Jon Wakelin

Condor, Globus and SRB:Tools for Constructing a Campus Grid

2 Overview

• Condor

• Globus

• Storage Resource Broker (SRB)

• UoBGrid

• Summary

3 Condor Overview

• High Throughput Computing Environment– From networked resources (Condor pool)

• Like other Schedulers– Queuing mechanism– Prioritisation scheme– Scheduling Policy

• Unlike other schedulers– Doesn’t need dedicated resources– Desktops workstations, library or PC lab computers – Cycle scavenging

4 Class Ads

• Classified advertisements– Machine Class Ads (for sale)– Job Class Ads (wanted)

• Machine Class Ads– Created from information “advertised” by machines in the condor pool

– Can add extra Class Ad information

• Job Class Ads – Created from information in the condor submit file

– Created from default values

5 Different roles in a Condor pool

• Central Manager

• Submit

• Execute

• Or a combination of these

– e.g. submit and execute node

• Different daemons will be started depending on the role of the machine

6 Condor Daemons

• All Machines– condor_master - controls other daemons

• Central Manager– condor_collector - Collects information from other machines– condor_negotiator - Performs matchmaking

• Execute– condor_startd - Starts, stops, suspends jobs

• Submit– condor_schedd - Maintains queue of jobs

7 Job Submission

Executable = /bin/lsArguments = -lInitialDir = /usr/bin

Output = outError = err

Queue

8 Job Submission

Executable = /bin/lsArguments = -lInitialDir = /usr/bin

Output = out.$(Process)Error = err.$(process)

Queue 2

9 Job Submission

Executable = /bin/lsArguments = -lInitialDir = /usr/bin

Output = out.$(Process)Error = err.$(process)

Requirements = ((Arch==“INTEL” && OpSys=“LINUX”) || (Arch==“INTEL” && OpSys=“IRIX65”))

Queue 2

10 Job Submission

Executable = gaussian.$$(Arch).$$(OpSys)InitialDir = /home/jon

Input = chlorobenzene.inOutput = chlorobenzene.$(Process)Error = chlorobenzene.$(process)

Requirements = ((Arch==“INTEL” && OpSys=“LINUX”) || (Arch==“INTEL” && OpSys=“IRIX65”))

Queue 2

11 Condor Commands

• condor_submit <submit_file>

• condor_q

• condor_rm

• condor_status– Displays pool status in a succinct format

• condor_status –l <machine>– Display full Class Ad information

12 Condor-G

• Condor interface to access Globus resources– condor submit file– condor commands– Keeps log of runs– Adds fault tolerance

• Can be used to perform matchmaking– Must create machine Class Ads manually– condor_advertise command– Can be used to create a resource broker– No RB functionality in Globus Toolkit

13 Globus Toolkit Overview

• Globus is a toolkit not an turnkey solution

• Globus Toolkit 2.4.3 common choice for production grids

• Four main components– Authentication (GSI)– Resource management (GRAM)– Data transfer (GridFTP)– Resource discovery and monitoring (MDS)

14 Authentication

• Grid users need to obtain something called a

certificate

• Applications can use the certificate to establish the

identity of the user….

• i.e. authenticate the user

15 PKI Authentication

• Public Key Infrastructure– Public/Private keys– Used to encrypt data– And to sign certificates

• Certification Authority (CA)– User create certificate– CA Signs certificates– UK eScience CA at RAL

• Certificate Contains– Identity/Distinguished Name (DN)– Public Key– signature & Identity of CA

16 GSI Authentication

• Grid Security Infrastructure– extensions to PKI (X509, SSL extensions)– Single sign-on– Delegation

– grid-proxy-init – command to create proxy certificates

CA User Proxy

Signature Signature

17 Resource Management (GRAM)

• Grid Resource Allocation Manager– Gatekeeper– Resource Specification Language– JobManagers

18 GRAM - Gatekeeper

• Daemon runs on a grid resource

• Processes incoming globus requests

• Authenticates Users– Configured to trust a given CA– e.g. UK eScience CA at RAL

• Maps user to local account– DN => username – grid-mapfile

• Passes the job onto the jobmanager

19 GRAM - RSL

• Resource Specification Language– (attribute op value) in parenthesis

• Operators– Numerical operators within clauses (<, <=, >, >=, =, !=)– Logical operators between clauses (&, | )

• Attributes– Predefined

• executable, arguments, stdin, stdout, stderr, environment• maxCpuTime, maxWallTime, maxMemory, project, queue

– User defined• May be handled by subsequent application

20 GRAM - RSL

&(executable=“/bin/ls”) (arguments=“-l”) (directory=“/usr/bin”)

21 GRAM - JobManagers

• Perl modules– Convert RSL into scheduler specific language

• Reference implementations– Fork, Condor, PBS, LSF

• May need to roll-your-own– e.g. LoadLeveller, SGE– Or just to add extra functionality

22 Data Management (GridFTP)

• File Transfer Protocol– Extension of the standard FTP protocol stack to include extra

functionality• GSI authentication• Third Party transfers• Striped transfers

– User application is globus-url-copy

23 Information Services (MDS)

• Collect and provide status information about Grid resources

• MDS: Monitoring and Discovery Service– GRIS: Grid Resource Information Service

• Collects info about local resource• Reports to GIIS server

– GIIS: Grid Index Information Service• Aggregates information from GRIS servers• One per organisation

– Same executable with different configuration

24 Storage Resource Broker (SRB) Overview

• Uniform interface to heterogeneous data storage resources– Unix, Irix, linux file systems– Windows– Databases– Physical media (tape storage)

• SRB is middleware– Allows access to a wide range of data resources– Allows a wide range of user Apps to be written – All accessed through a “narrow” API

API

Storage

Applications

25 SRB Access

• Applications– Scommands: command line– MySRB: Web access– inQ: Windows GUI

• APIs– Java, C, C++, Python, Perl

26 UoBGrid Overview

• What is a Campus Grid?

• Our Situation

• Software Choices

• Services

27 What is a Campus Grid?

• A Grid: Single sign-on to multiple resources located in different

administrative domains

28 Our Situation

• Dedicated departmental clusters– Windows Condor pools not a requested resource

• Separation of user communities– parallel vs serial usage

• All contained within a single firewall domain

• Wanted to become partners in the NGS– Systems must be compatible– Encourage our users to become NGS users

• Full Economic Costing coming soon!– Important to keep usage records– Ensure best usage of purchased resources for sustainable future

29 Software Choices

• Condor 6.6.7• Globus 2.4.3• MyProxy• GSI-SSH• Storage Resource Broker (SRB)

• Virtual Data Toolkit (VDT)– Bundles many useful tools– Platform independent installation– Supported release of Globus Toolkit, MyProxy & GSI-SSH

30 Planned Resources

31 Current Resources

• 4 Servers– RB: Resource Broker– VOM: Virtual Organisation Manager– MDS: Monitoring and Discovery Service– SRB: Storage Resource Broker

• 4 Compute Resources– Monster2 - SGE, 20 CPU– Tuya - PBS, 16 CPU– Grendel - PBS, 110 CPU– BSESrv1 - PBS, 28 CPU

32 Resource Broker

• Condor-G with matchmaking

• Custom script for determination of resource status– Converts MDS information into condor Class Ads– Adds information about available software

• User submission script– Create condor submit file – Software requirements passed into Condor submit file– Submits jobs– Sends data SRB

• http://cerb-rb.bris.ac.uk/cgi-bin/rb_status.cgi

33 Virtual Organisation Manager

• Built using– Webserver

• Apache + mod_ssl • Perl CGI

– Postgres Database– Modified Globus JobManagers

• Functionality– Record of users and machines– Administrative functions– Accounting/Usage Statistics

34 Virtual Organisation Manager

• Admin – via web interface (https)– Access based on Certificate/DN– Add/remove Users– Add/Remove Resource– Control Users Access to Resources

• Constructs grid-mapfiles for all resources

• https://cerb-vom.bris.ac.uk/vom-bin/VOM.cgi

35 Virtual Organisation Manager

• Accounting/Usage Statistics– Usage by machine

– Usage by users

• Modified GRAM JobManagers– Job details sent to DB on completion– executable, arguments, start time, end time, CPU, wall time, memory,

virtual memory, jobmanager-type, number of nodes

• http://cerb-vom.bris.ac.uk/cgi-bin/VOM-usage-stats.cgi

36 Resource Monitor

• Runs GIIS– Collects information from UoBGrid resources

• Runs Big Brother monitoring software– Client/Server model– Server pings registered resources– Client records local system info and reports to server

37 Big Brother Monitoring System

Web available

status page with

easy to

understand

functionality for

helpdesk and

admin staff.

38 Storage Resource Broker

• All UobGrid users given SRB account

• GSI authentication enabled for Scommands

• Access via certificate

39

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

UoB Grid

40

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

Compute resources running GRIS report to information servers

41

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

Resource Broker polls information servers and convertsMDS information into Condor Class Ads

42

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

User logs on to Resource Broker to submit job. JobsAre matched to resources using condor

43

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

Job details sent to machine by Condor-G

44

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

Upon completion output files are sent back to the Resource broker

45

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

If job runs on UoB Grid resources run details are sent to VOM DBFor NGS and UoB users alike.

46

SRB

MDS

RB

VOM

User

RAL Oxford

Leeds Man

Monster2 (SGE)

bserv (PBS)

Grendel (PBS)

Tuya(PBS)

BDII

NGS

Finally output file are sent from RB to the Storage Resource Broker

47 Summary

• Condor– Standalone: high throughput computing system

– Matchmaking with Class Ads

– Condor-G: interface to Globus Toolkit

• Globus Toolkit– Applications, Protocols, APIs

– GSI – Certificates (DN, public key, digital signature)

• UoBGrid– Centralised access to disparate resources

– Custom components created to fill functionality gaps

– Globus gives authenticated access to resources

– Condor provides matchmaking (i.e. brokering)

– SRB provides storage

48 Useful URLs

• SRB: http://www.sdsc.edu/srb/

• Globus: http://www.globus.org/

• Condor: http://www.cs.wisc.edu/condor/

• UK eScience CA: https://ca.grid-support.ac.uk/

• NGS: http://www.ngs.ac.uk/

• UoBGrid: http://escience.bris.ac.uk