  single request
• Jobs of a collection are submitted as DAG nodes
  without dependencies
• JDL is a list of classad, which describes the
  subjobs

Type "collection" VirtualOrganisation
gilda" nodes ltjob descr 1 gt,
ltjob descr 2 gt,
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Scattered Input Sandboxes

• Input Sandbox can contain
• file paths on the UI machine (i.e. the usual way)
• URI pointing to files on a remote gridFTP/HTTPS
  server
• A base URI to be applied to all sandbox files can
  also be specified
• Only local files (file//) are uploaded to the
  WMS node
• File pointed by URIs are directly downloaded on
  the WN by the JobWrapper just before the job is
  started

InputSandbox "gsiftp//neo.datamat.it2811/va
r/prg/sim.exe", "https//ghemon.cnaf.infn.it8443
/data/idat_1", "file///home/pacio/myconf
InputSandboxBaseURI "gsiftp//matrix.datamat.it
2811/var"
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Scattered Output Sandboxes

• JDL has been enriched with new attributes for
  specifying the destinations for the files listed
  in the OutputSandbox attribute list
• A base URI to be applied to all sandbox files can
  also be specified
• Files are copied when the job has completed
  execution by the JobWrapper to the specified
  destination without transiting on the WMS node

OutputSandbox "jobOutput", "run1/event1",
"jobError" OutputSandboxDestURI
"gsiftp//matrix.datamat.it/var/jobOutput", "h
ttps//grid003.ct.infn.it8443/home/cms/event1",
"gsiftp//matrix.datamat.it/var/jobError"
OutputSandboxBaseDestURI "gsiftp//neo.datamat.i
t/home/run1/"
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Job collection example
type "collection" InputSandbox
"date.sh" RetryCount 0 nodes
file "jobs/job1.jdl" ,
Executable "/bin/sh" Arguments
"date.sh" Stdoutput "date.out" StdError
"date.err" OutputSandbox "date.out",
"date.err" , file
"jobs/job3.jdl"
All nodes will share this Input Sandbox
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Parametric Job

• A parametric job is a job where one or more of
  its attributes are parameterized
• Values of attributes vary according to a
  parameter
• Job monitoring / managing is always done through
  an unique jobID, as if the job was single (see
  submission of collection

JobType "Parametric" Executable
"/bin/sh" Arguments "md5.sh
input_PARAM_.txt" InputSandbox "md5.sh",
"input_PARAM_.txt" StdOutput
"out_PARAM_.txt" StdError "err_PARAM_.txt"
Parameters 4 ParameterStart 1
ParameterStep 1 OutputSandbox
"out_PARAM_.txt", "err_PARAM_.txt"
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Parametric job / 2

• Parameter can be also a list of string
• InputSandbox (if present) has to be coherent with
  parameters

ui-test /home/giorgio/param gt cat param2.jdl
JobType "Parametric" Executable
/bin/cat" Arguments input_PARAM_.txt
InputSandbox "input_PARAM_.txt"
StdOutput "myoutput_PARAM_.txt" StdError
"myerror_PARAM_.txt" Parameters
earth,moon,mars OutputSandbox
myoutput_PARAM_.txt ui-test
/home/giorgio/param gt ls inputEARTH.txt
inputMARS.txt inputMOON.txt param2.jdl
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MPI Overview

• Execution of parallel jobs is an essential issue
  for modern informatics and applications.
• Most used library for parallel jobs support is
  MPI (Message Passing Interface)
• At the state of the art, parallel jobs can run
  inside single Computing Elements (CE) only
• several projects are involved into studies
  concerning the possibility of executing parallel
  jobs on Worker Nodes (WNs) belonging to different
  CEs.

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References

• gLite 3.0 User Guide
• https//edms.cern.ch/file/722398/1.1/gLite-3-UserG
  uide.pdf
• R-GMA overview page
• http//www.r-gma.org/
• GLUE Schema
• http//infnforge.cnaf.infn.it/glueinfomodel/
• JDL attributes specification for WM proxy
• https//edms.cern.ch/document/590869/1
• WMProxy quickstart
• http//egee-jra1-wm.mi.infn.it/egee-jra1-wm/wmprox
  y_client_quickstart.shtml
• WMS user guides
• https//edms.cern.ch/document/572489/1