How do hard drives work? - Kanawat Senanan

Translator: Matej Divjak Reviewer: Nika Kotnik

Imagine an airplane flying one millimeter above the ground

Predstavljajte si letalo, ki leti en milimeter nad tlemi

and circling the Earth once every 25 seconds

in vsakih 25 sekund obkroži Zemljo,

while counting every blade of grass.

pri tem pa prešteje vse travne bilke.

Shrink all that down so that it fits in the palm of your hand,

Če to pomanjšate do te mere, da se prilega vaši dlani,

and you'd have something equivalent to a modern hard drive,

dobite nekaj enakovrednega sodobnemu trdemu disku,

an object that can likely hold more information than your local library.

predmetu, ki lahko vsebuje več informacij kot vaša lokalna knjižnica.

So how does it store so much information in such a small space?

Kako pa lahko hrani toliko informacij na tako majhnem prostoru?

At the heart of every hard drive is a stack of high-speed spinning discs

V središču vsakega trdega diska je skladovnica hitro vrtečih se plošč

with a recording head flying over each surface.

z bralno/pisalno glavo, ki leti nad vsako od površin.

Each disc is coated with a film of microscopic magnetised metal grains,

Vsaka plošča je prekrita s prevleko mikroskopskih magnetiziranih kovinskih zrn

and your data doesn't live there in a form you can recognize.

in vaši podatki tam ne živijo v obliki, ki bi jo prepoznali.

Instead, it is recorded as a magnetic pattern

Namesto tega so zapisani kot magnetni vzorec,

formed by groups of those tiny grains.

ki ga tvorijo skupine teh drobnih zrn.

In each group, also known as a bit,

V vsaki skupini, znani tudi kot bit,

all of the grains have their magnetization's aligned

imajo vsa zrna magnetizacijo poravnano

in one of two possible states,

v eno od dveh možnih stanj,

which correspond to zeroes and ones.

ki ustrezata ničlam in enicam.

Data is written onto the disc

Podatki se na disk zapišejo

by converting strings of bits into electrical current

s pretvorbo bitnih nizov v električni tok,

fed through an electromagnet.

ki ga dovaja elektromagnet.

This magnet generates a field strong enough to change the direction

Ta magnet tvori polje, ki je dovolj močno, da spremeni smer

of the metal grain's magnetization.

magnetizacije kovinskih zrn.

Once this information is written onto the disc,

Ko so informacije enkrat zapisane na disk,

the drive uses a magnetic reader to turn it back into a useful form,

pogon uporabi magnetni bralnik, da jih pretvori nazaj v uporabno obliko,

much like a phonograph needle translates a record's grooves into music.

zelo podobno gramofonski igli, ki utore na plošči prevaja v glasbo.

But how can you get so much information out of just zeroes and ones?

Toda kako lahko dobimo toliko informacij iz samo ničel in enic?

Well, by putting lots of them together.

Tako, da jih damo mnogo skupaj.

For example, a letter is represented in one byte, or eight bits,

Na primer, črko predstavlja en bajt ali osem bitov,

and your average photo takes up several megabytes,

vaša povprečna slika pa zavzame več megabajtov,

each of which is 8 million bits.

vsak od njih pa ima 8 milijonov bitov.

Because each bit must be written onto a physical area of the disc,

Ker mora biti vsak bit zapisan na fizični del diska,

we're always seeking to increase the disc's areal density,

venomer iščemo načine za povečanje gostote zapisa na disku

or how many bits can be squeezed into one square inch.

oz. koliko bitov lahko stisnemo na kvadraten palec.

The areal density of a modern hard drive is about 600 gigabits per square inch,

Gostota zapisa modernih trdih diskov je okoli 600 gigabitov na kvadratni palec,

300 million times greater than that of IBM's first hard drive from 1957.

300-milijonkrat več kot pri IBM-ovemu prvemu trdemu disku iz leta 1957.

This amazing advance in storage capacity

Ta neverjetni napredek v kapaciteti shrambe

wasn't just a matter of making everything smaller,

ni bil rezultat le pomanjševanja vsega,

but involved multiple innovations.

ampak je vključevalo številne inovacije.

A technique called the thin film lithography process

Tehnika, imenovana proces litografije tankega filma,

allowed engineers to shrink the reader and writer.

je inženirjem omogočila pomanjšanje bralno/pisalne glave.

And despite its size, the reader became more sensitive

In navkljub svoji velikosti, je bralnik postal bolj občutljiv

by taking advantage of new discoveries in magnetic and quantum properties of matter.

z izkoriščenjem novih odkritij na področju magnetnih in kvantnih lastnostih snovi.

Bits could also be packed closer together thanks to mathematical algorithms

Biti so lahko bili tudi bolj zgoščeni zahvaljujoč matematičnim algoritmom,

that filter out noise from magnetic interference,

ki filtrirajo motnje magnetne interference

and find the most likely bit sequences from each chunk of read-back signal.

in najdejo najbolj verjetne bitne nize iz vsakega kosa povratnega bralnega signala.

And thermal expansion control of the head,

Nadzor nad termičnim raztezanjem glave,

enabled by placing a heater under the magnetic writer,

ki ga omogočimo z grelnikom pod magnetnim zapisovalnikom,

allowed it to fly less than five nanometers above the disc's surface,

ji je omogočilo lebdenje na manj kot petih nanometrih nad površino diska,

about the width of two strands of DNA.

kar je približno širina dveh vej DNK.

For the past several decades,

Zadnjih nekaj desetletij

the exponential growth in computer storage capacity and processing power

je eksponentna rast kapacitete računal- niškega pomnilnika in procesorske moči

has followed a pattern known as Moore's Law,

sledila vzorcu, ki ga poznamo kot Moorov zakon,

which, in 1975, predicted that information density would double every two years.

ki je 1975 predvidel, da se bo gostota informacij podvojila vsaki dve leti.

But at around 100 gigabits per square inch,

Vendar pa je pri okoli 100 gigabitih na kvadratni palec

shrinking the magnetic grains further or cramming them closer together

nadaljnje pomanjševanje magnetnih zrn, ali njihovo še večje tlačenje skupaj,

posed a new risk called the superparamagnetic effect.

predstavljalo novo tveganje imenovano super-paramagnetni učinek.

When a magnetic grain volume is too small,

Ko je prostornina magnetnega zrna premajhna,

its magnetization is easily disturbed by heat energy

njegovo magnetizacijo zlahka zmoti toplotna energija

and can cause bits to switch unintentionally,

in lahko povzroči, da se biti nenamenoma zamenjajo,

leading to data loss.

kar vodi k izgubi podatkov.

Scientists resolved this limitation in a remarkably simple way:

Znanstveniki so to omejitev rešili na presenetljivo enostaven način:

by changing the direction of recording from longitudinal to perpendicular,

s spremembo smeri zapisovanja iz vzdolžne v navpično,

allowing areal density to approach one terabit per square inch.

kar je omogočilo gostoto zapisa blizu enega terabita na kvadratni palec.

Recently, the potential limit has been increased yet again

Nedavno se je potencialna meja ponovno zvišala

through heat assisted magnetic recording.

z uporabo toplotnega magnetnega zapisovanja (HAMR).

This uses an even more thermally stable recording medium,

Ta uporablja še bolj termično stabilen zapisovalni medij,

whose magnetic resistance is momentarily reduced

čigar magnetno odpornost se za trenutek zniža

by heating up a particular spot with a laser

s segrevanjem določene točke z laserjem

and allowing data to be written.

in omogočenim zapisovanjem podatkov.

And while those drives are currently in the prototype stage,

In medtem ko so ti pogoni trenutno v fazi prototipov,

scientists already have the next potential trick up their sleeves:

imajo znanstveniki v rokavu že nov potencialni trik:

bit-patterned media,

medij bitnih vzorcev (BPM),

where bit locations are arranged in separate, nano-sized structures,

na katerem so lokacije bitov razvrščene v ločene nano strukture,

potentially allowing for areal densities of twenty terabits per square inch

kar potencialno omogoča gostote zapisa 20 terabitov na kvadratni palec

or more.

ali več.

So it's thanks to the combined efforts of generations of engineers,

Zahvalimo se torej lahko skupnim prizadevanjem večih generacij inženirjev,

material scientists,

znanstvenikov snovi

and quantum physicists

in kvantnih fizikov,

that this tool of incredible power and precision

da se to orodje neverjetne moči in natančnosti

can spin in the palm of your hand.

lahko vrti v vaši dlani.