Hard drive teardown

Bill opens up a computer hard drive to show how it is engineered. He describes how the "head" reads the magnetic information on the disk; reveals how a voice coil motor and a slider controls the position of that head. He also discusses how smooth a disk must be, and briefly mentions a mathematical technique that allows engineers to pack more information on a drive.

[@ExpertCMX]

I love how this man explains with appreciation. This is true knowledge.

[@KenArrari]

It just blows my mind how complicated this stuff is. I can barely even comprehend what's going on, and at some point someone actually sat down and built this stuff. It's beautiful.

[@copperhamster]

Cute little factoid: while the head movement isn't temperature sensitive, the platters are. The cylinders (tracks) are so very tiny in width that the drive actually has to compensate for its internal temperature when moving the heads from track to track. A specific style of failure among a certain brand of drive which I'll not name was for the temperature compensation to go bad, and the drive would work fine for as much as 60 seconds or so and then go into seek seek seek mode because it couldn't find the right tracks. I've recovered data off more than one drive by bagging it up, sealing the entry well, putting it in the freezer, and running it in there, giving me 3-4 minutes to grab data before the drive would fail and needed to cool down.

[@williams6550]

....it couldn't find the WHAT!!?? beep boop error error

[@copperhamster]

there was a show more: right tracks. I've recovered data off more than one drive by bagging it up, sealing the entry well, putting it in the freezer, and running it in there, giving me 3-4 minutes to grab data before the drive would fail and needed to cool down.

[@williams6550]

Copper Hamster That's odd. I did click show more, and that's as far as it got. KZbin dropped the ball and made me look like a fool! Cheers to you, Mr. Hamster.

[@mariusa5754]

+Copper Hamster Yeah I've seen a KZbin video of someone trying to recover data from a HDD, one of the things they tried was putting it in a freezer, it didn't work on their hard drive though. What brand was it?

[@copperhamster]

Marius Ammann Western Digital drives were particularly bad about this failure mode back... oh around 2000-2005 era. So probably that's when and what brand it was.

[@ElectricityTaster]

And one last thing: don't open up your hard-drive like that unless you want to lose all your porn.

[@arbitrage2141]

Evan Ohashi-White I thought it was funny

[@CombineWatermelon]

no not my 30gb of robot hentai!

[@srimatisoren4336]

Please! If you are inspired by this video, don't try to open your hard drive. It is 70% of probability that you will damage your hard drive.

[@anonymoususer3561]

+Srimati Soren *99%

[@williams6550]

70% of the time, you'll damage it every time.

[@NameTheUnnamed12]

Hah you are fool. I unplugged it and poured vodka on it to clean it.

[@torpedo996]

@@NameTheUnnamed12 Slav 100.

[@VoidFame]

I already opened my harddrive a couple years ago and this video makes me want to try and get it running again.

[@Shabazza84]

I'm still mind boggled how an HDD with a head floating nanometers above a rotating surface can survive even the slightest bump or even the normal vibrations of the PC itself.

[@Theunihornable]

Depends on the hard drive itself, the ones used in laptops are far more durable than that of the ones used in desktops because laptops go through more bumps than a desktop. If you were to drop a desktop hard drive while it is spinning, it would be damaged.

[@joeevans84]

Hard drives are a marvel of engineering, perhaps more so than SSD. It's just a shame the advantages of SSD's now make me scoff at the performance and fragility of Hard Drives

[@joeevans84]

***** I reckon it's because once an SSD has an error, that's it for the chip, but if a HD breaks, you can still recover the data off the platters.

[@ProfessorEGadd]

+drthsons Dot Scoff all you like but SSD won't be replacing HDDs in their main application, large scale data centres, for some time. SSD damage themselves too much when rewriting data to be useful in such a demanding application, where billions of read/write cycles are needed and data has to be stable over decades. The relatively small and unchallenging personal computer market is small-fry by comparison.

[@Penguin-kr9do]

I don't think most people care what they use in large-scale operations. Hell, the Government still uses magnetic tapes for some data storage applications. SSDs are rapidly replacing HDDs in home computers, and that's what people care about the most.

[@happmacdonald]

+ProfessorEGadd "Scoff all you like but SSD won't be replacing HDDs in their main application, large scale data centres, for some time." They long since have, friend. SSDs offer magnitudes greater throughput and seek speeds, which are the bread and butter of any high throughput datacenter.. and since we store data redundantly across our storage media to begin with, we just hot swap failed components on whatever schedule we choose. Hell, before SSDs came out we would just RAID together up to a hundred lowest-possible-capacity, highest possible RPM platter drives per SAN, and even then be careful to only use their outermost edges to wring maximal seek speed and IOPS out of them. Now turn that damned music down off my lawn.

[@JohannSwart_JWS]

OK, now build a petabyte storage facility from SSD's only. Firstly, they don't RAID normally like we expect from HDD's. Secondly, their unpredicted failure rates are much higher. Then, there's the budget... Maybe OK for your SAN. Not so much for proper large scale storage.

[@WulinTeo]

I have seen over 100 videos about hard disk ...yet this is the best informative video I have ever seen. It is fun to watch and learn.

[@JarinUdom]

Bill Hammack for President

[@rogertycholiz2218]

Bill is the best - he knows everything!

[@Nhatanh0475]

He should be CEO rather then President.

[@AustinHarsh]

Been in IT all my life, HDDs and Cdroms still blow my mind. :D

[@Zizumia]

Engineerguy just proves to me how amazing humans are. It just blows my mind that someone invented this, people discovered that this method of data works, and fine tuned it.

[@sheilaolfieway1885]

it's really just an advanced tape. a tape used the same concept, magnets.

[@Dennis19901]

@@sheilaolfieway1885 Your easy dismissal of such a concept tells of your ignorance on the topic.

[@sheilaolfieway1885]

@@Dennis19901 Your assumption proves you are a fool.

[@saiprashanth592]

I've had two hard drives that went haywire and opened em both outta curiosity but never managed to get a clean grasp of how it worked. You just cleared that up. Never thought fluid dynamics was used in a hard disc. Thanks a lot for your content. I really appreciate it. Please keep em coming! :)

[@GunsNGames1]

Damn, so simple and extremely impressive at the same time. I got a 1TB one on my PS4 and a 250GB one on my Xbox 360.

[@1metiz]

That clicking at the beginning made me realy nervous

[@sillysad3198]

+1metiz it explains why modern days HDD do not require the "parking" operation, everybody has already forgotten what an improvement it was: autoparking HDDs...

[@fredfindl]

Drives with stepper motor actuators haven't made in years, many of those did require some type of "parking" routine to retract the heads from the media. Since voice coil actuators retract the heads when the drive is powered down, none of that is necessary anymore....

[@unlokia]

How had I not heard of this channel before? Woah! Subbed without a second thought, wonderful, Bill, the best explanation of Winchester drives I have EVER heard on KZbin, and so concise and short. God bless you, thank you, from England :)

[@AIEmporium700]

This is why Illinois has the best education level in the country. We NEED more professors like him all over the world!

[@imadgibbs9063]

Your best video Bill, nicely done

[@dezent]

For everyone outside Liberia, United states and Myanmar... three hundredths of an inch is 0.762mm.

[@HenryKamp]

You are doing a great service to humanity, Mr. Hammek. Thank you for your videos.

[@patrickfreeman8257]

I had my doubts that you could cover this whole topin in 5 minutes but you proved me wrong. Well done, as always

[@keistzenon9593]

would be awesome if there was an ssd video

[@MamboBean343]

+engineerguy So if it picks the most probable option, how come the data is stored reliably? How come the "most probable" is never wrong? Judging by the way you've described it, two distinct series of bits could produce the same magnetic sequence, so how would the hard drive tell them apart?

[@SianaGearz]

There is always a checksum somewhere, for example Reed-Solomon code that allows to restore data where some bits are wrong. Hard drives are not strictly reliable - they are expected to return incorrect data to host once every 50-100 years on average in normal operation, but as you may have noticed, they tend to wear out long before that, for example due to dust ingress, mechanical wear, coil burnout, or power transistor wear (due to thermal degradation, ion motility).

[@ani625]

Another great video Bill. Shows how much scientific research and work has gone into making such precise devices that millions use in their daily lives. The wonder of science never ceases to amaze!

[@pilatevann]

Your videos are always very articulate and informative.

[@Oslokiddo]

when nasa went to the moon they used paper with holes in them as storage. and look at us now. wow!

[@sillysad3198]

+Granbanan > and look at us now. wow! we are incapable of doing a tiny fraction of that that was done with punch-cards.

[@jogrobler]

+Silly Sad Big difference between being incapable and just not having the same priorities. With the private sector getting into space travel (especially SpaceX) there's a very real chance that space travel will finally go where we all hoped it would decades ago.

[@dannyleung2796]

Punch cards and paper tapes are for data and program input only. Data was stored on magnetic tapes.

[@40Sec]

Silly Sad - Haven't seen those pictures of Pluto, have you?

[@BaxterRoss]

Nah dog - core rope memory ;)

[@lopyus]

I took a break from studying remanence, coercivity... etc in physics and clicked on a video which contains that. XD

[@BelowGroundInnovations]

I gotta hand it to you. I LOVE this type of content and you present it in a great way! Keep them coming!! I love to see how things work.

[@Damoclian]

you make such complex machinery much easier to understand, thank you!

[@LazyScoutJace]

Jimmy Fallon should put a "Thank you, Engineers" bit for this instead of dumb thank yous to Caitlyn Jenner or whatever.

[@workhardism]

Correct. Agreed.

[@fartsnstuf]

no thanks, I wouldn't want an unfunny jackass thanking people for actually doing stuff

[@spaceghost8995]

Why are you talking about Fallon ?

[@Sim_Pole]

P-put a magnet in it

[@johnathankrausrig9237]

the harddrive is broken after you applied force on the screws while opening it

[@Theunihornable]

That's why floppy disks would get damaged when you hold a magnet near them. The floppy disk would operate similar to that of a hard disk

[@dave-io]

I was looking for a video to demonstrate the ludicrously tiny physical tolerances in spinning storage, and while I needed to quote Scott Mueller for the majority of the scale-ups, that smoothness analogy was brilliant. Thanks!

[@BlighChannel]

This video is brilliant, it has taught me something that I've been wanting to know for years, I tried asking my physics teacher and his answer was hopless, this video couldnt have been more informative! Thank you engineer guy!

[@DarthSinistris]

More importantly, WHY AM I NOT SUBBED TO YOU???

[@DashRantic]

did you ever figure that out?

[@NinuRenee]

Ooh a Pentium 4!

[@ovalwingnut]

I didn't think I would glean so much info in 5 mins. Thank you.

[@jwexcel]

Thanks for the videos, Bill. Interesting and nicely produced. Good work!

[@kingdavewoody]

so basically a hard drive is like a record player but the record is made of metal and the needle is made of magnets.

[@Matticitt]

Not really. And it depends whether you're talking about CDs or Vinyl.

[@nickrulercreator]

So how about solid state? How do they work?

[@mcjay669]

nickrulercreator it's just flash memory, there's no moving parts

[@PianoScenesMoviesandSeries]

@OldSoulPortal I laughed and spilled my coffee.

[@Kidsvids82]

OldSoulPortal made my day bruh hahaha

[@SianaGearz]

Actually there's always something that does something, else nothing would happen. There are capacitors that store information as charge, and there are FETs (field effect transistors) and when you apply a voltage to the gate of the FET, the conductance between source and drain changes. In fact you can just use the parasitic capacitance of the gate to store information, you energize it, and the voltage on the gate can hang around for a very long time! I think this is how flash works.

[@justpassnthru]

*I* 's and *O* 's

[@lolmhao]

This is an amazing video. Really helped understanding how everything works

[@RapidGamingStudios]

I must say, I enjoy these videos a lot and learn more about computers than i ever would in a class. Thanks.

[@BunnyRaptor]

"A home computer must store data reliably to work well or else it's pointless. Enter the Chromebook.

[@ahall9839]

Which still needs to store data reliably to work well. It doesn't just magically teleport the internet onto the screen.

[@powder-phun949]

but... how can you change a single bit in a sequence? let's say i have: > > < < >, which is: 0 1 0 1 if i would like to change it to 1 1 0 1 i would have to rewrite everything after the first zero, not only it: > < > > < 1 1 0 1 how is this done? is every byte separate, so i can rewrite only it, without affecting anything else? Anybody knows?

[@powder-phun949]

but if my change would in the middle of that sector, I would have to change almost 2000 bits?

[@powder-phun949]

***** So basically you just don't change a single bit? That makes sense. it's easier to just move the changed data to a new sector. Right?

[@powder-phun949]

Got it.

[@Makbeefy]

Love ya, Bill. Keep up the great work. This video was well-presented, interesting, and VERY informative. Thanks!

[@klesstwo]

How could you possibly dislike something remarkable like this..

[@PeteRoy]

Now do a video about how SSD work

[@9000888sora]

I dont think he has the expertise to explain it. Theres not an easily explainable answer for them as they have many more variables. Modern SSDs use nandflash and microcontrollers. But point is they're a lot more complex.

[@Mex1CanJack]

Dat red shirt, tho.

[@paraseth]

Simply amazing! I am a physics postgraduate. I know the physics, but to see the use of this in hard drive is wonderful

[@Logarhythmic]

This is an incredible video for an incredible piece of technology. More please!

[@XequlixX]

somebody is copying your video 4iaxOUYalJU

[@MadSparks164]

He has released this video under the creative commons licence - Meaning reuse is allowed, as long as credit to the original author is given. The channel in question has stated the 'source video' as belonging to engineerguy, and has made no attempts to cut his outro - Legally and ethically, this is fair play.

[@Saral451]

So basically my porn collection is just 1's and 0's.

[@lolioliol360]

+Saral451 and any profile youve made or videos youve watched or friends pictures youve seen or messages youve sent.

[@thedocumentarian7259]

+Saral451 Hot or not.

[@kingdavewoody]

+Saral451 1's are dicks and 0's are the things that dicks go in

[@LaplacianFourier]

How is that different from penises and holes?

[@williams6550]

1+0=good; 0+0=good; 1+1=not so much.

[@marianaperez4641]

Amazing! I like the way he explains it. Is good to know how the hard drive works and his the function.

[@alphabeets]

Awesome video. I always love to see a new one posted. Thanks.

[@opfinderHarald]

Metric dude. Dont you engineers use metric?

[@Xanifur]

nm is metric, he just used the football field as an example for us 'murricans.

[@opfinderHarald]

Well as he sad, "american or european football field" and wrote how many yards an european and an american football field is, he uses imperial measures. And when he describes how smooth it is, he says that enlarged to a football field there would be less than 1/300 of an inch (imperial again) difference in the elevation of the field. And of course nm is a metric unit, but he is probably using nm because it sounds stupid to say "the head floats around 0.00000009843 inch over the metal disk"

[@you238]

Engineers are pragmatists and use whatever unit is appropriate or they grew up with. Usually they can get away with it because they're talking to fellow engineers that are intelligent enough to understand whatever unit they choose to use.

[@uberLejoe]

He's an American, he was raised imperial... It's how we speak, it's in our euphemisms, deal with it...

[@ib9rt]

Harald Togram Units of measure are like languages. Just as it's good to speak different languages (English, Spanish, German, French...) it's also good to be fluent in different units of measure (joules, calories, BTUs, ...). Engineers are able converse in different technical "languages" and translate between them.

[@SamieOld]

Thanks, this always fascinated me how many trillions of bits of information may be condensed like this!

[@lichto2005]

EXPLAIN EVERYTHING IN MY HOUSE TO ME! Your content is so intriguing, and even though the material in itself is not super entertaining, the polished look makes me enjoy learning about it. Love it.

[@AdultsSwim1]

Have you considered making this into a television show? I would watch every episode! :) Your ability to cover very fascinating subjects and break them down so anyone can understand them impresses me. Keep up the great work! I look forward to your next video.

[@50centgotshot9times]

It completely blows my mind how people have discovered how to create such complex machines as well as things like space exploration as well as many many more scientific and engineering inventions and discoveries.

[@MyKolbe]

Love your movies - short and still quite accurate and detailed. Keep it up!

[@Matttix]

It just blows my mind how any human being can consider this not interesting. It's so amazing it moves me, like art.

[@mariandreemorales886]

Its amazing to see how the hardrive of the computer is and how it works because most of people doesn´t pay attention to this, but without the hardrive the computer couldn´t work well. It is difficult to understand all this stuff but this video helped a lot. Its incredible how a very small box can make a computer work well. It was amazing to know how this worked.

[@jehot1]

The exact kind of explanation I was looking for. Great!!!

[@Flashtone08]

Bill, wonderful videos! best series on youtube!

[@NoelMacaldo]

I'm an engineering student and I love all your vids!

[@henik9]

Wow you are amazing at explaining complicated things. Bravo sir!

[@balajijohnson6580]

God.....he should be having 50 million subscribers right now....for his work and knowledge

[@craigmoritz]

Finally, an educational program that shows the math. No math=Casual conversation, Math=science!

[@LORDFARQUAADIUS]

Great explanation. Thank you!

[@almandinefox5160]

the sound of it spinning is so nostalgic

[@stevemadison7895]

Absolutely incredible! Your explanation is clear but trying to imagine proposing this original idea and not being laughed off the planet is difficult. How they made the thing work has got to be a story in itself!

[@dfs-comedy]

Those voice coil magnets are crazy-strong (the better to move the head quickly, I guess.) I have a number of old hard drives that had confidential customer information on them, so I took the platters out and use them as coasters, and I took out the voice coil magnets to use as fridge magnets, before sending the rest for recycling. The magnets can hold 50+ pages to the fridge at once. Great video!

[@voidofdeath]

So much complexity behind this 'little box' in our computer. Very well explained. Informative. Thanks. I sub.

[@stogielicious7463]

the world needs more people like this guy

[@DigitalESP]

This is a really great video, thank you Bill!

[@ibrahimalowonle9106]

These engineers dont get enough credit. This is absolutely amazing technology. God bless those brilliant engineer minds.👏👏👏👍

[@thethreemusketeers1550]

This was very useful, I didn't realize just how closely linked physics and computer science was. Thanks for helping me understand.

[@subzeroicefrost]

+The Three Musketeers Computer Engineering *

[@sebastianos1]

Very nice ! I use this device every day and now i know exactly how it is working! Thank you very much :)

[@nebula2933]

Now consider that all of this amazing innovation has had 9 WHOLE YEARS to progress even further since this video was uploaded.

[@Je7k9b8]

Very enlightening, thanks Bill. Not only am I impressed with such precision and ingenuity, there also lingers a peculiar sense of wonderment and uneasiness when I reflect upon the elemental properties making it possible. I am infinitely curious about our universe, natural laws & interplay of energy/matter & space/time constituting all we can observe and the "so much more than we can't".. (yet). The uneasiness stems from the latter due to my short lifespan, I'll never know enough to be satisfied.

[@deemon710]

Really nice explanation. Thanks!

[@Gulthok]

Great video! Incredibly interesting and intriguing stuff for the layperson to watch!

[@RoiAtalla]

Ah, really awesome video! This video was very well made and your voice was perfect for this. Being a programmer and a "techie", I've always wanted to know the exact workings of a hard drive. The hard disk drive may very well be the most amazing thing humans have ever created, maybe followed closely with the CPU.

[@yourfullofsheite]

Nicely done! Complex information put simply.Gives me the illusion of feeling smart, and the knowledge I am a little less ignorant

[@Kazahmish]

Great video, I remember the first time I saw a hard drive apart, well.. it was my brand new 1gb hard drive, we had a power surge and it fried my computer and everything in it.. so I took the hard drive apart, still clueless until today HOW it worked, I was amazed at the insides.. for about 10 min until I got my 20 lb sledge hammer.. I was still picking up pieces of it 3 years later and each time I thought I had everything.. thanks again Bill..

[@ss33988]

ones again, thank you for posting great informative videos

[@jw5895]

Brilliant, love your work.

[@Drizzt1343]

make more videos! this is so fascinating i love finding out how stuff works!

[@trueopsimath]

The old IBM System 36 (a mid-range, mainframe-type machine) hard disk units had a clear plastic cover and they were arranged so that you could open up the door to the back of the main unit and watch it work. It was a selling point. After all, if the company spent a ton of money on a computer system, the execs wanted to be able to see it doing something -- even if they had no idea what they were looking at. I used to love to show off the machine back when PCs still just had floppy drives. I would kick off a really disk-intensive program, then open up the back of the cabinet so my friends could watch it work.

[@FeelYourMind]

The read/write head is actually so close to the platter that a smoke particle can't even get between the two. Amazing!

[@Finstatube69]

you sir are the best tech explaining guy on youtube. we want more :D

[@TestingPyros]

I love the aerodynamics! What an AMAZING idea!

[@rayman4449]

Excellent videos as ususal. Fascinating!

[@daveslady57]

Back in 1984 I worked for Ampex Corporation in their hard drive division. We were given the basic discs (substrate) and ground the surface with a diamond tip to a mirror surface. I remember the surfaces had to be absolutely perfect, and if you accidentally got a bit of saliva on it blowing off any dust you'd have to regrind it. The measurements for thickness of the disc was crucial as well.

[@AustinSpafford]

Oh man, I didn't know this was one of Bill's videos until I heard the intro music. Great theming!

[@DJVADO17]

i had no idea that so much engineering went into such a simple tool...wow! +1 sir

[@burtlade1705]

Thanks Bill! I have not yet seen one of your videos that I didn't like.

[@iWinRar]

Thank you for a new episode. Been waiting

[@Dellyeoman]

Great video. Fascinating stuff.

[@Masterr59]

Liked and Favorited. I love this stuff! He is right... we take these things for granted soo much. And I love learning about this stuff. How someone could make something so reliable for so many years... storing all these files and re-writing thousands and thousands of times... and still working hard. One of our computers is 8 years old and still doing it!

[@baerabas]

as always, very very informative and great videos! thank you!

[@bk8]

Impressive video. I remember one of my lecture where we were told the precision needed to write a bit is comparable to landing a plane on a stamp!