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Is LTO Tape On Its Way Out?

Sqr(twg) Re:Tape Culture Fallacy (269 comments)

If the file server uses a file system with checksums, and those checksums are also backed up, then it's a simple matter of reading through the tape and verifying the checksums. You don't need to compare to the original files.

(The probability of a corrupted backup server accidentally creating a correct checksum can be made arbitrarily small. Usually it's something like 2^-256.)

yesterday
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Is LTO Tape On Its Way Out?

Sqr(twg) Re:Shyeah, right. (269 comments)

You might want to look at using ZFS instead of rsync. I switched a while back, and it was definitely worth the initial effort of changing the file system on the server.

With rsync you can get inconsistencies because not all files are backed up at the same instant. ZFS snapshots get around this.

If you modify a large file (say a 100 GB virtual machine), rsync will re-backup the entire file. ZFS will keep track of the part that changed and only copy that.

Also if a file on one of your multiple backups is subtly corrupt, you might not notice. Or even if you do compare the copies, you might not know which one is correct. With ZFS, the entire file system is checksummed and a raid or mirror can heal itself.

yesterday
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I'm most interested in robots that will...

Sqr(twg) Re:Drive me around = I can get drunk (307 comments)

If you don't live in NYC or near another major metro/subway position, and you're too fucking stupid to call a cab instead of driving home drunk, then drinking becomes very dangerous.

FTFY.

about two weeks ago
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What Happens When Nobody Proofreads an Academic Paper

Sqr(twg) Re:MS Office Incompatibility (170 comments)

In that case I'm sure you're doing something like this:

\newif\ifdraft
\drafttrue % or \draftfalse

\ifdraft
(should we cite the fine Gabor paper here?)
\fi

about two weeks ago
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What Happens When Nobody Proofreads an Academic Paper

Sqr(twg) Re:MS Office Incompatibility (170 comments)

The paper in question was most likely not written in LaTeX, or they would have put a percent sign in front of the comment when they first put it in.

about two weeks ago
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There's No Such Thing As a General-Purpose Processor

Sqr(twg) Re:Saturday is Semantics Day (181 comments)

After all each time you add a different type of specialty processor into an environment, you introduce another codebase for the application, another toolchain to learn and another set of communication / OS support issues.

That will be an issue only for the OS and library developers. To the applications developer there will be no noticeable difference. It is already the case that you need to use specialized libraries to get maximum performance on common types of tasks.

For example, if you want to use an FFT on a modern "general purpose" processor, you will get much better performance using a standard library function than you would if you wrote your own. There are so may issues with memory access patterns, core and cache utilization, etc. that you will never have time to figure out if you just want to use the FFT (rather than do research on the algorithm itself.)

If a future CPU gets a built in FFT, then the standard library will be updated, and your application will just run faster. No modification necessary.

about two weeks ago
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Ferguson No-Fly Zone Revealed As Anti-Media Tactic

Sqr(twg) Re:Legal requirements (265 comments)

Keeping the press away is a matter of National Security. That's how it is in every police state.

about three weeks ago
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OneDrive Delivers Unlimited Cloud Storage To Office 365 Subscribers

Sqr(twg) Re:Who cares (145 comments)

I used to hang out in a swedish photography/videography forum. Bandwidth is cheap in Sweden, so a lot of these guys were on 100+ Mbit connections and liked to keep a backup in the cloud. Whenever a new "unlimited" storage service came around they'd hop on and upload tens of terabytes of photos/videos. (None of wich could be de-duplicated, since it was all original work.)

Inevitably, the storage service would update its TOS within a year, or go bankrupt.

about a month ago
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Ask Slashdot: How Do I Make a High-Spec PC Waterproof?

Sqr(twg) Re:Water cooled! (202 comments)

This is currently modded "funny", but is actually a very good solution to the problem. With water-cooling, all electrical components, except the radiator fan, can be in an air-tight enclosure. Then get an IP rated fan, or a larger, fanless radiator.

about 1 month ago
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Michigan Latest State To Ban Direct Tesla Sales

Sqr(twg) Re:Great Job (256 comments)

On the contrary: This is the ultimate free market. Even the politicians are for sale. All Tesla motors need to do is raise some money, buy half the legislature, and ban the sale of non-electric cars. A kickstarter campaign would probably do it.

about a month ago
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32 Cities Want To Challenge Big Telecom, Build Their Own Gigabit Networks

Sqr(twg) Re:Hey Verizon, can you hear us NOW! (175 comments)

It's interesting how it is always "Socialism vs Capitalism", with most people divided into two camps, and very few saying that one or the other migh be better depending on circumstances.

I like capitalism when there's a natural way that businesses can compete. For example, adjacent coffee shops might compete on a number of parameters like price, quality, speed of service, etc. It is possible to establish a new coffee shop in an area that already has one, if you can compete on at least one of theres parameters.

I like socialism when there is no way that cometition will work. For example ISP:s provide basically identical service, so they can only compete on price and marketing. Marketing is bullshit, so rational people will pick the one with the lowest price. This means that with one ISP in place, the other ISP:s have no incentive to build infrastructure in the same area, because competition would drive prices down to where they can't recover the initial investment. The single ISP therefore gets a monopoly. It is preferrable that the monopoly is owned by the state.

about a month ago
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The Physics of Why Cold Fusion Isn't Real

Sqr(twg) Re:Why Cold Fusion (or something like it) Is Real (350 comments)

The most likely answer to this riddle is that all of the so called researchers are complicit.

Never attribute to malice what can adequately be explained by incompetence.

The researchers did make a measurement that reveals the hidden circuit. They just didn't realize it themselves. (They measured currents in order to estimate heat loss in the cables.) Details here.

about a month ago
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The Physics of Why Cold Fusion Isn't Real

Sqr(twg) Re:Why Cold Fusion (or something like it) Is Real (350 comments)

The latest report on Rossi's device actually contains clear evidence that the experimental set-up has been tampered with. On page 14 it says:

  "Measurements performed during the dummy run with the PCE and ammeter clamps allowed us to measure an average current, for each of the three C_1 cables, of I_1 = 19.7A, and, for each C_2 cable, a current of I_1/2 = I_2 = 9.85 A."

Here, I_1 and I_2 are the line and phase currents of a set of delta-connected resistive load inside the "reactor". The ratio between these currents should therefore be sqrt(3) (approximately 1.73). Since the measured ratio is 2, the curcuit diagram cannot correspond to reality. The reactor probably contains two separate sets of star-connected resistors instead. By feeding current to the second set out of phase with the first, like I suggested in a previous slashdot comment, the current clamps are fooled into giving a too low measurement.

This document (in Swedish) explains it all in detail.

The fact that these measurements were performed and reported also implies that the authors of the report were not part of the fraud. Rossi simply fooled them all.

about a month ago
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Independent Researchers Test Rossi's Alleged Cold Fusion Device For 32 Days

Sqr(twg) Re:He tried patenting it... (986 comments)

Of course the wiring diagram doesn't show any doubled cables. My point is that one of the cables might contain two conductors without the authors being aware of it.

There is no logical explanation for the six cables going into the "reactor". Three cables would be enough for a star configuration. If you add the requirement that the resistors must be connected in a delta configuration, then four cables would be enough.

The only reason I can think of for the extra cables is that they are part of a hidden circuit.

about a month ago
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Tiny Wireless Device Offers Tor Anonymity

Sqr(twg) Re:I wonder how much we can trust it (68 comments)

The three-letter agencies don't need to insert a backdoor. All they need to do is operate a bunch of Tor exit nodes.

As soon as you use Tor for everyday activities you are effectively not anonymous anymore.

Example: You set up the WiFi router and start doing your secret stuff. The bad guys have no idea who's behind the connection.
Then the jogging app on your iPhone connects over the same Tor tunnel. It opens an unencrypted connection to a "share my run" server, and now the bad guys know your email address, weight, and the GPS coordinates of the route you ran this morning. They don't even have to tap your or the server's connection. They get the information directly from their own exit node. (I.e. easier than if you had not been running Tor. Anyone can do this. Not just the three-letter agencies.)

Want anonymity? Install the Tor Browser. Then only use it for the anonymous stuff. Never visit any of the sites you ordinarily frequent.

about a month and a half ago
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Independent Researchers Test Rossi's Alleged Cold Fusion Device For 32 Days

Sqr(twg) Re:He tried patenting it... (986 comments)

Here's how I think it was done:

Looking at Figure 4 in the report, we see that input power (current) was measured independently in two places. PCE 830 A meaures current going in to the control system, and PCE 830 B measures current going from the control system to the E-Cat. (Thease mesurements are in agreement, and both show less than 1 kW going in while other measurements show more than 2 kW of heat being generated.)

The placements both PCE 830 units are strange. PCE 830 A doesn't sit directly on the 380 V input from the lab, but instead sits between the control system and a "switch" (dentoted "SW"). Similarly, PCE 830 B doesn't sit directly on the three cables going into the E-Cat. Instead it sits between the control system and "connection boxes" (denoted "C").

Anybody who has used a current clamp knows that you must measure around a single conductor. If you measure around two conductors you get the sum, which can be zero even when a large amount of power is tranferred through the cable. So if any of the wires going from the control system to the "switch" contains two conductors instead of just one, then it is possible to feed current through without it regestering on PCE 830 A. Similarly, if any of the cables going from the control system to a "connection box" contains two conductors, it is possible to send power through without it registering on PCE 830 B. (The cables that come after the connection boxes would be much harder to fake, because they connect to high-temperature Inconel conductors at the end.)

So my guess is that the "control system" contains two separate units. One works exactly as advertised. The other is powered using an extra conductor in one of the cables to the "switch". Its ouput corrent is similarly hidden using extra conductors in the wires coning to the connection boxes.

This second unit is designed to only output power under specific circumstances. (Which is why Rossi himself was controling the experiment.) For example, I found it strange that the temperature of the "dummy" reactor was always much lower than the temperature of the "working" reactor. Maybe that is the trigger.

about a month and a half ago
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Independent Researchers Test Rossi's Alleged Cold Fusion Device For 32 Days

Sqr(twg) Re:He tried patenting it... (986 comments)

NONE of those explain the change in isotope species described in the article.

As I recall, an earlier version of the device also produced nickel, but in the naturally occuring isotope mix. The fact that it didn't proudce the correct isotope was the main objection that the Swedish researchers had then. Now it suddenly produces Ni62, so apparently, this guy has not only discovered one, but two different cold fusion reactions...

At this point, the test for fraud is to determine if the calculated energy released is congruent with the change in the mass energy potential of the sample before and after the experiment.

That change in mass is far too small to measure. The random part of the change in mass due to sublimation (atoms leaving the surface when the device is hot) is much larger than the change in mass-energy.

about a month and a half ago
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Past Measurements May Have Missed Massive Ocean Warming

Sqr(twg) Re:What happens to that heat? (423 comments)

I did not chose the years. This was a quick copy-paste from Wikipedia. I suppose they picked the intervals so that the number of observations in each bin would be about 20, which implies a standard deviation uncertainty of about 4.5 hurricanes in each interval.

But since you didn't like that table, here's one just for you:

1851–1900 13 0.26
1901–1950 29 0.58
1951–2000 46 0.92

(Each of the above intervals is 50 years, not 49. I haven't found any statistics on the correlation between being a climate change skeptic and being unable to do simple math, but I'm sure it would be interesting.)

Now, if you really wanted to raise a valid objection, you would point out that weather satellites did not exist until the 1960:s, and that the number of severe hurricanes might have been underestimated prior to that.

about 1 month ago
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Past Measurements May Have Missed Massive Ocean Warming

Sqr(twg) Re:What happens to that heat? (423 comments)

Also, these so-called "scientists" claim that there will be "winter" a few months from now, but the weather today is actually warmer than it was yesterday, so I'm scratching my head...

about 1 month ago
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Past Measurements May Have Missed Massive Ocean Warming

Sqr(twg) Re:What happens to that heat? (423 comments)

And just around the same time we've had a recent minimum of severe hurricanes.

By which you mean that we had no category five hurricane last year? That's just a consequence of the fact that there is less than one per year on average, and the number must be integer. (If you do the count per decade, then 2000-2009 had the highest number (8) of category five hurricanes in recorded history, but this number is still too small to draw any statistically significant conclusions from.)

There is more information in the data on category four hurricanes. I found this table of category 4 hurricane statistics on wikipedia

Period Number Number per year
1851–1900 13 0.26
1901–1950 29 0.58
1951–1975 22 0.88
1976–2000 24 0.96
2001–2012 19 1.6

about 1 month ago

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