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Comment by guidedlight | Hacker News Reader

If you want to blow the mind of a non-tech person. Show them a high capacity MicroSD card and tell them how many 1’s and 0’s it can reliably store.

A 2TB MicroSD card really is a modern marvel in engineering.

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Depending on if they are old enough to remember floppy disks, tell them the tiny card holds as much information as almost 1.4 million 3.5 inch floppy disks (assuming 1.44mb each). If you pile those up, it would be about 4.5 km high. Or if you take the 720kb kind, your pile would be as high as Mount Everest.

Holy shit that’s a great way of putting it.

I’m not double checking the math but that’s insane, 1.4 million, insane.

I am old enough to have used 5 1/4 inches floppies on PCs running MS-DOS, 3" microdrives on ZX Spectrum 3+, and tapes on Timex 2068.

One of my teachers broke the compilation record of compilation submissions per day, on the computing center, with punched cards.

On my first trip to a computing center of the post office during high school, they still used punched tape.

The modern SD cards are indeed a wonder.

Yeah this is the corollary to "use boring technology" - at some point, jump.

They could put the capacity of every 3.5" floppy ever made in a suitcase full of microSD cards.

A wild guess of 3.5" floppy production is 30B. So you need 21,428 2TB micro SD cards. A 15mm x 11mm x 1mm you need 3 1/2 liters.

The bandwidth of a station wagon hurtling down the highway grows every year.

Sneakernet remains undefeated. https://what-if.xkcd.com/31/

>> "A solid-state laptop drive weighs about 78 grams and can hold up to a terabyte."

Amazing how we went from 1TB 2.5 inch drives to 8TB m.2 drives and 2TB microSD cards in 11 years. And it would be more like $7k in 4TB drives than $130k. Put $130k of modern drives in the same shoebox and you're probably into the petabyte range. Go to the then-top of the line microSD milk jug and it's getting up there with these 2TB cards.

I had estimated 10^11.

"I could have a bodycam record everything that happens to me for a whole month, 24/7, in high-definition and store it on something smaller than my fingernail."

HD (1080p) video @ 30fps is from 130-149MB/sec

2TB / 149MB = 13,422 minutes == 223.7 hours == 9.32 days

I'm being facetious of course but I was surprised by just how much storage space I needed to record security cameras. I have a mix of 4k & HD, and 10tb doesn't even get me a month of 24/7.

YouTube’s 1080p is 5 megabits per second, not 130 megabytes per second.

So 2TB lasts 37 days, meaning blowski is right.

Of course powering that bodycam will be a different matter.

Of course this is all academic: the file size depends on the codec, ie how much you want to trade power for space. YT/Netflix/etc obviously trade for file size very well. But a body-worn device isn't as capable.

Take the Axon Body 2 as an example, the gold standard for police bodycams. According to its specs [0] it'll record 12 hours of 1080p video on its 64GB internal storage.

So using H.264 it produces 64gb/12hr == 5.333 (repeating of course) GB/hr, making 2TB / 5.333GB == 375 hours, or about 15.625 days

[0] https://s3-us-west-2.amazonaws.com/cms-nppgov.resources/app/...

Video compression. Another separate modern marvel of mathematics.

Not sure what security cameras you’re using, but mine all use H.264 1080p compressed streams. I get about 15 days worth on a 2TB spinning rust across 6 cameras.

Even going by your own numbers, you almost certainly are using compression too. 9.32 days on 2TB does not get you a month on 10TB if you “have a mix of 4K & HD”.

Indeed. I use Unifi cams, 3x4k & 5x1080p, they use h.264. My system's current estimate is 19d 20h 37m of recording.

I really wish they enabled h265

What cameras are you using?

This seems like it would work, but the average person has no idea how high mount Everest is. My favorite way of explaining it is when I was looking at Mount Olympus from the beach, and said "you see the mountain? If you stack two more Olympuses on top of that, it still wouldn't reach Everest".

Another way: taking the 720kb variety floppy, if you lay them side by side it would form a line of 250km in length. Or in other words: driving at highway speed, it would take 2 and a half hours to drive by all the floppies it would take to store what one of these new micro SD card can hold.

Oh I love that!

Then again you never look at Mt Everest from sea level.

Technically true, but the base of Mt Everest is at 5100 meters, which makes it a lot less impressive. The entirely Himalayan range is sitting two vertical miles above sea level.

On the other hand, those discs would barely fill a 40-foot container. I think that's quite close to what people would intuitively expect.

Or tell them if you wrote 0s and 1s on a paper tape, for 2TB of data, you would need a tape as long as the distance between the Earth and the sun. (9mm or a third of an inch per digit)

Okay, I'll byte. Imagine a game of Tetris where each block is a byte of data. With a 2TB card, you'd be playing until the heat death of the universe – and still not see the Game Over screen.

I have a frame of various media over the years over my desk including a 5.25" floppy, a 3.5" floppy, ZIP disk, CD, Blu-Ray, SD, microSD, etc.

As a technical person, my mind keeps getting blown.

No Jaz drive?

That’s a really nice idea. Maybe I will steal it :)

It's a fantastic and quick project!

I use two layers of thin black foam. The top layer of foam sheet has cut-outs for the various types of media except microSD card, which is held in place with a small dab of glue. They're pressed against the glass and has survived 2 moves without issue.

That doesn't mean much though.

How about when you tell them it can store 38 seasons of TV shows in HD?*

Or 40 dual-layer Blu-Ray discs?

Does it seem like a lot or a little?

*Assuming 4 GB per 60-min drama episode in 1080p, and 13 episodes/season, all of which is pretty ballpark.

with most laypeople streaming, they don't really have a sense of how much space a season of tv shows is. you need something more relatable, like photos

There was a thread here the other day about how everyone just streams everything, and nobody knows what a file is any more. Why would someone know how big a photo is? They're all on Google anyway.

not everyone has google/icloud sync on. people run out of space on their phones all the time.

I think the obvious Americanized measurement here is "number of football fields covered by 4x6 photos".

Or almost 1 copy of the Oppenheimer director’s cut

Wait, if one microSD card holds more than a year's worth of TV shows for an average person, does that imply paying $10/month for unlimited streaming is a really stupid idea? Granted it's not about paying for the recording medium, but still.

I hate to be a cynic on this one, but I never found micro SD cards reliable enough to store anything longer than absolutely neccessary. Usually that is until I can move the data to a better storage medium. The tech that runs on these devices is incredibly cursed, and keeps changing very fast.

30C3 had a fun talk about the internals of mSD cards.

https://media.ccc.de/v/30C3_-_5294_-_en_-_saal_1_-_201312291...

I remember showing my grandfather a Commodore Amiga playing a Genesis song from a 3.5" floppy disk [1] and he just said: "yes, it is just recorded on the disk". I tried to explain the complexity (digital to analog processes) of this but he just abstracted the idea thinking in other media like LPs, Casettes, and the new CDs.

[1] https://youtu.be/_UnVy9w0xKk?si=kFwgo1qU6Dw9Y6sY

Haha, I had a copy of that disk back in the day, but I certainly haven't thought of it in the last 30 years. Thank you for reminding me! While it was a bit of a marvel to put an entire pop song onto an 880k disk, the not-so-hifi sound quality was already apparent back then. I guess they forgot to switch off the low pass filter by turning off the power LED.

Thank you for teaching us abot the low pass filter! I searched that after your message since I was not aware: https://groups.google.com/g/comp.sys.amiga.audio/c/6wBXmBoOI...

On the other hand, I just learned from your link that there apparently were A500s where the low pass filter could not be switched off in software. AFAIR, toggling the LPF in software was already possible in the predecessor, the A1000.

Anyhow, coupling the LPF to the power LED (and having a software controlled power LED in the first place) is a very Amiga thing to do. It's one of the platform's many nice idiosyncrasies.

Should have shown him a tracker :)

> tell them how many 1’s and 0’s it can reliably store.

Zero.

On the largest capacity, you're at least not getting a card with tons of remapped sectors where half the flash has already died.

Reliable? 0. Sdcards are not reliable

I was using one for filming a client job the other day, without a backup card. It cracked and bent in half and I thought I was going to have to entirely reshoot the location. Bent it back and put it in the laptop and got all the data fine. Never had one fail.

If you've never had one fail you haven't used them enough. Raspberry Pi usage seem to be pretty efficient at sorting the good ones from the bad ones

I've been using RPIs since their first release and never had an SD card failure. Might just be luck though cause I know the problem is real and happens to many people.

It depends on the distro. What especially hammers SD cards on Linux, eventually rendering the card read-only, is logs being written to disk. A lot of distros for Raspberry Pi therefore now keep logs in RAM.

This issue is true of any flash memory. See my sibling comment on using an USB stick to write data: I also destroyed a bunch with logs

I destroyed many SD cards with the original Pi. I ended up putting the card read only with the hardware switch and use a USB stick for writing data. No issue with microSD cards with more recent Pis (or other SBC) however

Exactly my experience. They work five until they don’t.

Not risking my data nor tribe in those things anymore even though I love that they’re small and cheap. Ideal for large media which doesn’t require too much bandwidth.

tribe=time

> It cracked and bent in half

You cracked and bent a microSD card? How did that happen?

Chewbacca

I'm surprised there aren't adapters to connect two or more micro SD cards to one device and duplicate written data to both of them. I assume you couldn't do it with wiring alone, and would need a chip in there.

Even finding a microSD extension was tricky when I wanted to mess about with the hardware.

Even better, if you want to blow the mind of even most tech people, show them a high capacity MicroSD card and tell them how many 1's and 0's it can REALLY store.

SD cards are many, many times larger than you think they are - often hundreds of times larger. This is because they use wear leveling to avoid read/writing too much to any one bit.

It is quite possible that this one SD card could have hundreds of TB of storage space on it. I have often wished there were some easy way to access all of this space for situations where you know that you only want to write once to the card - meaning you know you only want to write once. Would be great for storage.

No, not hundreds of times larger. Maybe ~5% larger.

It sounded extremely improbable to me, so tried googling and I wasn't able to find anything that would back up such claims. Can you provide a source for the information that MicroSD cards have more than e.g. double total physical capacity?

Not double, but having extra space than the device is rated for is listed as a wear leveling technique.

https://en.wikipedia.org/wiki/Wear_leveling?#Techniques

The number of 1’s and 0’s is lower than the US national debt, which is kind of bonkers.

The US debt is currently around 271 terabits [0].

[0] https://en.m.wikipedia.org/wiki/Bit_(money)

I remember many years ago when my uncle explained to my grand dad how many photos he could fit in his cameras memory card. He was completely blown away, he couldn't believe it, he said it was impossible and laughed.

If you want to blow the mind of a tech person, tell them how long it will store those 1's and 0's ... (~10 years max, flash doesn't hold it's contents over time)

In case anyone else was wondering what the number is: 17,592,186,044,416 bits. On a durable card that is smaller than a stamp.

Sounds bigger than saying 2^44

I think you both have fallen for the bullshit marketing of storage manufacturers who want you to think you're getting 16 terabits of capacity. You're not. You get 16,000,000,000,000 bits.

Oops, I mean tibibits.

If we are really going to get technical we’d need to determine how much over provisioning the card is designed with.

how many can they store?

Approximately sixteen trillion. I suspect that number is not really comprehensible to a large population though.

so the grains of sand on TRAPPIST-1e

It’s enough to store the name of every human being that has ever lived.

This video helped me visualize how big of a number 1 trillion is:

https://www.youtube.com/watch?v=PoOJggESR8o

Current US debt is almost 34 trillions? https://www.usdebtclock.org/

So the debt is just a bit more than two of these microSD cards' worth of storage! I might have the unit conversion wrong, though.

If you were to count those at a rate of 1 per second, it would take about half a million years.

16,000,000,000,000

1 Byte = 8 bits

1 KByte = 8 * 1000 = 8 000 bits

1 MByte = 8000 * 1000 = 8 000 000 bits

1 GByte = 8000000 * 1000 = 8 000 000 000 bits

1 TByte = 8000000000 * 1000 = 8 000 000 000 000 bits

2 TBytes = 8000000000000 * 2 = 16 000 000 000 000 bits

All values approximate.

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