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Comment How are you using the data? (Score 2) 217 217

What clients will you be exporting it to? Linux, OS X, Windows? All three?

What kind of throughput do you need? Is 10 MB/sec enough? 100 MB/sec? 10 GB/sec?

What kind of IO are you doing? Random or sequential? Are you doing mostly reads, mostly writes, or an even mix?

Is it mission critical? If something goes wrong, do you fix it the next day, or do you need access to a tier 3 help desk at 3 am?

We have a couple of petabytes of CMS-HI data stored on a homegrown object filesystem we developed and exported to the compute nodes via FUSE. Reed-Solomon 6+3 for redundancy. No SAN, no fancy hardware, just a bunch of Linux boxes with lots of hard drives.

There is no "one shoe fits all" filesystem, which is part of the reason we use our own. If you have the ability to run it, I'd suggest looking at Ceph. It only supports Linux, but has Reed-Solomon for redundancy (considered it a higher tier of RAID) and good performance if you need it. If you have to add Windows or OS X clients into the mix, you may need to consider NFS, Samba, WebDAV, or (ugh) OpenAFS.

Comment Fail deadly (Score 1) 256 256

Venus? A floating colony in Venus's atmosphere is the very definition of "fail deadly". Anything goes wrong you are dead, whether dead quickly or dead slowly. Plus, given the conditions on Venus, if there ever was an ecology, it has long been reduced to ash. It is also not likely we could terraform Venus (reduce the atmosphere and spin it up) given the resources of the entire solar system to do so.

If I were planning humanity's journey to the stars, I'd go with the moon first, followed by Ceres. Resource rich, low gravity, and far enough out of the Earth's (in the moon's case) and the Sun's (in Ceres' case) gravity well to make exploring other places much easier.

Comment Re:I want my division by zero errors to be errors (Score 4, Interesting) 1067 1067

I agree here. One easy example is computing an average: add up the numbers and divide by N. What if you have no numbers to average and N == 0? That doesn't mean the average is zero, it means you don't have an average. You always have to check for /0 errors, not because you want to keep the program from crashing but because you need to handle all the special cases. It's usually (not always) better to crash to alert you to an un-handled condition than to pretend nothing is wrong.

Should all null pointer exceptions or segfaults be handled quietly in some arbitrary way, in order to make software more "robust?"

Comment Re:Meh (Score 1) 830 830

Nah, the power output tells you if it can support the water heater's current draw while running, but not how much water you can heat. He needed to know the total energy stored in the batteries and the size of the water heater to estimate how many gallons of hot water could be heated and used for the weekend. They were big batteries, and it was enough for some 20 gallons of water or so.

Comment Re:Meh (Score 1) 830 830

There's a grey area here. Celsius is much more nearly metric than Fahrenheit. Most of the time in the engineering world when you're using temperature in calculations it's temperature differences that are important, and for that Celsius is just fine while Fahrenheit is a pain in ... well you first convert to Celsius. Doing thermal calculations entirely in the US customary system is trickier and generally not even taught. A friend was recently going to a vacation home and asked me for help working out the problem of how many gallons of water could be heated by a battery-powered generator operating a water heater. Do you start by converting gallons and Fahrenheit into kg and Celcius, or do you work the other direction and convert Volt-Amperes into Btu/h? That's a rhetorical question.

If you're working in a more academic field than you'll use whatever temperature units are convenient for your purposes. You can't say "... Rankine is better than ..." without being very specific about the area of study.

Similar arguments apply to other kinds of units when thinking about the US "going metric." There isn't only one way to do it, and it doesn't have to be an all-in or all-at-once thing. Considering all of the machine shops and the like, a realistic transition will take decades before we get mostly there. It starts with little things like posting speed limits in Kph (as well as Mph) and selling milk in liters (gallons also labeled). For most units like distance and mass/weight, metric is no more or less "natural" than the US customary system. You do have a merited argument with Fahrenheit vs Celsius, but it's a weak one and lots of folks have become accustomed to C.

If we were ever to make this transition, it might help a tiny bit to de-mystify science. Even just to internalize concepts like force (weight) versus mass. You can't convert pounds to kilograms without assuming some value of g. Pounds convert directly to Newtons, and kilograms convert to slugs.

But on the other hand, if we ever started making metric screw sizes, as one example, then a lot more globalization may start to kick in which is not necessarily a good thing. Maybe it would be, but it's hard to predict accurately. We historically lose manufacturing jobs. Is it advantageous for us to be out of sync with the rest of civilization?

Comment Re:When do we get a real boost over 2013 speeds? (Score 1) 126 126

I do high-performance computing for a living, and Moore's Law has been on its last gasps for a while now.

Until around 2006, the smaller you made a transistor, the faster it could work. This was called Dennard scaling. But once transistors reach a certain size, current leakage and thermal issues prevent you from making the transistors faster.

While they can't drive transistors any faster, smaller processes still allow them to put *more* transistors on a chip. This is why we've gone from single-core to multi-core to multi-core with GPU compute on a die.

Despite all the complaints about "CPU's haven't gotten much faster since Nehalem", they *have* gotten quite a bit faster. You just have to rewrite/optimize/recompile your program to take advantage of multi-core, GPU compute, and SIMD instructions like AVX2.

This is the primary reason programs aren't running much faster than before. Silicon isn't getting any faster, and rewriting programs to scale isn't easy and sometimes isn't worth it so many people don't. Moore's Law no longer results in "free", "easy" speed-ups.

CPU's for the next few years are looking pretty incremental. I'd expect a one-off moderate increase in single-core performance once Intel moves off silicon onto III-V semiconductors (10 or 7 nm?), but past that you will likely be waiting several years for your graphene/nanotube/topological insulator/spintronics overloads to deliver something substantially faster.

Comment Re:faster than light never violates Relativity (Score 1) 226 226

I think you've stated the main argument about stuff moving faster than c. But more abstractly, consider two events that are separated in both space and time, A and B. Let's say A happens first and "causes" B. Maybe A is "someone throws a ball" and B is "someone catches it." Or perhaps A and B could be sending and receiving a communication. In any case if B is outside of the light cone of A, meaning that light or anything slower could not travel from event A to event B, then there is a reference frame in which events A and B happen at the same place. But when you "boost" into this frame of reference, you'll find that B happens before A. Faster-than-light communication implies that effect can precede cause. Maybe that could be true, but regardless that's what we're up against. Part of this is a conceptual difficulty: the nature of space-time is slightly more complex than our intuition allows for. A better intuition might involve a different definition of "now" that is dependent on where you are in space. Your "now" is a little behind mine, and vice-versa. Or something like that.

Comment Re:Is a reduction (Score 1) 89 89

Thanks for this explanation. I was wondering earlier that if the problem was only as bad as "decimation", had scientists considered the various unintended consequences of this treatment? But seeing that the disease is likely anthropogenic, and that it is really wiping out entire populations, it sounds like this treatment can only be a Good Thing.

Comment Customers... (Score 1) 49 49

Software has zero intrinsic value. It doesn't generate a single cent (unless you've written a BitCoin miner, I guess).

Customers, on the other hand, can generate lots of value if they use your software. Customers and the potential for more customers are usually the reason small software firms get acquired for Rockefeller money by the Google's and IBM's of the world (the other reasons are usually acquiring patents or the talent of the development team itself.) The software itself is rarely the target.

Open-sourcing the software increases the odds of someone using their software, either because it's "free", or because having the code in hand keeps them out of trouble if the company were to fold. And even if they're using it for free, it increases the odds that they would be willing to use a paid version at a later date, which is valuable.

And companies pay for reliability, both for necessity and so they have someone to pass the blame to if something fails. Even if someone got a copy of their code and decided to try their own business, are you going to trust them over the original creators when it comes to your job security?

Comment I wonder why... (Score 5, Informative) 289 289

You have to admire the hypocracy of state legislators who argue for "state's rights", who don't care about "city and county rights" to roll out broadband to attract jobs and new people to their area. It's almost like they were hypocrites, ignorant of freshman economics, sold to the highest bidder or something... /Lives in Tennessee, has the same bunch of ignorant cretins passing laws that an 18 year old freshman could easily shoot down as dumb.

Comment Re:Won't save most of the 4000 lives (Score 4, Interesting) 615 615

To give a counterexample, I was driving down a long hill that I have driven daily for 20+ years. At the bottom of the hill, right before it went around a curve, I saw cars hitting their brakes, and knew there was probably a traffic jam around the corner, so I started slowing down.

There was a truck driver pretty far behind me, and he didn't bother slowing down until he came around the curve, saw the traffic jam, locked his brakes, and ran off the road, and blamed me for the accident.

I'm a physics major, so I measured the location of where he locked his brakes, and the point he came to a stop. A little high school algebra showed he was moving 80-85 MPH in a 70 MPH zone when he hit his brakes.

For that reason, I subsequently installed a dashcam in my car. It pays for itself the first time some idiot lies and tries to pin the blame on you.

Comment I want this to be true, but... (Score 5, Insightful) 480 480

I want a non-Newtonian drive as much as any other nerd out there, but it's still more probable that (assuming it works) it uses conventional physics, just in ways they haven't figured out yet.

That said, I think this result is the point where NASA, DOD, Lockheed Martin, Boeing et al should turn on the money spigot for research. There's obviously something going on, even if it's just conventional physics in unexpected ways. And on the odd chance it *is* new physics, the results could change the world.

Comment Re:So let me get this straight (Score 1) 686 686

The claims that Snowden attempted to use the proper channels are disputed by the NSA. I think it's extremely likely that Snowden's version of the story is closer to the truth, but I have to keep in mind that there's some uncertainty there. The outcomes of the leaks are harder to dispute, and I think the net effect was a positive outcome.

And I still recall Obama's speeches that change had to come to Washington, not from it. Heh. But did he live up to his campaign promises any less or any more than other presidents have? I guess good presidents need to work with compromise and internal politics well while in office. I think Nixon was pretty good by that measure.

Comment Don't... (Score 2) 315 315

I'm as geeky as they come. Most of a Ph.D. in theoretical physics, and have spent over a decade working in high-performance computing.

When I was 7 years old, I was wandering through the woods, looking under rocks for creepy crawlies, playing hide-and-seek, and playing baseball with my brother and cousins. Not only did it *not* set me back in anyway, but it is some of my fondest memories of being a child.

Let kids be kids for goodness sake. Take him to a science museum, and let *him* tell *you* what interests you. When I was a kid and hyped about computers, my dad thought computers were a fad only used to play Pac-Man. Not only do I have a good-paying career, but any time dad can't connect to the internet, I get an emergency telephone call.

Let your child steer his future. He's the one who has to live it.

Organic chemistry is the chemistry of carbon compounds. Biochemistry is the study of carbon compounds that crawl. -- Mike Adams

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