ARC Compute Element Release EMI-1 "Kebnekaise" Notes

What's new:

ARC Compute Element (ARC CE) in EMI-1 "Kebnekaise" release is a major step forward with respect to previous releases, as it completes migration to the new code base introduced by KnowARC. Grid Manager service, which was at the heart of ARC CE for a decade, is completely refactored and re-engineered, while keeping all of its key features that made it so reliable and attractive, including automatic data caching and staging. Grid Manager replacement is called A-REX (for ARC Resource-coupled EXecution service), which is a more sustainable, scalable and extendible (e.g. via plugins) solution. While preserving backwards interface compatibility, A-REX also provides a new WS-based interface, which is a step towards a common EMI execution service interface to be exposed by all Compute Elements. Among other new features, information publishing according to the GLUE2 specification is enabled, both via WS interface and LDAP, and a support for new back-end for the EDGI 3GBridge is added. Among experimental features, improved input/output data handling framework and ARGUS authorisation plugin should be mentioned: though not turned on by default, they offer preview of technologies to come in next releases.

In total, 48 bugs in A-REX and associated components were fixed since the previous ARC CE release in October 2010. These included fixing configuration issues, problems with handling of some job description attributes (both JSDL and xRSL), glitches in some internal job states, and improving performance and functionality of batch system interfaces. Complete list of fixes is available in ARC 11.03 Release Notes.

Deployment notes:

For sites deploying ARC 0.8.3 or ARC 0.8.3.1 releases, a smooth upgrade path via Yum is provided. Since this will imply switch from Grid Manager to A-REX, careful check is advised. Please refer to Grid Manager EOL notes for details.

To get A-REX you need to install the new "nordugrid-arc-arex" package and start the service with /etc/init.d/a-rex start (there is a compatibility grid-manager symlink provided too). By default, A-REX uses configuration file from the old Grid Manager. Configuration instructions are available in A-REX documentation (NORDUGRID-TECH-14).

Known Issues:

  • Janitor module for dynamic runtime environment management is not ready for this release
  • GLUE2 XML document is incomplete due to the absence of official XML rendering

License:

ARC CE components are released under Apache v2.0 license

-- OxanaSmirnova - 18-Feb-2011

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Topic revision: r1 - 2011-02-22 - OxanaSmirnova
 
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