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* Posts by Nigel 11

2491 posts • joined 10 Jun 2009

SCO keeps dying, and dying, and dying

Nigel 11
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Re: They were being propped up...

Wasn't M$ quite openly putting money into SCO?

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Nigel 11
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Re: I've seen this film...

The film I'm thinking of is "Carrie". Sorry if that thought gives you nightmares too.

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Jimbo Wales: Wikipedia servers in UK? No way, not with YOUR libel law

Nigel 11
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Re: Truth hurts

In practical terms, if they have no assets in the UK there's nothing to be gained by suing them here. Or at least, there won't be if the jurisdiction(s) that they do hold assets under are not willing to kow-tow to UK libel law by enforcing the judgement of a UK court.

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HP must throw its PC biz overboard to survive, says analyst

Nigel 11
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Please, separate printers and PCs!

HP's printer business ought to be able to survive a spin-off. It might even thrive by returning to the original HP company ethos. There's no synergy I can see between the design and manufacture of printers and that of PCs. Indeed there may be negative synergy. A competing manufacturer of PCs is hardly likely to bundle an HP printer (ie directly support a competitor) when it can bundle one from Lexmark, Kyocera, or several others who aren't competing to sell PCs.

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NASA's $2.5bn Curiosity rover: An Apple PowerBook on wheels

Nigel 11
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Re: Nope

I wonder if they might have been able to build it with a non-hardened "co-processor" in a powered-down state until it arrived? (If I understand right, radiation is far more damaging to electronics that's powered-up than if it isn't ... though I'm not sure whether Mars's atmosphere is an adequate radiation-blocking substitute for Earth's in this context).

Downside: weight penalty. Upside: a *much* more powerful computer available, should it survive transit.

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Euro NCAP to mandate auto-braking in new-car test

Nigel 11
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Re: @iCode

With filament brake lamps it's easy to prove that they weren't working (given forensic investigation). If they were on when they got broken (or activated afterwards) the tungsten filament will have burned into tungsten oxides. If they were disconnected that can't happen. Likewise if the filament was broken prior to the impact.

With LED arrays it may be harder.

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How one bad algorithm cost traders $440m

Nigel 11
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Unhappy

Re: Wow!

Reminds me of a plain ordinary modem, where the connection to the telephone socket wasn't sufficiently secure. One day we got a four-digit phone bill. It turmed out a cleaner had been unplugging the modem, plugging in a telephone, and having long conversations with somebody in the West Indies.

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Nigel 11
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FAIL

Re: Gamblers deserve to lose

Wrong.

Gambling is investing when the expectation value for the profit is negative. Bet in a casino, and averaged over enough bets, you are losing 1/37 of your capital for each bet (in a UK casino with one zero on the wheel).

Investing is when the expectation value for the profit is positive. You might imagine an eccentric millionaire who returned double your stake on all zeros, so you could predict that you'd be up by 1/37 for every spin of the wheel. Buy shares in a big blue-chip company, and that return is called a dividend.

Of course, investing in companies is to some extent a matter of judgement rather than probabilistic certainty. You have to be right often enough if you're going to make a profit. A few people can even judge horses right, and for them a betting slip is an investment not a gamble. They're rare. Successful stock-market investmenting is easier, because an honestly run company is trying to make money for its shareholders, not lose them money.. (You might guess that I do not invest in banks. I've long believed banks run on the principle of "heads I win, tails you lose". )

There's also a social benefit to investing even when it makes a loss. You're lending your money to a company that hopefully is in a business that you believe ought to be carried on. It's often said this applies only to those who buy new equity issues. Wrong. The initial investors probably wouldn't invest, if there was no way ever to sell up. A company is supposed to last longer than the few decades between having earned surplus capital, and wanting to spend it on one's retirement. The stockmarket is a mechanism that makes people more willing to invest their capital in the first place.

It becomes less clear when instead of doing one's own investing, one delegates it to a pension fund manager or suchlike. That's because your delegate would like to put as much of your money into his pockets as he can get away with. That, however, has nothing to do with whether it's investing or gambling.

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Nigel 11
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Re: Nah... It's the other way round.

The obvious safety is to have a trading limit, if only for debugging! After it's done $(LIMIT) of trades, it stops, until a human has checked the goings-on. Once they're happy it's working they might set the limit to effective infinity.

The other obvious limit is $(MAX_LOSS), but the danger there is that it might think it was making a profit when it wasn't (which appears to be pretty much what happened).

Personally I think program trading is one of the casino-finance things which ought to be banned, or at least heavily restricted. Otherwise, sooner or later there's going to be another bug like this one with added naughts. In other words it won't just bankrupt a bunch of speculators, but it'll also do major damage to the real economy.

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Hundreds of websites go titsup in Prime Hosting disk meltdown

Nigel 11
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Re: More fun if the card goes

Drives from one controller will often not talk to later versions of the same controller (or have I just been unlucky)

No, thats one of the several reasons that these days I refuse to countenance hardware RAID controllers.

Another is the case where the manufacturer of your RAID controller goes out of business and the only place you can get a (maybe!) compatible replacement is E-bay. And then there's the time you find out the hard way that if you swap two drives by mistake, it immediately scrambles all your data beyond retrieval. And if there's a hardware RAID card that uses ECC RAM, I've yet to see it.

Use Linux software RAID. Modern CPUs can crunch XORs on one out of four or more cores much faster than SATA drives can deliver data. And auto-assembly from shuffled drives does work! You do of course have a UPS, and you have of course tested that UPS-initiated low-battery shutdown does actually work before putting it in production.

(Enterprise RAID systems with sixteen-up drives may be less bad, and in any case it's a bit hard to interface more than 12 drives to a regular server PC. It's little 4-8 drive hardware RAID controllers that I won't touch with a bargepole.

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Nigel 11
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Re: This is CRAP!

You really need to data-scrub, and watch the SMART statistics for the drives themselves, and act pro-actively. If the number of reallocated blocks starts increasing, replace that drive BEFORE the array is in peril. Sometimes drives do turn into bricks just like that, but in my experience and that of Google, an increasing rate of bad block reallocations after the array is first built is a warning not to be ignored.

If I were ever running a big-data centre, I'd insist on buying a few disk drives monthly, and from different manufacturers, so I could assemble new RAID arrays from disks no two of which were likely to be from the same manufacturing batch. A RAID-6 made out of drives with consecutive serial numbers is horribly vulnerable to all the drives containing the same faulty component that will fail within a month. I'd also want to burn in a new array for a month or longer before putting it into service. If a new drive is going to turn into a brick, it most commonly does so in its first few weeks (aka the bathtub curve).

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Amount of CO2 being sucked away by Earth 'has doubled in 50 years'

Nigel 11
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Boffin

Where is it all going?

In the first instance, into plants. Measuring CO2 in the atmosphere shows minima every Northern hemisphere summer, and maxima every winter, as the leaves in the Northern hemisphere's deciduous and annual plants grow and decay. (The land area of the Southern hemisphere is considerably smaller so it doesn't fully compensate).

Some of that plant matter doesn't decay annually. It may be trapped for longer, as dead roots, humus in soil, peat bogs, and organics in sediment.

What's going on with plankton in the oceans is probably the most important thing long-term. Much of the carbon in dead plankton sinks down to the ocean deeps, from where it may not be released for geological ages. Is more CO2 being matched by an increase in plankton and therefore accumulation of organic matter on the deep ocean floor? We don't know. I'd neither count on it, nor rule it out.

Incidentally, our agricultural practices that create unnatural dust in the atmosphere are almost certainly resulting in an increased supply of iron to the ocean surface. And the biggest limitation on oceanic plankton growth is a shortage of iron. Accidental geo-engineering in progress?

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Nigel 11
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Boffin

Root to shoot ratio

How much of this is explained by plants optimizing themselves?

As "food", plants need CO2 from the atmosphere, and everything else from in the ground. They'll grow so as to balance the availability of those two sources. More CO2 in the atmosphere means that the plant can grow faster and bigger, but only if it shifts its growth to favour its root system, thereby obtaining a proportionately increased supply of water and minerals.

When the plant dies, the deeper its roots, the longer the carbon in them stays out of the atmosphere.

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Hobbyist builds working assault rifle using 3D printer

Nigel 11
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Re: This one is way too easy

Could you make a gun barrel out of plastic, even for just one shot at short range? I'd have thought it had to be steel to resist the firing pressure (and of course extreme precision machining needed as well for long-range accuracy). Definitely the hardest component to DIY and the one most in need of regulatory control.

If I wanted to kill someone at short range I'd make a crossbow. Just as deadly, less noisy, no technology needed that they didn't have in the middle ages (though modern alloys and composites would let you make it smaller and more powerful).

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Nigel 11
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Re: This is going to get interesting soon...

Polythene and paraffin wax are pretty similar. (Same chemical formula CH3.(CH2)N.CH3, much bigger N for polythene). I expect with a bit of tinkering, they're interchangeable. At the printer end, the problem would be feeding wax "wire" which wouldn't have the tensile strength of polythene. At the lost wax end, you'd need to investigate whether it burns out of a clay mould as cleanly as wax. Molten wax will rapidly soak into porous clay. With polythene, you'd probably have to "cook" it for longer, and watch out for problems caused by gas pressure build-up behind a still-solid or highly viscous polythene plug.

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Nigel 11
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Re: Metalwork class

Lathes and milling machines are computer-controlled these days. Have been for quite a while (since before 3D printers arrived).

I expect that a keen hobbyist could pick up an old manual milling machine and convert it to computer operation in his garage. You'd just have to replace the wheels that are turned by hand with appropriate stepper motors and sensors and controllers. The rest is programming.

BTW learning to use a manual lathe or milling machine is not at all hard. (Learning to use it well, that's quite another matter).

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Nigel 11
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FAIL

Re: Bloody wonderful, dont idiots ever think first?

It's just as likely that microdots or similar will be added to the plastic, so that an item can be traced through the purchasing system to the person who bought it.

Fail. Make your own feedstock out of commodity plastic items purchased at Wal-Mart, if you've got something to hide. Can it be that hard to work out how to re-melt and extrude polythene, ABS, etc.?

Restrict the technology and it will be driven underground, which means that you won;t be able to use it for tinkering with harmless things, but there will still be someone turning out knock-off copies of gun components for a black-market profit. Same as for recreational drugs, commercial sex, illegal porn, ....

At present the best hope is to restrict the gun barrels, which are clearly the hardest components to make. And despite the above, I'm still glad I live in a country where posession of a complete gun is strictly controlled. I feel I have less to fear from gun-bearing career criminals than from gun-bearing lunatics or gun-bearing mobs.

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Nigel 11
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Re: Bloody wonderful, dont idiots ever think first?

Surely would make a lot more sense to regulate guns. Or if you insist on the right to bear arms, to insist on the gun barrels being "serialized" and controlled rather than the bit which works even if printed out of plastic.

Out of interest, how much does a computer-controlled milling machine cost these days? How hard would it be for a hobbyist to make his own computer-controlled milling machine out of a surplus manually-controlled milling machine plus some stepper motors and controllers?

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Nigel 11
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FAIL

Barrel

I wonder whether J. Random Lunatic really cares much about "precise". How precise do you need on full auto at a range of ten yards?

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Neal Stephenson on swordplay, space and depressing SF

Nigel 11
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Boffin

Immortality - cause for optimism?

Just realized, no-one seems to have mentioned the one SF dream that might make things a lot better in a hurry and which might come about in some of our lifetimes. Immortality (second-grade). It may be possible to slow down or turn off the senescence mechanism that's biologically programmed into our stem cells. If perfect, we'd then enjoy the same life-expectancy and health at 70, or 100, or 200, that we enjoyed at 30. If less perfect, we might still get a few more decades of middle-aged health. We'd still die, eventually, of accident or incurable illness or other sorts of ageing that medicine couldn't deal with. But we might start treating the future of our planet with the respect it deserves, if we knew we might be living a few hundred years longer, rather than just a few decades.

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Nigel 11
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Boffin

Re: Sci-fi 'tech'

Actually there is at least one technological revolution in full flood right now: biotech (and GM). It's (surprisingly? ) far under most people's radar, because the main applications so far are

- pharmaceuticals, which we don't think about until we're ill, and then either the medics can cure us, or they can't and we accept our fate. No change since the middle ages, really, except the pills work somewhat more often these days.

- food, which we eat the same way whether it's GM or not, and most of us don't really know or care.

- raw materials (made by bacteria, GM or just selectively bred) which then go into the same old manufacturing chains. Once upon a time, citric acid was extracted from citrus fruit.

But one day soon, that might change dramatically. For example, on the optimistic side, what if instead of having a house built, you could just plant some seeds, and occasionally spray the developing house-treees with hormones to control the shapes of the walls and windows? Or grow GM seaweed that concentrates your element of need (Gold? Uranium? Europium?) out of the seawater, courtesy of a precisely engineered molecular sieve? Or solve global warming with a crop plant engineered to grow its roots far deeper than nature says it needs to, thereby burying lots of carbon for a long time?

And on the pessimistic side, it could all go horribly wrong (the cliche being zombie-horror fiction).

Some SF authors do get it, but a lot of those I've read illustrate that people who know their bioscience often don't know their physics.

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Nigel 11
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Alert

Mirror of our times?

The state of SF is because it's reflecting the times we live in, or extrapolating them into the future. And there's not much to be optimistic about in today's society.

IT, for example, seems to have gone from being an enabling tool, to being a tool for repression. Omnipresent surveillance. No respect for privacy. Patent wars (that the small guys can't afford to fight). A complete disrespect for sound engineering principles, especially if they get in the way of making money in the short term. And worst, we've layered all the new infrastructure (which is frighteningly fragile) on top of old infrastructure (which was once robust, but which we're allowing to crumble, because our leaders don't understand that it supports the new stuff).

More widely there are issues of resource depletion, population increase and ecological overload, that are almost universally regarded as "too hard" and ignored. By the time they bite so hard they cannot be ignored, it'll be far too late to fix them.

Personally, I'd call today's reality a dystopia, and I can't see it getting any better. Pessimism is assuming it's going to get much worse very fast in the near future. A global crash (and not just the financial one, that we're already in). Thinking things are going to get a lot better very quickly isn't optimism, it's denial. Optimism is thinking that we'll muddle though, somehow.

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Hidden Grand Canyon-sized ICE-HOLE hastens Antarctic melt

Nigel 11
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Cat's cradle

Yes, I read it. The physics was nonsense. As a parable, I've read much better SF. I found the fall of Namqem particularly worrisome (along with most of the other back-story in Vinge's "A Deepness in the Sky").

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Nigel 11
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Boffin

Re: Geo-engineering

No reason for a gel to resist ice shear (which wouuld be quite impossible). As I understood it, liquid water circulation under the glacier is bringing in warm seawater which is melting the ice from below. Gel that water and the circulation would stop, which would slow down the melting. It might even result in the gelled water becoming cold enough to freeze.

As for the dangers of meddling with things that aren't well-understood and which consist of lots of interlocked feedback loops, I agree. Except, we've already done that on a massive scale with atmospheric CO2. If sea level is rising seriously fast because of the melting of this area of ice, slowing or stopping the melt might be the least bad option. Especially so, if there's evidence that it was frozen all the way down in recent geological time.

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Nigel 11
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Boffin

Geo-engineering

There's a way to slow this process, if anyone dare try. Inject a gelling agent into the water at the bottom of these valleys, so it can't circulate to the ocean. It's amazing how small a quantity of the right material can turn water from a runny liquid into a viscous or near-solid gel. Once immobilized, it might even freeze solid.

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OCZ Vertex 4 256GB SSD review

Nigel 11
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DAK ...

Of interest only to a techie, but does anyone know why they've rotated the controller chip 45 degrees with respect to the others? It's not obviously making the most efficient use of PCB real estate (and neither does it look "cool", not that many people look inside the plastic case).

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Facebook's Zuckerberg awarded privacy patent

Nigel 11
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FAIL

Re: Gobsmacked

So how on earth did we manage to have both friends and privacy in the days before the internet existed?

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Google Nexus 7 blighted by brightness blunder

Nigel 11
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Re: Mines fantastic

Or that he's reviewing one with a faulty display, and he ought to return it for a warranty replacement.

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Santander's banking website craps out

Nigel 11
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WTF?

24/7

That's an expensive and silly promise for a bank to make (if they actually made it, which I doubt).

24/7 is much harder than (say) 5am to 1am six days/week, and I for one don't care if my bank is occasionally offline for planned maintenance between (say) 1am and 5am. I know that at least one of my financial services providers starts its scheduled downtimes at midnight - a bit early for my liking (which is how I know) but not enough to actually annoy me. Likewise, if they sometimes need to take a longer time-out on a Sunday, I'd not be very bothered. Certainly given a choice between 24/7 or free banking, I'd take the latter without hesitation!

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Nigel 11
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U-CLOD does not begin with C

I think I spy someone who didn't get the joke?

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The Higgs boson search continues ... into ANOTHER dimension

Nigel 11
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Boffin

Re: If you knew SUSY like I know SUSY...

Non-scientists often ask for a simplified, non-mathematical explanation. What they don't understand is that the two adjectives are mutually contradictory. Mathematics is the simplest language we've got for describing how the universe works.

And no, we don't know why. Maybe God is a mathematician.

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Nigel 11
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Re: Is there an end point?

It's also possible to have no end-point or start-point, if time, space and any other dimensions that may exist are all cyclic.

This is not a popular viewpoint, given the overwhelming evidence that about 20 Gyears ago, the entire universe was compressed into a very matter-dense, very hot, very small and very ordered volume. We call that the big bang. Nevertheless, it's huge leap from that, to assuming that it all originated in a mathematical singularity some tiny fraction of a second earlier. That's a leap from the unknown to the fundamentally un-knowable. From something that might one day be understood by observation and deduction, to something that absolutely cannot be.

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Nigel 11
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No

More like the non-luminiferous aether. Photons do not interact with the Higgs field, therefore remain massless, and consequentially can exist only by travelling at the speed of light. Photons (and maybe gravitons, if they exist) are the only things which do NOT disturb the Higgs field.

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Nigel 11
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Re: Anisotropy

Not yet at enough sigmas to even justify calling it a hint. Well, that if the lines in the New Scientist graphic were the conventional length of one sigma. Hopefully they'll have a better idea before the CERN upgrade commences.

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Nigel 11
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Boffin

Re: "what happened before the big bang"

Actually (in theory) black holes evaporate, albeit very slowly for large ones. (In practice, we don't have any black holes that we can observe in enough detail to know). Anyway, as they evaporate they spit out photons, and so the end-point of the universe is a sea of stable particles, mostly photons, spread very thin by the expansion of space-time.

The other thing that seems to be happening is that the expansion of space-time is accelerating ("dark energy"). This is observational astronomy, not theory. This might mean that the ultimate end comes much sooner (relatively speaking - mere gigayears or terayears - tomorrow is unlikely but not impossible) when the velocity of every particle in the universe with repect to every other particle becomes greater than the speed of light. All interaction ceases, there are no events left to happen, the universe is done. Everything is past. Time, and "what happens next?", no longer have meaning.

(There's no ban in relativity on purely geometric speeds in excess of the speed of light - the framework can expand faster than the speed of light. That's why we talk of the known universe, because there may be parts of the whole universe that are receding from us at greater than the speed of light, which we'll never be able to see unless the expansion slows down or reverses).

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Windows 8 'bad' for desktop users - Gartner's one-word review

Nigel 11
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Facepalm

Re: Well Duh!

> THAT is why Microsoft is moving away from the mouse, which was always a terrible input device.

Just in case you are not trolling, and haven't worked this out, despite your claimed pain.

A mouse is the only pointer device(*) that is not anchored to the rest of the hardware, and is therefore capable of being used in a way that does NOT cause muscular strain or carpal tunnel syndrome. The problem is that 9/10 users don't know how, and 9/10 won't change even when you show them how.

Take the mouse off the desktop and put it on your thigh. Learn to move the cursor with several swipes, rather than thinking you have to move it from top left to bottom right without taking it off the surface it's resting on.

This way, you can control your computer without using any muscles other than those in your fingers, until you have to switch to the keyboard. It might feel awkward at first (I can't remember). So does riding a bicycle.

(*) actually not quite true, the other option is a trackball.

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Nigel 11
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Linux

Elephant in the room?

A long time ago, Microsoft ripped off an elephant -- called IBM. Supposedly, elephants never forget.

It it possible that IBM will decide the time is ripe for revenge? In the form of an IBM-supported Linux-based corporate desktop offering? They've certainly got the know-how and experience.

Personally, I'm thinking "if only". They'll never have a better chance.

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Nigel 11
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Mushroom

> But only a moron will still be struggling after a day or two

Let's assume you're right, and say one day. That means the added cost of adopting windows is one day's salary. Multiply up. Or just think of the economic loss as being the same as a flu epidemic (regular flu, not the killer variety).

That's the downside. Now, what is the upside, that makes you happy to pay for this shoer-term loss of productivity? Upside for your organisation, that is. Not for Microsoft.

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Skype: Nearly half of adults don't install software updates

Nigel 11
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Re: Fecking Mozilla

Mozilla are one of the few that recognise the problem. What you want is the Extended Support Release of Firefox. Bugfixes only, not new features you never asked for.

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BIG BOOBS banished from Linux kernel

Nigel 11
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Headmaster

Re: Who the hell cares?

One should also note that in UK vernacular (not sure about USA, Oz, etc) a boob can mean a mistake. Referencing uninitialized storage can accurately be described as a "big boob" for a programmer.

BTW, 0xB16B00B5 has been patched to 0x0DEFACED

Personally I wonder why the original wasn't 0x0B00B1E5

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Nigel 11
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Boffin

Re: Are you kidding me?

The number is written into "uninitialized" storage in a VM environment where uninitialized is not an option. It's useful to a programmer to have a distinctive hex pattern. If he sees that in a register after a core dump, it's a pretty good clue as to what went wrong.

These days in scientific codes, you want to have everything initialized to an IEEE Floating-point NAN pattern ("Not A Number"). Then, instead of crunching garbage up with your data if a bug references uninitialized storage, your program immediately throws a floating-point exception. ISTR NAN can also be customised to have humorous hex representations (or more boringly, to encode the address of where it came from).

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Nigel 11
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Black Helicopters

Re: Oh noes 0xDEADBEEF

I believe that was also a patch to the original version which was 0xDEADBABE. That code was written at about the same time as a young lady died in a car belonging to one of the Kennedy dynasty (ie rather before my time).

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Ocean-seeding experiment re-ignites geo-engineering debate

Nigel 11
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Boffin

Re: how much carbon is burned

Very little. The reason is that the soluble iron is like a catalyst for the plankton. It's a shortage of small amounts of iron which limits the rate at which plankton can grow. Supply those small amounts, and a massively greater weight of plankton grows, much of which is carbon. And when it dies, it sinks, taking the carbon to the ocean deeps. (Also the iron, which is WHY it's in short supply in ocean waters).

I wonder if there's a stabilizing feedback mechanism here. We're causing the oceans to become more acidic as they absorb the CO2 we emit. Will the increased acidity increase the amount od iron that the oceans can dissolve out of the dust that the winds blow from land deserts out to sea? If so, that means more plankton dragging more CO2 down to the ocean deeps.

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Judge: Apple must run ads saying Samsung DIDN'T copy the iPad

Nigel 11
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Meh

Re: Timing is perfect!

The judge can't order Apple to change its corporate mind. The case-law implications in other jurisdictions would be the same, whether or not the judge had ordered the publicity. With respect to future Apple vs Samsung action, the publicity order is a non-issue.

Whether it'll hurt Apple's sales remain to be seen. People do not like bully-boy companies, though to what extent this will tar Apple with that brush remains to be seen. Their Teflon coat is probably good for a while yet.

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Backups? Use disk. Archives? Disk. Particle accelerators? Fine, tape

Nigel 11
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Re: Spun down or Offline disk?

> Because when a disk is spun up, you notice if it's failed. When a disk is on a shelf, there is no notice, unless you spin them up every so often to check them, in which case you rapidly start to lessen and possible advantage.

I'm not convinced. Many office PCs are powered up and down daily. Many are configured to save electricity by sleeping with the disk spun down, several times per day. They're acceptably reliable. I look after ~100 such and see 2-3 HD failures per annum. With about half there's advance warning of incipient failure (SMART error counts) .

For an archive, the disks would be in RAID sets (multiple partity disks, at least two). Have the automation spin the disk up once a week if that hasn't happened by normal operations. Fail? same as any other failure in a RAID system. (Automatically) replace the failed disk, reconstruct, set bright red failed light on failed disk canister so dumb tired human knows which drive he's supposed to unplug and toss. Disk life expectancy would be close to shelf life, if they were powered up only for a couple of hours, one day in seven. MTBF ten years? Close to office PC disk life, if active two hours every day and spun up and down a few times per day. Certainly no worse than three years.

Main problem I see with a big disk archive is the running cost of replacing failed disk drives. There again, how long are tapes safe before you are advised to copy them to new media? Cost per Gbyte is pretty much the same. In a few years time, will tape have caught up with 10Tb disks? And if BPM/ HAMR tech gets out of the labs, we'll probably have 100Tb disks by 2022.

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Nigel 11
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Re: Spun down or Offline disk?

> I would not trust a disk to be off for a year or more and expect it to come back

Why distrust that, any more than you distrust a disk that's powered up, wearing out some mechanical or electronic component with an in-service life considerably less than its shelf life?

Anyway, for archive you are surely using RAID techniques with multiply redundant disks, so a single failure or even a double failure won't hurt.

"New" disks may have been in the pipeline from manufacturer's testing to your installation for many months. True, new drives fail rather more often in their first few weeks and occasionally are even DOA. Most, though, are just fine. So as long as you have RAID with two or more redundant disks you should be OK.

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Nigel 11
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Happy

Re: I remember a time...

Yes, it's very important to match the reliability of the storage to the importance of being able to retrieve it down the line. My CD archive is of physics data most of which will never be read again, and of which a statistical sampling (say 80% of the files) will be almost as good as 100%.

Wonder if anyone would be interested in software to create RAID-6 sets of DVDs? (Not that I have time to write it, but someone might like to run with the idea, especially if their data archiving needs are a few tens of Gb per run).

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Nigel 11
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Boffin

Spun down or Offline disk?

No reason to keep your archive disks powered and spinning. If access is infrequent, the system should spin them down between accesses. If even less frequent, they could be unplugged completely (robotic hot-swap SATA storage? Or just some custom electronics to cut the power completely on drives that won't be accessed again for weeks.

Arguments have raged for decades on whether drives last longer spinning or powered down. I don't expect a resolution any time soon. Whenever someone has a statistically valid answer, the drives for which it's an answer are many years obsolete.

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Nigel 11
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Re: I remember a time...

Anyone know why they can't / don't do write-once optical tape? Holes burned in a stable dye layer between polymer films? 2400 feet of 1-inch tape is the area of about 1500 DVD-Rs, or about 7Tb at the same data density.

BTW I have no trouble reading CD-R's burned over a decade ago, that have been kept in sleeves in the dark at office temperature. Ditto DVD-R going back slightly less time. People who say they don't last, are probably letting sunlight get to them.

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Nigel 11
Silver badge

Re: Tape this !

> Cheaper TB for TB? Really?

DLT-S4 cartridge, 800Gb (1.6Tb compressed), £40

2Tb disk drive, £80 at inflated post-Thai-flood price. £50 expected again soon-ish. 4Tb drives on the market but so far at "premium" prices.

I make that a tie, depending on whether your data is already compressed or hugely inefficient. Now, if the argument was whether you'd be able to read it after twenty years' offline storage, tape might make the better case. Certainly, the results of the accelerated ageing tests for tape don't need to be taken with quite as much salt. But if the data really matters, you'll probably be reading or even re-copying every couple of years to be on the safe side of entropy.

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