Grid Lingo - in glideinWMS context

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This talk provides basic Grid definitions, within the glideinWMS ecosystem.

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Grid Lingo - in glideinWMS context

  1. 1. glideinWMS training The Grid lingo with a particular emphasis on the Open Science Grid. And how it relates to glideinWMS. by Igor Sfiligoi (UCSD)glideinWMS training glideinWMS - The Larger Picture 1
  2. 2. Why this talk? We will be using a lot of Grid terminology in the other glideinWMS talks. This talk provides the definitions for the most used acronyms allowing you to understand those talks.glideinWMS training glideinWMS - The Larger Picture 2
  3. 3. Grid computing ● Grid computing is usually defined as a federated set of HTC clusters sharing a common (set of) middleware ● There are many implementations of “Grids” ● We will concentrate on Open Science Grid (OSG) ● OSG is the most used Grid by glideinWMS (a close second is EGI, but it is quite similar to OSG)glideinWMS training glideinWMS - The Larger Picture 3
  4. 4. OSG Building Blocks ● OSG is composed of a set of independent HTC cluster providers ● Also called sites ● There is no central command-and-control ● OSG organization provides to HTC operators ● A software stack, containing a well defined set of middleware packages ● A common security infrastructure, i.e. authentication and authorization mechanisms ● Plus other support servicesglideinWMS training glideinWMS - The Larger Picture 4
  5. 5. OSG Software ● OSG clearly separates computing resources from storage resources ● We are only interested in computing ones for the purpose of glideinWMS ● Each HTC cluster has ● A Compute Element (CE), which OSG software submits to the local HTC system installed on all ● A set of worker nodes, where of them compute jobs runglideinWMS training glideinWMS - The Larger Picture 5
  6. 6. The CE ● The CE is the only externally accessible service ● Provides an abstraction layer to the site-local HTC system ● OSG provides the Globus Gatekeeper, has recently transitioned from v2 to v5 (gt2 & gt5) ● OSG clients also support the EGIs CREAM Repository Worker node Worker node CE Scheduler Worker node Worker nodeglideinWMS training glideinWMS - The Larger Picture 6
  7. 7. Security mechanisms ● OSG mandates x.509 certificates Same mechanism for service and user authentication as used by HTTPS ● Based on Public Key Cryptography (PKI) ● User is given a certificate with a unique Distinguished Name (DN) ● The user authorization is role based, and handled by VOMS ● VOMS=Virtual Organization Management System ● A service for granting extended attributesSee “Security in OSG” talk for more details http://www.slideshare.net/igor_sfiligoi/osg-school-2012-security-in-osgglideinWMS training glideinWMS - The Larger Picture 7
  8. 8. What are Virtual Organizations? ● Basically, a well defined group of people sharing a common interest ● In OSG, we expect them to also have ● Some internal governance ● Appoint trustworthy security contact ● Run VO-specific services (e.g. VOMS) ● Example OSG VOs ● The High Energy CMS experiment (single science, worldwide) ● The Holland Computing Center (single location, multiple sciences)glideinWMS training glideinWMS - The Larger Picture 8
  9. 9. Back to glideinWMS ● glideinWMS creates an overlay system on top of the various HTC clusters HTC ● From the VO point of view, HTC a single HTC system glideinWMS HTC HTC ● Just a dynamic one HTC ● glideinWMS HTC completely automates the process See “Larger Picture” talk for more details http://www.slideshare.net/igor_sfiligoi/glideinwms-the-larger-pictureglideinWMS training glideinWMS - The Larger Picture 9
  10. 10. A little more complicated than that ● The previous slide could led you to believe that there can only be one overlay ● In reality, there can be any number of them! ● Each serving its own user community ● Not necessarily all using gwms 1 HTC the same set HTC of HTC clusters HTC gwms 2 HTC gwms 3 HTCglideinWMS training glideinWMS - The Larger Picture 10
  11. 11. Why many glideinWMS instances? ● VOs typically dont want to share a glideinWMS HTC instance ● While technically possible, there are ● Security risks ● Increased maintenance complexity ● Politics! ● Typically we get one glideinWMS HTC instance per VO ● But some VOs have more than oneglideinWMS training glideinWMS - The Larger Picture 11
  12. 12. Acknowledgments ● This document was sponsored by grants from the US NSF and US DOE, and by the UC systemglideinWMS training glideinWMS - The Larger Picture 12

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