Storing CERN's Search for God (Particles) 154
Chris Lindquist writes "Think your storage headaches are big? When it goes live in 2008, CERN's ALICE experiment will use 500 optical fiber links to feed particle collision data to hundreds of PCs at a rate of 1GB/second, every second, for a month. 'During this one month, we need a huge disk buffer,' says Pierre Vande Vyvre, CERN's project leader for data acquisition. One might call that an understatement. CIO.com's story has more details about the project and the SAN tasked with catching the flood of data."
News for Nerds! (Score:5, Insightful)
Um no...it's a product placement for Quantum (Score:5, Informative)
Re:Um no...it's a product placement for Quantum (Score:5, Funny)
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Imagine being able to zoom in on some porn and seeing the actual DNA of the actress(es)...
"Too much information" (Score:3)
well if no one else is going to say it (Score:3, Informative)
"Imagine how deep the personality problems must run in a person who gets all hot because of someone's DNA sequences!"
You must be new here.
God Particles (Score:3, Funny)
Re:Um no...it's a product placement for Quantum (Score:5, Insightful)
You may think of it as product placement, but I use it. I even provide the occasional blog entry [blogspot.com] on it on Advanced Topics. I sat through a RedHat performance tuning class that was quite excellent. But when they came to the part about ext3 and tuning it, well, let's face it - ext3 just isn't going to scale. I started with Veritas' Filesystem which is pretty nice. If you're a small-time admin, then you never get beyond a local, 4U disk array. Once your group spends more than US$2million on servers though, it's obvious what the problem is: Storage - The Final Frontier. SAN and clustered filesystems allow a level of scalability completely unheard of before.
They also completely left out anything but a tagline of their multi-tiered solution. I wish they'd talked more about how CERN supports 500Gbit per second aggregate throughput to their disks (at least they implied that). 50GB/sec (or so) is probably the toughest I/O problem you've ever dealt with, or will deal with for a long time. Whose RAID controllers did they use? Did they focus on speed (ASIC and ISL minimization), availability (redundant fabrics), or both? Did each node get dual 4Gb links or just one?
If this had been an advertisement, they would have discussed some 3.0 features like LAN clients.
So, in short, it's easy to say it sounds like an advertisement. Quite possibly, Quantum (formerly ADIC) coerced them into getting the piece written. But if this had been an advertisement, there is so much more that is going on under the hood that would have been said. Large, fast, distributed filesystems are non-trivial and take an extreme amount of engineering and testing. StorNext really is good at what they claim to do.
If you want to read about some of the drawbacks though, I yak about them on my blog [blogspot.com]. Sorry for the plug.
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400 is nowhere near the order of magnitude different from 500 as your choice of units imply.
Re:News for Nerds! (Score:4, Interesting)
Interesting article.
Many years ago when the SSC (Superconducting Super Collider) was still being built in Texas, I went to an HP users group meeting as I was working primarily with HP-3000 systems at the time. The fellow addressing the meeting was the head of the physics department at the SSC. It was a really neat presentation, in which he described a similar, though orders of magnitude smaller data storage requirement, though he was talking terabytes of data per month IIRC. At the time, they were planning on using two arrays of 40 workstation computers to handle the load. This would have been fairly early loosely coupled setup similar to a Beowulf cluster.
After the presentation I went up to him and told him that all I wanted to do is sell him mag-tapes.
These types of experiments evidently produce tons of data. I wonder if the processing could be parcelled out like Stanford's Folding@Home or SETI to speed up data correlations.
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It's a really neat system that makes the geek in me happy =)
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i remember when i was under 18 i used to go to alot of places i wasnt allowed in just to check things out. i wasnt a malicious kid that would run around breaking things for fun, i just loved seeing various things that most people never see or think about, especially feats of engineering.
when i turned 18 i looked back and was
Re:News for Nerds! (Score:5, Interesting)
Re:News for Nerds! (Score:5, Informative)
Milosz [hulboj.org]
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Offtopic beyond comprehension [Re:News for Nerds!] (Score:2)
Re:Offtopic beyond comprehension [Re:News for Nerd (Score:2)
http://208.69.34.230/search?ie=UTF-8&oe=UTF-8&sour ceid=navclient&gfns=1&q=1.21+gigawatts+%2F+88+mile s+per+hour [208.69.34.230]
Re:Offtopic beyond comprehension [Re:News for Nerd (Score:2)
It's force.
P/v
= (W/t) / (s/t)
= (W/s)
W = Fs, therefore P / v = W / s = F.
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PC's? (Score:1)
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Not Informative (Score:2)
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Ok, who put California Games x 1000000000000000000000000000000000000000000000000
Re:PC's? (Score:5, Informative)
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Just 'LOAD' and press play?
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If Only... (Score:4, Funny)
there I said it, let's move on now.
The mere thought of that much bandwidth... (Score:1, Offtopic)
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Gigabits or Bytes? (Score:2)
It's too late to do math.
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"In total, the four experiments will generate petabytes of data."
Divide at least 1 PB by four and you get 256 TB, I was close with 328 TB, so it must be Gigabits.
30 racks, $1.8M in disks (Score:4, Informative)
Assuming a non-RAID 3x-replication tech solution (what Google do in their datacenters), using 500-GB disks (best $/GB ratio), they would need about 16 thousands disks:
Which would cost about $1.8M (disks alone):
15552 (disk) * 110 ($/disk) = $1710720
Packed in high-density chassis (48 disks in 4U, or 12 disks per rack unit), they could store this amount of data in about 30 racks:
15552 (disk) / 12 (disk/rack unit) / 42 (rack unit/rack) = 30.9 racks
Now for various reasons (vendors influence, inexperienced consultants, my experience in the IT world in general, etc), I have a feeling they are going to end up with a solution unnecessarily complex, much more expensive, and hard to maintain and expand... Damn, I would love to be this project leader !
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The LHC went with a tape-based, distributed storage system. Seven T1 sites around the world keep the data on tape (one copy at CERN, another copy at a T1 site). They do reconstruction of the raw data, and write the reconstructed data on disk. They then distribute the reco data to a T2 site, which has a large amount of disk-only space (like you suggest). The individual physicist does
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If they were smart, they'd choose February. They could save ~172800 seconds and therefore some disk space!
A rough calculation on disk size (Score:2, Interesting)
Wow.
Something like 3000 of the current ITB drives.
How long until Exabyte level storage is required for some project or another?
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FTL (Score:3, Funny)
Next up ludicrous speed [wikipedia.org]!!! Better fasten your seat belts...
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Actually it would be better to say "ridiculous energies" because the speed of the protons in the LHC will barely be any faster than those in the Tevatron...but the energy is seven times larger thanks to relativity.
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Thousands of disk drives. (Score:3, Funny)
Re:Thousands of disk drives. (Score:5, Informative)
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You ought to have Google store that data for you. Seriously.
Google has collaborated on other scientific projects before, and one in particular has many of the same needs as the LHC, the LSST [lsst.org]. Of course, it doesn't hurt that one of the primary backers of the LSST is an ex-Google exec.
I'm confident that Google is capable of dealing with large data stores, even those on a multi-PB scale, with reliability and redundancy.
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Just because the data goes through fiber doesn't mean the disks have to be FC disks. Actually that's usually a bad idea, as the physical operations of the HDD (moving heads around and such) limit the rate at which the disk can actually accept data to much less than FC speeds.
I have a couple local RAID boxes here and I feed data into them through 4Gb fiber channel, but the box just consists of 16 run-off-the-mill SATA drives in a RAID5 config (yielding 14 data disks (plus 1 parity plus 1 hot spare) times 7
Where's the problem? (Score:2)
A big disk (Seagate ST3750640AS) is 750GB.
324,000 GB / 750GB/disk = 3,456 disk.
At AUD467 per disk this will cost AUD1,613,952 (plus computers+net). Even cheaper if you allow for the fact these are retail
prices for wholesale quantities. Let's take the startup current of 2A@12V as the worst case power
consumption and we end up with a maximum power of 83kW. That's less than 35 domestic heaters (2.4kW ea).
Okay, it's not trivial s
Ah, engineers. (Score:2)
Fun problem (Score:2, Insightful)
200 computer breaks the 1GB chink into more manageable 5MB/Sec chinks of data, but then they still need to handle the metadata that figures out how to put it all back together. On top of this they'll need to have some redundancy in case of data loss, and how the load is redistributed if a machine croaks.
These are good problems, it would be a fun system to work on.
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Not So Huge (Score:5, Informative)
SDI is how the movie guys move their digital stuff around. A higher end digital camera will capture at 2x HD SDI for a 2K res, 4:4:4 colour space. A few of em' and you got your 1GB/s easy. Spools onto godlike RAID arrays.
Get em' to call up Warner Bros if they have problems.
It's not that much, really (Score:2)
E-Mail it to Google (Score:3, Funny)
CERN DAQ is generally impressive (Score:5, Interesting)
Right now, the average event size for ATLAS is 1.6 MByte and the system is designed to keep around 200 events per second, or roughly 300 MByte. This isn't much of course, but you have to consider that the bunch crossing rate (i.e. the rate at which bunches of protons will collide and generate events) is 40 MHz.
So you have to design a system that boils this rate from 40 MHz down to 200 Hz and only keeps the interesting parts, while also buffering all the data in the meantime. For this reason, the first trigger level is entirely implemented in hardware right in the detector and reduces the rate down to 75 KHz with a latency of 2.5 s. The rest of the trigger works on clusters using Linux computers and has a latency of o(1s).
Better yet... (Score:2, Interesting)
Not really that much storage bandwidth... (Score:2, Insightful)
Basically, 4k film, at a resolution of 4096x3112, requires approximately 50MB per frame @ 24 fps. That comes out to about 1.22GBps, and maninuplating the data doubles it to 2.44GBps. The systems[PDF] [filmlight.ltd.uk] that Baselight sells run 8 nodes and 16 process
Choice of filesystem (Score:2)
ALICE is not Higgs Hunting (Score:3, Informative)
The CIO article is incomplete (Score:2, Informative)
OK, we got a half way overview of CERN's decision, with some bold statements of questionable validity. I am submitting the criticism purely on the grounds of being really interested in large data storage, I don't work for any large storage vendor, but I am an architect of storage systems.
First of all, with the statement "and it's (StorNext) completely vendor independent": Lot's of other solutions provide flexibility about choosing the hardware vendor from a theoretical perspective. The theory says that if
Hang on... (Score:2)
If I were to write up my house network I could say 'network switches feed data to several computers at 1Gbit per second' - this would be true if I only use it for web browsing - doesn't mean I'm saturating my bandwidth.
Backup options (Score:5, Funny)
- Printed hardcopy. Many authorities recommend this as you do not need to worry about changes in data formats over time. For exact calculation, we would need to know the font they were planning to use and the character encoding. However, let's take a working assumption that they can cram 10KB of data onto an A4 sheet. That implies 259,200,000,000,000 pages. They will probably not want to use an inkjet printer if they use this solution and may, indeed, choose to acquire multiple printers and split the load. A single printer at 10 ppm would take approximately 50,000 years to complete the backup. On 70gm paper, it would weigh a little over two million tons. At any rate, this would certainly produce reams of output.
- Diskettes. This was good enough for nearly everyone 15 years ago. It is curious that such a tried and trusted technique is no longer in fashion. I assume regular 3.5" 1.44MB diskettes, generally recognised as easier to handle than 5.25". We shall need around 1,800,000,000 diskettes. One drawback is the person changing the diskettes as each one filled up might become a little bored after a while. On the positive side, the backup will be quite a lot faster than the printed solution. Assuming about one diskette per minute, inclusive of changing disks, the backup could be complete in less than 3,500 years.
- Now considered somewhat old fashioned, punch cards were once a mainstay of every programmer's personal backups. Like printed hardcopy, anyone familiar with the character encoding used, could read the data without needing any access to a computer. If we assume 80 column cards, we would need 32,400,000,000,000 cards. I would be somewhat concerned about the problem of getting this stack of cards back in the correct order if I dropped it. With a weight of about 30 million tons and stretching perhaps 6 million miles end to end, handling certainly would be challenging and an accident very possible.
- Paper (punched) tape was the only alternative on the first computer I used, a basic early model Elliott 803 without the optional magnetic tape. If I recall correctly, you could manage about 10 characters per inch, so you would need a paper tape over 4,000,000,000 miles long. Hmmm, that would be silly. The other solutions are clearly better.
I am sure other options will be considered, but I just wanted to bring these up in case CERN had failed to consider themRe: (Score:2)
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Of course, the tower of floppies for each day would be 151km high...
No, I don't know what that is in football fields.
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Re:Pseudo-Dupe? (Score:4, Funny)
The other article appeared because it knew this one would be submitted later in the future.
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* sigh *
When society finally moves past this silly "god" idea, as it has with a lot of other silly superstitions, we will all be _so_ much better off. I really don't mean this in a disrespectful way (i'm perfectly willing to be your friend, even if we disagree on the "god" thing, and I can respect people for a lot of reasons, even if we differ on matters of religion), but it's really what I think / feel. It's done waaaaay too much harm, and the sooner we jettison it, the better.
Regards,
John, your friendly
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Finding God (Score:4, Funny)
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They'd have proven God exists, AND done so using scientific methods. It'd be the death blow for half of the worst organisations in the world.
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Thanks to all the posters for the witty responses.
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Geez, haven't you been paying any attention to physics for the last fifty years? Just as atoms (or protons, neutrons and electrons) can be used to create any kind of matter, so the God particle can be used to create any kind of god. Once they isolate the God particle, they'll be able to create a god who actually likes science. Or create a god who isn't always short
A correct use of the word "catch". (Score:5, Insightful)
From the linked article [cio.com]: "... the team is using Quantum's StorNext software as its file system..."
Question: Did a Slashdot editor get paid directly for running an advertisement disguised as an article? Or was someone in Slashdot's parent company paid "under the table"? Or did the parent company get paid?
Anyone wanting to read a real article from 2005 about CERN's data handling, data storage, and data processing can download this PDF file: Grid Computing: The European Data Grid Project [web.cern.ch].
Real articles begin this way: "The computing challenges for LHC are: * the massive computational capacity required for analysis of the data and * the volume of data to be processed."
Advertisements begin by talking about God and murder, this way (from the article linked by Slashdot): "CERN's Search for God (Particles)..."
and "Maybe you last read about CERN (the European Organization for Nuclear Research) and its massive particle accelerators in Angels & Demons by Dan Brown of The Da Vinci Code fame. In that book, the lead character travels to the cavernous research institute on the border of France and Switzerland to help investigate a murder."
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Just two points which may seem to ignore:
Firstly, the Data is of no use if it just sits on some tape/disk drives at cern, because it has to be analyzed as well if you actually want to find something. Back when the whole thing started, it was deemed to expensive to build a central analysis facility at CERN, so the LHC Community Grid was created, some ~100 datacenters around the world with lots (>20k) of CPUs and lots of diskspace.
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No, I believe the word was catching. As in:
They're throwing all this data at me and I gotta catch it.
"Catching a flood"? (Score:2)
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Try 5,000 years ago (Score:3, Informative)
"Caching a flood of data" (Score:2)
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No. No, my friend; you do not grasp the scale of this project.