Semi Solutions (Jun 08 2009)


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Message boards : Technical News : Semi Solutions (Jun 08 2009)

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Profile Matt Lebofsky
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Message 905295 - Posted: 8 Jun 2009, 21:31:03 UTC

Dan and company are wrapping up their work at Arecibo and heading home today (I think). It was a painful weekend trying to get our data recorder working again (and installing the new SERENDIP V data recorder) but all is well, more or less. We even did some observations of the crab nebula (and its known pulse) which Josh then found in the data using Astropulse, providing a good end-to-end test. We'll send workunits using that data once we get that raw data up here. We ultimately found our SATA drive enclosures were a major part of the headache, and we're planning to replace those with USB enclosures... probably.

It was a painful weekend network-wise - the increased active user load (mixed with the lack of long Astropulse workunits to send out) means a lot more activity on the result table in the database, which means periods of mysql choking. We're adjusting some code to do "dirty reads" which may help conserve resources. For example, the count of the result table to determine the current size of the ready-to-send queue doesn't have to be 100% accurate, so locking the table to do such a query is overkill. We'll see if that works, or helps.

We hope to replace these database servers, or at least the mysql replica, with one of these new Intel servers. They have tons of CPUs and gobs of memory, but the disk controller doesn't work. Actually, that's unclear - we replace the card with one we know works, and that wasn't behaving either. Until we can figure that out we're stuck with what we got.

- Matt
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Richard HaselgroveProject donor
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Message 905308 - Posted: 8 Jun 2009, 22:44:49 UTC - in response to Message 905295.

... the increased active user load ...

Be careful what you wish for ;-)

Thanks for the update, as always.

Profile Andrew Clayton
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Message 905318 - Posted: 8 Jun 2009, 23:14:59 UTC

I wonder if you use, or have thought about using memcached?

http://www.danga.com/memcached/


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Profile Gary CharpentierProject donor
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Message 905319 - Posted: 8 Jun 2009, 23:15:46 UTC

thanks for the update


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Message 905479 - Posted: 9 Jun 2009, 12:21:47 UTC

Good work over the weekend. If I'm reading right, we've got some AP work on the way. Good news for sure.

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Message 905502 - Posted: 9 Jun 2009, 13:47:41 UTC - in response to Message 905318.

Yes, I was going to suggest memcached too - it can cache queries and any other serializable objects, and act as volatile network-shared memory - great for php session handling across multiple webservers, and an essential addition to the LAMP arsenal.

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Message 905848 - Posted: 10 Jun 2009, 17:24:07 UTC

... from the thread title, I expected something involving big rig trucks!... ;-)
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Message boards : Technical News : Semi Solutions (Jun 08 2009)

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