[Go-essp-tech] Progress and Problems with P2P

[Sébastien Denvil]

Hi Jennifer, all

see below:

Le 01/02/2012 17:08, Jennifer Adams a écrit :
> Hi, Everyone --
> I have been working with Luca and Gavin and Estani on testing the P2P system. I'm happy to report that the many significant parts of my workflow for downloading data can now be fully automated:
> 1. Search for available data sets that meet my desired requirements (e.g. decadal1980/atmos/mon/Amon, all models, all members, selected variables)
> 2. Compare search results to a list of what I've already got
> 3. Build script to download and run wget scripts for datasets I still need
> All this using shell scripts and without touching a browser!
>
> There are still a few wrinkles, however. The worst of these is that not all data nodes are authenticating certificates properly.
>
> These data nodes are working:
> bmbf-ipcc-ar5.dkrz.de
> cmip-dn.badc.rl.ac.uk
> dias-esg-nd.tkl.iis.u-tokyo.ac.jp
> esgdata.gfdl.noaa.gov
> esg.cnrm-game-meteo.fr
> norstore-trd-bio1.hpc.ntnu.no
> pcmdi11.llnl.gov
> vesg.ipsl.fr

To help you diagnose the source of your PKI issues :

> These data nodes are not:
> dap.cccma.uvic.ca

It works for us as I write. PCMDI openid if it matters.

> esg.nccs.nasa.gov

We have never been able to download from there using PKI.

> bcccsm.cma.gov.cn

We have been able to download from there using PKI recently.

> tds.ucar.edu

We have been able to download from there using PKI recently.

> pcmdi9.llnl.gov

We used pcmdi3 up to know (it worked), will give a try to pcmdi9

> esg-datanode.jpl.nasa.gov

Did not tried yet.

>
> P2P wget scripts to download data from the second set of data nodes always fail completely (for me, a "pure client" user). I know that Luca and Gavin and Estani are working to fix these problems, but here's some encouragement to the data node administrators to help them resolve this issue. Wgets that rely on the quickly-expiring authorization tokens ought to be deprecated as soon as possible -- they are the biggest, most irritating source of errors in the whole system (my opinion only).
>
> The second problem is that the wget scripts don't often succeed in getting all the files they are configured to grab. Of the 64 scripts that I ran this morning, 55 were incomplete (that's 86%). The errors in log files are all "ERROR 403: Forbidden." I was running the 64 scripts at one time, but each one was grabbing its list of files in order -- I am not parallelizing the wgets in the way that some other users have described. When I rerun the wget scripts from the incomplete runs, some of them finish the job on the 2nd try, others will take as many as 8 tries before all the files are in.
>
> These are the data nodes that are not allowing me to complete the download (for the decadal1980 example mentioned above).
> esg.cnrm-game-meteo.fr
> vesg.ipsl.fr
> dias-esg-nd.tkl.iis.u-tokyo.ac.jp
> cmip-dn.badc.rl.ac.uk
> bmbf-ipcc-ar5.dkrz.de

I notice that those node seems to be far away from your home location.
May I suggest you to give those options to wget ; from our experiences 
with synchro-data they appear to improve substantially the success rate :
wget --timeout=20 --tries=10

A lot has been said about this issue. Difficult to attribute properly 
the responsibility of those failure to such or such components/parties. 
Give a try to the parameter above.

If you send me the IP adress you used we could investigate the 
vesg.ipsl.fr case.

> I suspect there are some throttling settings in place to limit the number of wgets that a data node will allow at any particular time. I think my use of the data nodes is reasonable, and these throttles are set too high.

It's quiet hard to set this up properly using a tomcat free version. 
Some commercial tomcat version offers easiest way to achieve that. Up to 
know (on our node : vesg.ipsl.fr) we haven't done anything specific 
regarding that.

regards.
Sébastien
> The dreaded "Forbidden" errors may be related to another problem, but are still a nuisance no matter what the reason. YAO (Yet Another Obstacle). Please put this on the high priority list of things to fix, right behind the certificate authentication issue.
>
> Respectfully submitted,
> Jennifer
>
>
>
>
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-- 
Sébastien Denvil
IPSL, Pôle de modélisation du climat
UPMC, Case 101, 4 place Jussieu,
75252 Paris Cedex 5

Tour 45-55 2ème étage Bureau 209
Tel: 33 1 44 27 21 10
Fax: 33 1 44 27 39 02


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