On Tue, 1 Mar 2005, Laurence wrote:
> Hi,
>
> We touched upon this issue during a recent Glue Schema discussion.
>
> With most VOs, the software manager will install the VO software on the
> site and publish a tag in the RuntimeEnvironment so that the VOs jobs
> can then be steered to that site. The information could be used to help
> the VO manger install the software but they should run some kind of
> probe job at the site to check if what they require is on the worker
> node.
>
The idea of using the IS not only for steering jobs to run in
the site but also for helping ESM to install software, has been taken
into account in our internal (EIS team) discussion about a
general mechanism for Experiment Software Installation.
We started from another point of view: the Tank and Spark mechanism
and the question:
"How the experiment software manager does know when the software has been
fully and successfully propagated to all WNs?"
The ESM must be sure that his software is present in all WNs
(sharing or not a file system) and - even more worth - that he/she KNOWS
the status of the installation.
For that we have implemented (using the currently deployed tools like
lcg-ManageVOTag) a multi-step publication of the tag.
Each step will publish the status of installation having its own "flavor"
and removes the previous one.
For instance, by considering that the syncronization of GigaBytes of
experiment software among hundred of WNs might take quite a long time, we
decided to publish a tag like:
VO-<vo_name>-TAG-installing
After that, Tank ends its task, it changes (removes and adds) this
temporary tag by setting it to something like:
VO-<vo_name>-TAG-novalidated
indicating that the ESM can run on this site the validation process.
The ESM validation process will finally publish the tag which certifies
the site for this software by replacing the last tag with the usual one
VO-<vo_name>-TAG.
> Laurence
>
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EUROPEAN LABORATORY FOR PARTICLE PHYSICS -- CERN
Roberto Santinelli
IT/GD Division
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