Hard Drives 101: Magnetic Storage

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Even though we shun hard drives in this era of SSDs, magnetic storage is really quite remarkable. In this piece, we dive into the history of hard drives, dissect the technology that makes them work, and explore the advances that give us 3 TB drives today.

Hard Drives 101: Magnetic Storage : Read more
 

soccerdocks

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"Density initially grew at a rate of about 25% per year (doubling every four years)"

If density grows at 25% per year it would actually double in just barely over 3 years. At 4 years it would be 144% greater.
 

johnners2981

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[citation][nom]soccerdocks[/nom]"Density initially grew at a rate of about 25% per year (doubling every four years)"If density grows at 25% per year it would actually double in just barely over 3 years. At 4 years it would be 144% greater.[/citation]

No you're wrong, how embarrassing :). You're using compound interest. Quit trying to be a smartass
 

Device Unknown

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[citation][nom]johnners2981[/nom]No you're wrong, how embarrassing . You're using compound interest. Quit trying to be a smartass[/citation]

I'm no math guy, in fact i suck at it, but I see his point, why wouldn't it be compound? and even at compound interest is 144 still accurate? please enplane
 

soo-nah-mee

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I believe soccerdocks is right - example...
Beginning value: 10
After one year: 12.5
After two years: 15.625
After three years: 19.531 (Almost double)
After four years: 24.41
 

johnners2981

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[citation][nom]Device Unknown[/nom]I'm no math guy, in fact i suck at it, but I see his point, why wouldn't it be compound? and even at compound interest is 144 still accurate? please enplane[/citation]

Please enplane??? Compound interest is used to calculate interest and not things like density.
They were right in saying "doubling every four years" and he was trying to correct them when there was no need so showed him who's boss, oh yeah
 

johnners2981

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[citation][nom]soo-nah-mee[/nom]I believe soccerdocks is right - example...Beginning value: 10After one year: 12.5After two years: 15.625After three years: 19.531 (Almost double)After four years: 24.41[/citation]

His calculation is right not the application, why is he using compound interest to calculate the percentage increase in density? It doesn't make sense.
 

soo-nah-mee

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[citation][nom]johnners2981[/nom]His calculation is right not the application, why is he using compound interest to calculate the percentage increase in density? It doesn't make sense.[/citation]It's not compound "interest", but it is compounding. If you say something increases 25% each year, you can't just keep adding 25% of the original value! Silly.
 

striker410

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[citation][nom]soo-nah-mee[/nom]It's not compound "interest", but it is compounding. If you say something increases 25% each year, you can't just keep adding 25% of the original value! Silly.[/citation]
I agree with the others on this one. Since it's adding 25% each year, it is compound. You are thinking of it from the wrong angle.
 

asymetriccircle

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ok i dont know all this interest shenanigans, but that first diagram, shouldn't the magnetic field be going the other way given the direction of current they show? i was just thinking right hand rule.
 

johnners2981

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[citation][nom]soo-nah-mee[/nom]It's not compound "interest", but it is compounding. If you say something increases 25% each year, you can't just keep adding 25% of the original value! Silly.[/citation]

How's it silly? If you're going compound annually then why not compound it monthly, daily, hourly then???
 

soo-nah-mee

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[citation][nom]johnners2981[/nom]How's it silly? If you're going compound annually then why not compound it monthly, daily, hourly then???[/citation]You HAVE to compound it at some interval, and since the author said 25% PER YEAR...
 

johnners2981

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[citation][nom]soo-nah-mee[/nom]You HAVE to compound it at some interval, and since the author said 25% PER YEAR...[/citation]

You don't have to compound it, the author also says it doubles in 4 years which obviously involves NO COMPOUNDING
 

bobfrys

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Either way the author made a mistake. If you say density increases 25% a year that means 25% larger THAN THE PREVIOUS YEAR.

If they extrapolated that 25% number from doubling every 4 years then they did their math wrong. It all depends which number is the real number, and which number did they incorrectly pulled out of their ass.
 

jamie_1318

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You have to compound it with the same length as the growth rate is factored in. That's the only way the metrics make sense. It means that each year is 25% more storage than the last year.
 

PhoneyVirus

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Getting this for Christmas from the girlfriend I have 18th edition witch was the best version for the FSB X48 last of its kind the good old days, the 19th Edition felt like there was to much information took out. I'm hoping 20th Packs the info about Core 5/7 and some AMD, I found older versions didn't talk about ADM much so again I hope its packed. Looking forward to reading the book this winter well after Christmas then Windows 7 inside out deluxe edition here I come.
 

Nnymrod

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Hard drives are really cool, and while SSDs are definitely better in almost every way, and are most definitely the future... I still like hearing platters spin up :) And they will be the best option for backup drives for awhile.
 

Haserath

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[citation][nom]asymetriccircle[/nom]ok i dont know all this interest shenanigans, but that first diagram, shouldn't the magnetic field be going the other way given the direction of current they show? i was just thinking right hand rule.[/citation]
Actually he is showing the electron flow with the arrows in the first diagram, but the current is the 'positive flow' which is the opposite of the electron flow.
 

Haserath

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[citation][nom]Nnymrod[/nom]Hard drives are really cool, and while SSDs are definitely better in almost every way, and are most definitely the future... I still like hearing platters spin up And they will be the best option for backup drives for awhile.[/citation]
Except as of right now, solid state storage has a capacity limit that won't go much further(as a guess). The oxide layer in solid state drives right now barely holds up to a few thousand writes, and as each 'holding cell' for the bits gets smaller this oxide layer becomes less durable. It won't be long before we either reach a point where durability becomes a problem, or the storage media just can't get any smaller(already at or below 34nm).
 

Device Unknown

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I was thinking more about this. If this holds true "http://en.wikipedia.org/wiki/Mark_Kryder" then even 25% is low. Mr. Kryder details that Hard Disc density doubles every year. Not 25% (compounded or not)
 

soo-nah-mee

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[citation][nom]fstrthnu[/nom]Well Tom's Hardware certainly did their homework here[/citation]This is an except from a book. Scott Mueller did his homework, not Tom's.
 

abdussamad

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Now if only they could figure out a way to recycle hard disks. Just wondering how many drives have been thrown away all these years. Can't be repaired and can't be recycled. Seems a waste.
 
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