Never Underestimate the Bandwidth of a Suburban Filled With MicroSD Cards

toygeek writes "If you've been in IT long enough, you're bound to have heard the phrase 'Never underestimate the bandwidth of a station wagon filled with backup tapes.' These days moving data has become so much easier; We've surpassed baud rates and are into Gbps fiber on the backbones, and even in some homes. So, what's the modern equivalent to this, and what does it take to make the OC fiber connections cringe? Follow along as we theoretically stuff MicroSD cards into a Chevy Suburban and see what happens, and take sneakernet to a whole new level."

Comments

Jet full of CDs

[YttriumOxide]

In my high-school days, we talked about a 747 full of CDs...

I think it may have something to do with growing up on an isolated island nation... there's not many useful places a station-wagon will go.

Re:Jet full of CDs

[JavaBear]

I do recall a story about Maersk moving their data centre from the US to Denmark, using one of their planes as a carrier, filled with harddisks.

This is pointless

[Anonymous Coward]

The original saying was coined in a time where reading from a tape *was considerably faster* than reading over a network. Hence, transferring data via sneakernet was quicker, inclusive of the read-write times.

Now, with multi-gigabit pipes making up the networks, data can be written, pushed, and read again, all at much higher bitrates than reading any storage medium. It's the read-write to physical medium that are the bottleneck with the sneakernet now.

Re:This is pointless

[mooingyak]

Now, with multi-gigabit pipes making up the networks, data can be written, pushed, and read again, all at much higher bitrates than reading any storage medium. It's the read-write to physical medium that are the bottleneck with the sneakernet now.

TFA says that they have 19 million SD cards. If each one is a mid-range 6 megabyte per second speed and we access them all in parallel, that gives 912 terabit per second potential max bandwidth, which almost certainly exceeds any network you're thinking about.

19M card readers (or slots or whatever) probably isn't even necessary.. I'm sure working in rotation you'd have a steady stream of cards whose data was fully read before other cards are even unpacked. I believe the optimal number of card readers would be (time to read) / (time to unpack).

Re:This is pointless

[icebike]

Well, actually not a poor assumption, considering that TFA also indicates that much data is 398,772 3TB hard drives and, moving that much data onto or off of that many drives isn't something that even Google can do in the time period measured. They discounted read-and write times on both media types.

(Although they make no allowance for handling). Its a fun mind game, but as usual a pointless exercise.
The Microsd cards will cost you $855 million dollars, and probably consume the entire production of 64gb cards for a year.

Re:This is pointless

[bored]

That is true for something like SD, but modern tape drives can do well over 500MB/sec in compressed streaming mode, and have native uncompressed capacities of 8.5TB.

That means that even with a midrange tape library with 56 drives, your talking a read/write bandwidth of 27GB/sec (aka 1/3 Tbit/sec). Tape bandwidth scales linearly with the number of drives in the library, and things like the the SL8500 from STK can support up to 640 drives.

It still faster if you have a PB of data you need shipped from NY to LA to write it to tape, put it on a plane and read it back in LA. Plus, it all fits nicely into a big suitcase. Furthermore, even for smaller amounts of data (say 10-20TB a day) the cost of a tape drive and an next day delivery is going to be significantly less than the Gbit/sec or so of bandwidth required to ship a similar amount of data in most places in the US.

Common sense almost prevails

[jlf278]

From the article: "A MicroSD card is only .1 cubic inches, so if all things were equal you could stuff 100 64gb cards into a cubic inch of space! But, that does not seem realistic. In fact it doesn't even seem remotely possible." Perhaps that's because 1 cubic inch = 10 * 0.1 cubic inches and not 100 * 0.1 cubic inches.

Re:Common sense almost prevails

[SJHillman]

They got confused by microSD cards not being one millionth the size of an SD card. Damned misleading names.

XKCD

[Anonymous Coward]

http://what-if.xkcd.com/31/
That is all

The bandwidth of a human.

[queazocotal]

Swallowing capsules containing a terabyte (about 12mm in diameter, and 15mm long of microSDs) is quite plausible.
You can easily swallow a hundred of these, and it'll come out over the next 2 days.
100TB/2 days = 600 megabytes a second.

Re:The bandwidth of a human.

[Anonymous Coward]

Something something memory dump.

Re: The bandwidth of a human.

[davidbrit2]

I've got Crohn's disease, so my ping times are faster.

Calculations omit one tiny detail

[Ygorl]

As they point out in the article, the tremendous bandwidth achieved does not include the logistics or time required to initially copy the data onto SD cards, and then back off of the cards upon reaching the destination. Still, beats a flock of parrots trained in Morse code.

This old chest nut again

[kannibal_klown]

Great, you've managed to transfer X terrabytes of data across state lines. I salute you.

Now... go find this list of files that I need. Also that collection of data that our servers need to process. What, that's going to take you HOW long?

Yes might be quicker to send the data from point A to point B by just shipping disks... but only for archiving purposes. If you actually need to access the data, then you still have that last mile (or 10') of having to load that data into a system or network.

Now, if you were shipping a truck load of servers, or maybe a car full of NAS devices that you could just plug into a network and be done with it... then it's not too bad. Then you can start electronically searching the data within minutes, index it, use it for your data-store, whatever.

But just a car load of disks for non-archival purposes... you're asking for a headache.

A 2014 suburban filled with SD cards

[Arancaytar]

Assuming 2500kg for the car, 0.0005kg per cards, $50000 for the car and $50 per card:

Not only a bandwidth of 68Tbps, but a mass of 12 metric tons (4.8 empty cars).

Also a market value of $0.96B, or the equivalent of 19,141 new cars, plus one car with a broken suspension.

Re:station wagon?

[istartedi]

A station wagon is what moms wanted to drive. Whenever somebody says "Americans want SUVs". They're wrong. The SUV is a legal hack to get around fuel economy standards. See? If we build a station wagon with a center of gravity so high that it tips over in the parking lot, it's legally defined as a truck and we don't have to meet the same standards.

Sorry to get into this, but it's one of my pet peeves. Whenever I hear, "Americans want SUVs" it just grates on my nerves. No we didn't. We wanted station wagons. Mom didn't want to tip the kids over and throw them, her, and the groceries into a ditch. Shortsighted regulators left a loophole in CAFE, and they literally drove a truck through it.

Now all these kids don't even know what a station wagon is. Sounds about right. It's the vehicle that the mom down the block had. I distinctly remember us piling in there with the neighbor kids on more than one occasion, and she smoked like a chimney. Shotgun! I get to ride up front with Mrs. Potter and yeah, it smells up here but we didn't know nothin'. We didn't wear seatbelts and... well... I know this is survivorship bias talking but... we survived!

In other words, get your damned SUV off my lawn.