How Heavy Is a Petabyte? 495
Posted
by
timothy
from the but-electrons-don't-weigh-anything dept.
from the but-electrons-don't-weigh-anything dept.
Jon Morgan writes "Whilst heaving around numerous data storage systems to sell (they weigh A LOT!), we got to wondering: How heavy is a Petabyte of data storage? Our best guess is 365KG, which is 6 million times lighter than in 1980! But is there a lighter way to store a Petabyte?"
MicroSD (Score:5, Informative)
Re:Need conversion to units of Libraries of Congre (Score:2, Informative)
Re:library of congress (Score:5, Informative)
Re:Cloud computing-Clouds in Elephant Units (Score:5, Informative)
A common misconception, and just saying it on Slashdot doesn't make it true. Clouds weigh more than elephants - much more. In fact, you can learn the weight of clouds in elephant units here. [wsi.com]
Not only that, but clouds are usually darker than the air around them.
Re:or 2.5" drives? (Score:4, Informative)
My problem with the assessment however, becomes even more glaringly obvious when you look at the micro SD proposal in the grandparent. If you are going to have a single SD card reader and plug these cards in as needed, the weight estimate is ok. If however all 1 PB of data must be immediately available to your software, the weight gos up dramatically.
In the case of 3.5" SATA HDDs, that weight/cost should include a storage system that renders all the data available at the same time. 140 Lbs for 48 Hard drives is reasonable. [sun.com]
Depending on your RAID Level, 1,500 Lbs per petabyte is closer to reality. 1,700 Lbs to 2,000 Lbs per petabyte if you add the rack to the equation.
BTW: Doing something sane, like RAID, instead of JBOD or RAID 0, will increase that mass somewhat.
Re:Cloud computing-Clouds in Elephant Units (Score:4, Informative)
Air also weights more than elephants.
In fact, every square meter of the world has 2 elephants of air on top of them.
So "missconception" my ass.
Re:Minimum mass of a Petabyte (Score:5, Informative)
For example, it seems to me like a "full" drive seems to physically weigh more than a blank one, sort of like a full battery is noticeably heavier than an empty one.
Wrong on both counts. A "full" magnetic hard drive platter just has its magnetic domains aligned in a certain pattern.
Those domains are physically there whether they are used for data storage or not. So the weight will be indentical.
A battery does indeed become lighter when "emptied" - according to E = mc^2 and the energy that came out of it.
However, this is way, way, way under anything you would be able to notice.
An AA alkaline battery can deliver about 10000 Joules (http://www.allaboutbatteries.com/Energy-tables.html [allaboutbatteries.com]) - so
a discharged (= "empty") AA alkaline will weigh m = E/c^2 or roughly 10^-10 grams [google.com] less than a charged one.
That's 0.1 nanograms. About 100 human skin cells. No, you won't notice that.
Re:Need conversion to units of Libraries of Congre (Score:3, Informative)
I've seen stats that all the books ever written by mankind add up to 50 PB of data storage. Presumable unZipped :)
You've seen ESTIMATES.
Re:There is a way! (Score:5, Informative)
Insightful? Assuming you can perfectly remember 1 byte per second, you'd be memorizing for over 100 million years. The human brain is great and all that, but no way are you going to store that much data while being able to reproduce it later.
Re:Minimum mass of a Petabyte (Score:5, Informative)
That was my dissertation topic, conventional systems require ~kT per bit (k is the Boltzmann constant = 1.3806503 Ã-- 10-23 m2 kg s-2 K-1 and T is the temperature of the gate in Kelvin) for each read. Quantum systems can access well below that by various trickery (single photon optical computers can reduce this by a thousandfold). In theory a individual photon can hold huge amounts of data in it's state vector before collapse. The trick is making a measurement on enough of these photons to extract the info you need while overcoming shot noise.
Re:Cloud computing-Clouds in Elephant Units (Score:2, Informative)
A common misconception. Weight is not mass. [wikipedia.org]
Air also has mass, not much different from the mass of cloud (which is mostly air).
Re:Need conversion to units of Libraries of Congre (Score:3, Informative)
51.2 LoC's
Assuming LoC is still = 20TB
Re:or 2.5" drives? (Score:3, Informative)
Re:Cloud computing-Clouds in Elephant Units (Score:3, Informative)
Here's the one that'll really get you:
A pound of feathers weighs more than a pound of gold.
Re:A lot heavier than... (Score:4, Informative)
Well, a rough check shows that each base pair (and backbone) weighs about 614amu, which gives a weight of 10^-21 grams for 2 bits. So, pure DNA weighs about a 4ug per petabyte, supposing my calculations are correct.
However, that's hardly fair. The density of bits is _far_ from the density of the actual storage. After all, a hard disk uses only extremely small regions (probably only a few million amu) on the surface of a disk. However, the motors, the case, and even the disk (substrate) itself are orders of magnitude heavier than the bits themselves. I'd be rather surprised if the actual storage was much more than a couple grams.
The point is, of course, that there are all kinds of ways to store data, but when it comes down to weight, the control mechanisms are what matters. For this reason it's extremely unlikely that DNA will _ever_ be used as storage, except if we start making bio-computers.
Also, for what it's worth, the human genome only stores about 770MB, only a bit more than a CD.
Re:Cloud computing-Clouds in Elephant Units (Score:3, Informative)
Re:library of congress (Score:3, Informative)
Re:library of congress (Score:3, Informative)