En mag ik ook even uw aandacht vestigen op het volgende topic?
dank u
Inhoudsopgave Seti@Home hitparades week 15
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Wat is Seti@Home ?
Wat is SETI@home?
SETI@home is de naam van een wetenschappelijk experiment dat computers die via het internet met elkaar verbonden zijn, inzet om buitenaardse intelligentie op te sporen. U kunt hieraan deelnemen middels een gratis computerprogramma dat radiotelescoop-data download en analyseert.
NIEUWS UPDATE
7 Apr 2011 | 22:42:01 UTC
Turns out one of the inputs to our data recorder got messed up. I don't have the details, but this only happened recently - we haven't yet gotten the raw data from Arecibo to split into workunits, etc. And the problem will be fixed soon if not already. The key now is to add some smarts to our scripts to avoid splitting the particular beam on that particular day or so. I guess this is a feature we've been meaning to add, and now we have a reason.
I've been messing a lot with gprof the past couple of days trying to find the subroutines causing the greatest slowdowns in our final analysis code. This actually wasn't getting me very far - I just now had to resort to some fprintf's with microsecond-level timestamps. No big news - we're database i/o constrained but now I have some numbers. We're brainstorming ideas about how to keep only the stuff we need in memory (as opposed to whole tables or indexes). Also I've been getting back to work cleaning up the NTPCkr pages for ultimate public consumption (and ultimately public assistance in helping us find and score detections). Slow, steady progress.
Otherwise all systems are go - bulking up the data pipeline before the weekend, queues are draining, etc. The mysql replica seems to be chugging along just fine. We'll see how it goes through the weekend before we call that project done.
- Matt
5 Apr 2011 | 22:43:45 UTC
Happy Tuesday! We had our usual outage today (mysql cleanup/backup). The replica mysql server is still having issues. Over the weekend while it was catching up after being rebuilt it hit some corrupted relay log data. This is a bit troublesome - either the logs were corrputed on carolyn (the master) or they got corrupted during to transfer to the replica, or there are still fibre channel issues on this system causing random storage corruption (even after swapping out the entire disk cage, cable, and gbic). I'm rebuilding the replica yet again (with today's backup) and we'll go from there...
Some good news: The entire lab recently upgraded to a gigabit connection to the rest of the campus (and to the world). Actually that was months ago. We weren't seeing much help from this for some reason. Well today we found the bottleneck (one 100Mbit switch) that was constraining the traffic from our server closet. Yay! So now the web site is seeing 1000Mbit to the world instead of a meager 100Mbit. Does it seem snappier? Even more important is our raw data transfers to the offsite archives are vastly sped up, which means less opportunities for the data pipeline to get jammed (and therefore running low on raw data to split). Note this doesn't change our 100MBit limit through Hurricane Electric, which handles are result uploads/workunit downloads. We need to buy some hardware to make that happen, but we may very well eventually move our traffic onto the SSL LAN - this is a political problem more than a technical one at this point.
Over the weekend we had some web servers croak here and there, affecting the home page, workunit downloads, and scheduling. We think this was all due to removing ptolemy from our server mix (the system is powered off and its name and IP address are back in the general pool). Many machines/scripts still have references to ptolemy (or files on ptolemy). We did our best to clean this up before shutting it off, but we knew there would be some minor aches and pains. In this case, a generic web log rotation script was having fits and not killing/restarting apache very well.
- Matt
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APClll op 16-04-2011 23:37
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Welkom Colin 
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