### ZFS: Boils the Ocean, Consumes the Moon

ZFS (aka: Zettabyte Filesystem), Sun's newest filesystem that will ship with an update of Solaris 10 in 2005, can address 128-bit filesystems! Let's explore how insanely huge this is from various perspectives. http://wwws.sun.com/software/solaris/10/ds/zfs.jsp

First, I've heard several times now that to construct/power a storage farm of this size would boil the world's oceans. Is this just hyperbole? Presenters typically say something like: "someone in engineering ran the math and this is amazing but true". The latest was from Larry Wake's presentation in which he said:

If we could implement a physical system with the storage capacity that matches the 128-bit address range of ZFS, that we would "literally evaporate all the oceans on earth".

This got me a little curious... Let's see:
ZFS = 128-bit = 3\*1026 [3E26] TB  (per filesystem)

Using 300GB spindles, you'd need about 1E27 spindles. Seagate's modern drives consume ~10W idle, and ~14W for both startup and in operation. So, lets go with 10W each, for round numbers. That's 1E28W or 8.8E31 KW-hr (over a full 24x7 year). That's 3.2E38 Joules.
http://www.seagate.com/cda/products/discsales/enterprise/tech/0,1084,362,00.html

If we apply E=mc\^2, we'd need to annhilate 3.5E21 kg of something (old beer cans?) to produce this much energy (power those spindles for a year).  The National Oceanic and Atmospheric Administration (NOAA) experts figure that the world's oceans consist of 275 million cubic miles. Seawater weighs 1027 kg/m\^3. That means all the oceans of the world weigh about 1.2E21 kg. Perfect conversion of the oceans to energy would spin those disks for about 4 months!!

Total World Consumption of Energy in 2002 was about 450 Quadrillion BTUs, or about 13E13 or 13 Trillion KW-hrs. Note (quadrillion means 1015 in the US, and 1024 in Europe... this stat is in the USA units).
http://www.eia.doe.gov/neic/infosheets/electricgeneration.htm

Therefore we'd need 6E18 times more capacity than the current worldwide consumption just to power this storage farm. If all the world's power generating capacity was a \*single\* grain of sand, then we'd need ALL the sand in ALL the beaches from around the entire planet to produce enough power for this storage farm. Est number of gains of beach sand: 7.5E18.
http://www.hawaii.edu/suremath/jsand.html

As far as the size of this storage farm (just laying the drives as close as possible to each other) when each drive is ~600K mm3 (the size of Seagate's 180GB disk). You'd need 6E32 mm3. The land surface of the earth is about 1.5E8 km2. You'd cover the earth's land surface to a depth of 2.5 million miles deep with disks to get this capacity (about 10x the distance to the moon!).
http://hypertextbook.com/facts/2001/DanielChen.shtml

Okay. The oceans are history! So are we. But ZFS will live forever. :-)

Let's look from another perspective. Lloyd tell us that the sub nuclear limit for storage is 1025 bits/kg. That means that a fully populated 128bit storage pool would have to weight at least 600 trillion pounds, for the the recording surface. Any less, and you can't exceed the 128bit space.  Sun employees see: http://zfs.eng/faq.shtml

A combat ready aircraft carrier weighs only 194 million pounds! The Empire State building weights only 1.1 billion pounds! A solid cube made up of 1 \*trillion\* pennies (273 feet//side) weighs ~5.5 billion lbs [about the length of a football field in each dimension]. That is 300% more pennies than the US mint has ever produced!

http://www.kokogiak.com/megapenny/thirteen.asp

A penny made after 1982 weighs just 2.5 grams (5.5116 E -3 lbs). That site suggests that 1 trillion (+ 16k or so to make a cube) pennies weigh 3.125 tons. But in 1982, the penny's composition was altered from 95% copper 5% zinc, to the current 97.5% zinc, 2.5% copper mix, which made it "cheaper" and lighter. That many pennies now weigh just 2.75 tons (US) or 2.5 tons (metric), so we need a few more cubes.

You'd need 110 thousand of those cubes to equal the mass of the theoretically perfect mass-efficient storage pool.

In reality, the latest Seagate 300GB disk weighs 1.6 lbs. You'd need 1E27 of these, or 1.6E27 lbs. The moon weighs 1.6E24 lbs. So you'd need the weight of 1000 moons!! And that's just in the spindles (sans racks, air handlers, etc). http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html

Hmmm. I'm thinking 128-bit filesystems might just be enough for a few years. :-)

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dcb

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