2142 posts • joined 10 Jun 2009
Re: MTBF of SSD - MLC, SLC, TLC ...
SLC is OK. It's rated at a million-plus write cycles. 1M x 256G drive size / 1G bytes per second = 256M seconds to wear it out. Given a decent wear-levelling technology, that's about eight years at a rate somewhat in excess of current drive tech.
Another thing is that flash blocks fail on write. Provided what has been written is tested while it can still be re-written, data-reliability should not be compromised even when a significant fraction of the device has failed.
If it's cache you're using it for, then even a total bricking doesn't hurt much. Just toss it. Plug a new one in and let the cache refill.
Re: @Nigel 11
The gyro I was thinking of wasn't in an evacuated enclosure. Old tech! If you don't like that example I could have said that a Dremmel tool can do 35K rpm.
A disk couldn't work in vacuum because the head uses aerodynamic effects to "fly" just above the rotating disk. I read once that they could make them go a lot faster if they were fillled with Helium rather than air. The seal is probably the problem on that front.
Anyway, the velocity at the rim of a 2.5" disk doing 22K rpm is no greater than that at the rim of a 3.5" disk doing 15K rpm. You can buy the latter, so why not the former?
Re: "Daddy, daddy, what's a floppy disk?"
I imagine that an SSD will still be called the hard drive. The distinction being made was and is between that and removeable-media drives. Though perhaps the time isn't so far away when it won't be a separately replaceable module for much longer, it'll be soldered onto the motherboard.
Re: 15K growing or 2.5" growing?
The physics of fast drives is better if you keep them small. In particular it's much easier to seek faster if the heads have to span only the width of a 2.5" disk compared to a 3.5" disk. The arms on which the heads are mounted are smaller and so their moment of inertia decreases.
I'm slightly surprised that we haven't seen even faster 2.5" drives yet. They can do 15K 3.5" so 22K 2.5" should be straightforward. Stress on the disk no greater, ditto velocity of the disk at its edge so head-flight physics the same. A bearing technology issue? Seems unlikely, gyros can be spun *much* faster.
A puny insect
Gentlemen, I see your one-inch extinct flea and raise you a living Amazon Giant Leech
http://www.pbs.org/wgbh/nova/nature/amazon-leech.html (If you are squeamish, do not follow this link).
Bright flashes ...
"some people even claimed to see bright flashes of light acompanying the boom ffs"
Almost certainly, they did. It's called synaesthesia. It's quite common. For most people it occurs only when one of their senses is overloaded by a sudden and unexpected input. There is some sort of neural spill-over in their mental processes that registers as a different sense. If the triggering experience is sufficiently rare, they may not recognise it as an internal rather than an external phenomenon.
For me, a sudden loud noise also registers as taste (acid on my tongue).
For a smaller number of people, the linkage between their senses is a permanent part of everyday experience. They're not mad, because they are fully aware that it's their own internal "wiring" that is different to that of most other people, and because it doesn't cause them any distress.
True only for the age of the dinosaurs
... and unfortunately not true for the unusual era we are living in, with ice at both poles.
For most of Earth's history, there was no ice at sea level anywhere on the planet, and the climate stability model was very straightforward. It was also very warm - Antarctica had a temperate climate, and the tropics would have been too hot and humid for large mammals like people to survive.
Ice creates instability. Cooler - more ice - more reflected sunlight - cooler, or warmer - less ice - less sunlight reflected - warmer. Positive feedback, not negative. But this too is a gross over-simplification. More heat nearer the equator and more water vapour from the oceans may result in more snowfall over the poles, resulting in more ice even if it's warmer ice. Or not. This all depends on the actual atmospheric circulation patterns. Also ice is a step-discontinuity. Below 0C, you get snowfall, above 0C, you get rainfall, and the transition between water and ice releases a lot of energy.
Ice is just one of the reason why climate modelling for the present is particularly difficult.
Re: any other accelerator built by humanity
We don't know what made it, but Google the Oh-My-God particle (a cosmic ray assumed proton with ~3 x 10^20 eV energy, or about ten million times more than anything men can make!)
The icon suggests what used to happen when Lithium batteries overheated. Are they more stable these days?
Appallingly bad design?
"The service also stores all student essays submitted – with the result that students are often accused of plagiarising themselves."
Surely it should also store who submitted the essay, and spot that it's being resubmitted by the same person?
On the wider issue of citation versus plagiarism, it surely ought to be capable of parsing the common forms of citation, such as text in quotes followed by a citation reference.
It's wrong that the computer is "scoring" students. Surely it should just return the essay marked up to show the areas of concern, which the student can then revise, and finally hand in the (marked-up) essay with a separate explanation for human consideration of anything where he can't satisfy the big dumb computer!
The galaxy's arms are density waves, and all the stars in the galactic disk periodically pass through them. The most everyday example of a density wave is when you are driving along a busy motorway and the traffic abruptly slows to a crawl or stand-still for no apparent reason. Viewed from space at night, it is actually possible to see waves of traffic density moving in the opposite direction to the traffic. Another example is density waves of Guiness moving through the head as it settles.
The word you need
Re: Funny thing
Yes, I know it's a figure of speech, but given the Avogadro constant and the size of Earth's oceans it seems a bit inadequate.
Re: long live the oh my god particle
Well, if the process was 100% efficient, the amount of energy needed is as stated in the article. It's just that we don't have a clue how to concentrate that much energy into a single particle.
Perhaps there are weakly interacting massive particles left over from the big bang, that decompose into high-energy protons with a long halflife, much like radioactive nuclei. There's good evidence for the first part of that statement. Cosmologists call them "dark matter". The other half is speculation.
Re: Penistone ...
Anyone know whether it's true that user-ids at a certain ministry used to be six letters of ones first name concatenated with six letters of one's surname ...
Until Virginia Bottomley landed the top job!
It's not so very different in German
Ficken: to fuck.
Surprised no-one's mentioned the German for "car journey" yet.
Re: "ing"to indicate settlement?
FUCKDORF. Truly brilliant. Thank you!
Re: Penistone ...
My sister knew a girl at school, who dumped a chap called Littlejohn to go out with another chap called Allcock.
Re: There used to be a Lord Fuchs (sp?) in England somewhere.
But isn't that pronounced Fooks? There was also a botanist of that name: witness the Fuchsia. (Try pronouncing that right today and you'll get some funny looks).
A SSD is more likely to survive being dropped - especially being dropped while active! A SSD may be more likely to turn into a brick without warning. Ordinary HDs often degrade slowly, and you can see the developing need to replace them by monitoring the SMART info (especially Reallocations). This is especially true is they are running continuously in a server, rather than being banged around in a laptop. Often it's also possible to recover almost all the data using a tool like ddrescue that retries intelligently.
But never neglect your backups. Some hard drives do turn into bricks without warning. About a third of the failures, if I remember Google's statistics right. My gut feeling is that it's a lower percentage today.
Re: Everyone smells Google money!
I'd call that even more clear-cut, except I probably don't want to listen to it, and I don't have the option to turn it off. Well, not without breaking in.
It's only the RIAA that probably thinks both of us owe them money.
Re: WIlliam Hill
That depends on the nature of the first self-replicating molecular assembly that gets chemistry started towards life. It certainly wasn't DNA or RNA or life as we know it. It almost certainly doesn't exist any more on this planet, because life as we do know it would eat it or disrupt it.
Some speculate it was a clay-like mineral. If so, it might be remarkably tolerant of interstellar radiation and re-entry. Panspermia is a perfectly respectable theory. However, it's all complete speculation. We have no data to prove or disprove it with.
You're generalizing from one datum (and the experiment hasn't been running long enough to give any confidence in predicting the long-term outcome). Maybe intelligence always self-destructs (one solution to the Fermi paradox), and maybe it doesn't. Unknown at present.
If you take a wider definition of intelligence, one can observe that the invertebrates have evolved intelligence up to at least the level of a cat, completely independantly of our branch of the tree of life. (Octopuses, if you were wondering). They've also been observed using tools.
Chirality and symmetry breaking
There's no mystery at the chemical level. L-amino acids form polymers (proteins) with other L-amino acids, and D-amino acids with other D-amino acids. These chains then fold up into spirals and sheets. Spontaneous bonding between L- and D- amino-acids is chemically unfavorable, because the molecules don't fit together properly.
So, if the first self-replicator was L-based, that would have fixed life (or pre-life) on the L-form, and soon the D-acids in the environment were reprocessed by it/them into small non-chiral molecules (i.e. used as food). Once the L-basis of life was established, it could never change. L-based life can't assemble things out of D-bases, but it can and does use them as fuel when they arise spontaneously.
The deep question is why was the first self-replicator to use amino-acid polymers based on the L-form? The answer may be that symmetry was broken at random. The pencil balanced on its point had to fall one way or the other. If so, and if we can ever find any other life to study, there's a 50% chance it'll be based on D-amino acids.
However, there's a much deeper broken symmetry that is itself chiral. The weak nuclear force. Because of this, the binding energy of L-amino acids is very slightly greater than that of D-amino acids. In a mixture formed by inorganic chemistry from achiral precursor molecules, there will be about 100 more L-molecules per mole than D (i.e. 1 part in 6.10^21). Was this enough to tip the balance? Is L-based life universal, thanks to a physical symmetry that broke almost immediately after the big bang itself? Can we ever know?
Back to trivia. In a few cases some living organisms manufacture an L- molecule and others the same molecule in D-form. What's the difference between lemon flavour and lime flavour? One is L-, the other is D-limonene! Why is 7-up "Limon" flavoured? Because in a chemistry lab, it's far easier to cook up a racemic (50/50) mixture, and that's what your fizzy water is flavoured with.
Wagner's ring cycle
I'd suggest that a cimema version of Wagner's Ring Cycle has huge potentential as the worst film ever. It would help if the director han an ego even bigger than Wagner's and fancied himself as a conductor despite being tone deaf. It would help if the leading roles were taken by stars who couldn't sing. And it would help if it were relocated to a completely inappropriate place and time.
Not sure if the cinema version would be longer than the stage version, or edited down to 80 minutes. Perhaps the director made the former, ran out of money, and the studio released it cut down to the latter?
Paris cast as a fat lady who sings?
Unlike DNA and fingerprint scans, a retina scan can't be planted at any crime scene. Unlike DNA, it can't be used to incriminate your children and grandchildren not yet born, or to render you un-insurable because someone works out you have a gene-linked illness, or for certain kinds of blackmail.
OK, a retina scan might be "planted" as a digital copy in a hacked system, but that goes for a photograph or a credit-card transaction as well. Further investigation ought to reveal that a copy was too identical to be a second scan, or was photoshopped.
So why are we more unhappy that the authorities hold our retina scans, than we are that they hold our photographs? What is Paris worried about?
No such problems here. 100% reliability (displacing Netgear, which was going badly downhill). That said, without knowing exactly which model in the ProCurve range, it's comparing oranges with apples. Are you completely sure that the problem is not with your electricity supply? Nothing likes being subjected to high-voltage spikes and surges. I've seen a router with its chips physically exploded after a thunderstorm. A lesser spike may just fry their innards.
Re: Misty water colored mammories
One of our students (probably) was a smart thief. He worked out that there was only one piece of software that used RAM above 1Mb. After that course module had been taught, he stole 3/4 of the RAM out of every machine. Nobody noticed the missing RAM until eleven months later. What chance of getting caught?
I guess he sold his next idea to a Chinese crime syndicate. they bought up tens of millions of low-grade electrolytic capacitors, used forced labourers to replace all the labels with fake high-grade labels, and sold them back to PC manufacturers. All capacitors lasted 2+ years before they started to ooze brown gunk, or (occasionally) exploded.
Re: How did it win? Simple drug-dealer's economics
The first hit is free and you pay for the rest of your life.
Win 3.1 was almost free, as was the version of MS Office that ran on it.
After a majority of businesses had tied themselves into closed file formats ( "addicted") they started raising the price, justifying it with features that most users would have paid to have removed. But, hey, no way out, and no way not to "upgrade" to a more expensive fix.
They were also ruthless with the competition. Drugs dealers kill rivals. So did Microsoft (metaphorically speaking). It blatantly abused its position to put competitors out of business. Sometimes it ended up in court, but win or lose, it knew its competitors were not coming back from the corporate grave.
Re: Trying to hack the experts?
I wonder if we'll get to find out who has the upper hand in this arms race? I'm not convinced that it's possible for even a state to catch a clued-up and paranoid hacker who is merely launching DoS attacks on an internet address from bots. (The real spy-secret kit is doubtless a much harder target, heavily firewalled and hardened or entirely off-net).
Re: Luckily BBS software still exists...
There are a few new things since BBSs first appeared.. There are broadband satellites, for example. Presumably Iranians have friends overseas who can pay for a subscription? So old-style BBSs with small bandwidth requirements could still be connected to the internet in near realtime. Also with a wireless connection to the Iranian net, it would be pretty hard for the authorities to catch someone in the act of operating the router.
The dissenters could even play them at their own game and set up their own open network of ad-hoc peer to peer routers. Sounds like a good use for loads of cheap Rasberry Pi boards. Deploy and forget. Pringles-tube directional antennae to make it hard for the authorities to locate them, if they aren't in the know. With friends in adjacent countries it could even jump the borders. Some time ago I read about battlefield networking using golfball-sized nodes just scattered out of aeroplanes or missiles. A demilitarised version ought to be do-able for £50/node and falling. Maybe something the a news networks should develop, for places like Syria today, and a horribly likely future Iran.
"Interesting times". Is it actually possible to take a whole country off the internet? Ghadaffi tried it in the dying days of his rule, and failed. Now Iran is about to try. I hope they also fail.
Re: Not paying attention
Indeed. It was sheer dumb luck that the Costa Concordia was not a tragedy to match the Titanic. (Luck, or an "outstanding piece of seamanship" on the part of the captain who'd steered his ship onto the rocks in the first place).
What you're after is a brown dwarf - something larger than Jupiter but smaller than a red dwarf star, where nuclear fusion in the core generates just enough heat that the outer layers are the right temperature for liquid hydrogen oxide. Such a place might harbour life long after all normal stars have burned out and the universe has gone dark.
Re: Just a heads-up
You forgot to mention that's only a sixth of the galaxy. The other five-sixths is something wierd that we're calling "dark matter" until we can work out how to get a better look at it.
And there are nearly as many galaxies in the (observable) universe as there are stars in this one.
And that lot, including the dark matter, is only about a quarter of the whole. The other three-quarters is somerthing even wierder than dark matter that we're calling "dark energy".
Now, do we have a volunteer to stick his head into the total perspective vortex?
Re: So any explanation offered...
A star dies by imploding, once it's internal nuclear reactions can no longer make enough heat to fight gravity.
If it started as a completely symmetric sphere it would collapse to a singular point, but stars are not completely symmetric. The evidence (fron observations of Betelgeuse) is that stars about to explode get pretty warty! The implosion will therefore go faster from some directions than others, and the faster-moving bits will slam through the centre and out the other side.
Something like that, anyway. Magnetohydrodynamics with nuclear processes being driven by the moving medium depending on its temperature and pressure would make for a VERY tough modelling problem.
A long time ago I spotted the opportunity to replace four complex multiplications (24 floating ops) by three integer adds, one table lookup, and one complex multiply.
On a VAX CPU of the early 1980s that was a big win.
On today's, it's probably a big lose, because DRAM access is so slow compared to registers. Although, if the entire lookup table would fit into the CPU cache and be accessed many times from cache, maybe not.
And as for implementing it in a GPU ... I don't do this sort of coding any more. One thing for sure, a compiler isn't going to help. You may well have to go all the way back to the maths and choose a different algorithm.
I seem to remember that they have their own CPU design, which looks remarkably like a re-invention (or copy) of the old Digital Alpha architecture. (IMO, FWIW, that was the best CPU ever designed, but in its glory days Digital could bever get near Intel on the fabrication front, and shortly afterwards Digital the company destroyed itself).
In a sense they've also got TSMC (Taiwan semiconductor) which is one of the few outfits that has state-of-the-art fabrication tech.
Wait and watch. The "inscrutable Chinese" stereotype has more than a grain of truth to it.
If I've got my sums right
Energy density of a 100T field in a vacuum = 4 x 10^3 MJ/m^3 (air pretty much the same)
For comparison, energy density of gasoline = 34 x 10^3 MJ/m^3, less than 9x higher
Energy density of a magnet field goes as the field strength squared. This may give some insight into the self-destructive tendency!
Re: You don't need new laws
Here in the UK, yes, and even more so in the EU. It's a USA story.
Tales of the unexpected
Anyone else remembering the one where the company isn't happy just to interview the husband for a top-level promotion, but insists on interviewing his wife as well in a social setting?
She comprehensively blows his chances.
Which is exactly what they want, because he's using his job to steal from the company!
Re: I would have thought the simple answer is...
Possible, even probable, grounds for dismissal if they later find out that you lied to them.
I *really* don't have a Facebook account.
I still don't get it.
I still don't get it. Why do people feel a need to store every embarassing detail of their private lives in a huge database owned by a for-profit corporation, and then expect to keep it private?
As an old proverb says,
"Don't make love by the garden gate / Love is blind, but the neighbours ain't!"
I've always wondered why they didn't make Opterons with many Hyperchannel links many years ago, so that system-builders could take Hyperchannels through a little buffer chip between boards, or fruther using optical technology. Why did they stop at three, while they watched people building clusters using slower and less integrated technologies?
Only obvious with hindsight?
Indeed. I wonder if he knows what an F1 hybrid is?
It's my favorite way of upsetting educated racists. To get (say) plants with big red flowers, you selectively breed for such, in several completely separate groups. The trouble is in-breeding. The flowers get bigger and redder, but other recessives make the plants become weak and disease-prone. Then you mix up the groups. The bad recessives are different, and recede. What they all have in common is big and red, and they grow strong and healthy and much bigger and redder than any of their parents.
How does that annoy racists? It's setting the trap. You now get them to agree that in the past, humanity lived in small villages and rarely married outside even a 10-mile radius. (The inbred village idiot was commonplace).
Then you get them to agree that humans with free will direct their own breeding through their choice of partner. What are they choosing for? Strength, beauty. Intelligence? Probably all of those. Universal choices? Also probable. Weak Stupid offspring don't have great chances in the world. (I'll pass on ugly: beauty is in the eye of the beholder).
And once you get them to agree that every village was selecting these traits, offset by inevitable inbreeding, you point out that the industrial revolution increased 10 miles to 100, and that air travel has increased it to span the globe. Interracial marriages are creating human F1 hybrid children. Strong, beautiful, intelligent people.
I can't prove it, but it's far more plausible than the opposite. And racists? the inbred village idiots are still with us. They seek each other out!
Re: Wait, what?
Not how I read it in that context. 4 letters starting with C. No, not the usual C-word. Definitely racist.
Murderers often get 15 years, rapists can get less than five. Is murder only 100 times worse? Is rape only 30x worse?
It's not to say he's anything less than a horrible person, but as the proverb says "sticks and stones may break my bones, but words can never harm me". If we can't bring back a day in the stocks (limited to squishy projectiles), community service would have sufficed.
Re: they can try
Blocked by a granite wall - are you sure? I've sent ordinary Wireless-G Ethernet 30 metres sideways and down through a reinforced concrete floor. Didn't even need directional antennae. Only got 5Mbps out of it, but it worked. How many Mbps does one need to read a meter?
Re: Rise Of The Socialists
Actually, no. If the abuse of power got that bad, then everyone would do what the criminal classes do already: an insulation-displacement bypass between the streetside of the meter and the house.
It's called theft at present, not protest.
Re: Why be part of a bad health experiment in your own home?
"Do some people become ill around certain common electrical devices? Also undoubtedly true."
Cite proof, please. A double-blind test.
Put a person who claims to be electro-sensitive in a screened room (Faraday cage) with a concealed wireless router, cellphone, whatever. Neither the experimental subject nor the person telling them what to do is allowed to know beforehand whether it is turned on or not. Ask them how they feel BEFORE finding that out. Repeat until a statistically significant body of evidence is gathered.
In a less kind and possibly unethical variant on this experiment, let the subjects know where the router is concealed (say, above a ceiling tile) but don't tell them about the spycam recording their every move and the *other* concealed router permanently turned on. I'd bet 9/10 "electrosensitive" subjects would feel the need to sneak a look at the router (and then report back that they're fine when they see it's turned off, despite the fact that the other one should be making them feel ill.
Might the point be that some people actually like to listen to their music in high fidelity? Which is quite definitely not what you get with a lossy-compressed download.