Beta Bits (May 06 2009)


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Message boards : Technical News : Beta Bits (May 06 2009)

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Profile Matt Lebofsky
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Message 892076 - Posted: 6 May 2009, 20:39:57 UTC

We recovered fairly well after the outage, despite all the minor annoyances as of late. We still have to resync the beta database on the replica - turns out there was corruption in those tables that didn't get noticed until after we brought everything up again. Well, not so much corruption as a bit somewhere that told mysql to not bother dumping the beta database because it thinks there's corruption. So when I tried to rebuild the replica with the dump (when the beta project was back on line) and found the dump was zero length, I issued the proper repair statement and mysql responded "0 errors" but then was able to dump everything. Whatever. It's fine for now - and it is just the beta database, so we'll clean that up next week.

As for fears of running out of data while we're waiting for the data recorder to get fixed: we still have plenty on line, and a few drives on the shelf full of data sent up from Arecibo as part of the last shipment they made before the SATA card went kaput. Plus we have a bunch (how much? not sure, but a lot) of data in our archives at HPSS which we haven't processed yet. So we're good for now, and maybe even a month or two.

As for those network graphs talked about in the previous thread: that particular graph is for a router down on campus which handles the tunneled traffic to/from our lab and destined for our router at the PAIX (where we hook up with our ISP bandwidth). So yeah, green shows "incoming" from the lab, which is what we see as "outgoing" i.e. downloads. And vice versa for the uploads. Of course, there's a tiny tiny bit of noise due to scheduler traffic which also goes over that link.

- Matt

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Message 892092 - Posted: 6 May 2009, 21:47:08 UTC - in response to Message 892076.
Last modified: 6 May 2009, 21:51:06 UTC

Thank you for answering my questions from yesterday's news item & the update Matt. Do you keep a large amount of data at HPSS in the event that a piece of hardware goes kaput, or Is it because the data is collected to fast for us to process?
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Message 892202 - Posted: 7 May 2009, 5:28:57 UTC - in response to Message 892092.

Thank you for answering my questions from yesterday's news item & the update Matt. Do you keep a large amount of data at HPSS in the event that a piece of hardware goes kaput, or Is it because the data is collected to fast for us to process?

Well before the data storage servers were donated a few months ago, there was very limited storage space in the lab, and the disks were coming from Arecibo faster than we could split and process them, and there was very little disk space to handle the 50gb "tapes". Now that there are many terabytes of storage space, many tapes can be stored locally on the servers.

So now with no new tapes coming in, and the splitters are still chewing away at the local tapes, when local space frees up, "rainy day" tapes will be pulled from HPSS to keep the flow going.

At least, that's my understanding of it all.
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Message boards : Technical News : Beta Bits (May 06 2009)

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