Notes on the gLite production and deployment 
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People :

- Oliver Keeble
- Kilian Schwartz
- Michel Jouvin
- Marco Cattaneo
- Vincente Innocente
- David Quarrie
- Michele Michelotto

gLite 3.1 will include support for SL4 (in 32bits compatibility mode)

Not a big change but rather the ackowledgment of a new platform.
Have to be done for UI and WN first

X have performed some tests of performance on WN in order to compare between 32 and 64bits and to check the specInt values

Michel Jouvin : current gLite middleware run OK on SL4 nodes we cannot run in native 64bit since it would cause problems with 32bits applications.

Marco Cattaneo : Have talked about virtual machines. 64bits binaries would have to find 64bits machines in order to execute.

David Quarrie ? : In ATLAS, we found that applications compiled in 64bits mode where needing at least twice the memory needed by the same 32bits applications. In which case jobs would have to go to machines with at least 2GB of memory per core.

Federico Carminati : we noticed the same in Alice (AliRoot ?) and it took a long time to reduce the memory needed applications compile in 64bits to a value comparable to the needs of the same 32 bits application.
We recommand 2GB/core however and a large swap space because it is better to have a job swap than to stop it.
Information system :

OS is advertized (should be) by the information system but is it usable ?

That supposes an homogenous farm behind each CE.

Michel Jouvin suggests to use the MAUI feature that permit partitioning of a farm and restrict a specific VO to use a specific partition.

Another way is to provide both 32 and 64bits compiled software and let the job choose at startup.

Remark : when the WN environment does'nt match what the CE advertizes, this gives way to massive failures on the site. Site should always insure that the information system publishes the right info on WN configuration and keep it up to date when changes occur.

It is pointed out that defining sub-clusters within one CE to accomodate different configuration is the right solution.

Question : when will be the first production release of gLite that is compatible with SL4 ?
Answer: not in the next 2 weeks. There are SL4 nodes in the PPS system but we are still waiting for the green light from the experiments.

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JM


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Jean-michel BARBET                    | Tel: +33 (0)2 51 85 84 86
Laboratoire SUBATECH Nantes France    | Fax: +33 (0)2 51 85 84 79
CNRS-IN2P3/Ecole des Mines/Universite | E-Mail: barbet@subatech.in2p3.fr
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