Friday, 23 July 2010

ATLAS pilot analysis stressing LAN

These days a big physics conference is starting in Paris. May be this is the reason behind the ATLAS "I/O storm" analysis jobs we saw yesterday running at PIC... if this is so, I hope the guy sending them got a nice plot to show to the audience.
The two first plots on the left show the last 24h monitoring of the number of jobs in the farm and the total bandwidth in the Storage system, respectively. We see two nice peaks around 17h and 22h which got actually very near to a 4Gbytes/second total bandwidth being read from dCache. As far as I remember we had never seen this before at PIC, so we got another record for our picture album.
Looking at the pools that got the load, we can deduce that it was ATLAS who was generating this load. The good news is that the Storage and LAN systems at PIC coped with the load with no problems. Unfortunately, there is not much more we can learn from this: were these bytes actually generating useful information or were they just the artifact of some suboptimal ROOT caches configuration?

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