Friday, July 11, 2008


The server version of Mac OSX 10.6, codenamed Snow Leopard and due out "in about a year", includes support for ZFS, a filesystem developed in the last few years by Sun that they have included in their Solaris operating system and made open source. ZFS was intentionally designed to have theoretical limits that far outstrip what we can actually do with hardware, meaning, essentially, that we will never run out of room. ZFS uses 128 bit addressing, which in layman's terms means the amount of data you can store in a single ZFS is friggin' huge. How huge? Well, apparently boil the oceans huge. This quote from Jeff Bonwick, the team lead for the ZFS project, sums it up thusly:
"Although we'd all like Moore's Law to continue forever, quantum mechanics imposes some fundamental limits on the computation rate and information capacity of any physical device. In particular, it has been shown that 1 kilogram of matter confined to 1 litre of space can perform at most 1051 operations per second on at most 1031 bits of information.[10] A fully populated 128-bit storage pool would contain 2128 blocks = 2137 bytes = 2140 bits; therefore the minimum mass required to hold the bits would be (2140 bits) / (1031 bits/kg) = 136 billion kg. To operate at the 1031 bits/kg limit, however, the entire mass of the computer must be in the form of pure energy. By E=mc², the rest energy of 136 billion kg is 1.2x1028 J. The mass of the oceans is about 1.4x1021 kg. It takes about 4,000 J to raise the temperature of 1 kg of water by 1 degree Celsius, and thus about 400,000 J to heat 1 kg of water from freezing to boiling. The latent heat of vaporization adds another 2 million J/kg. Thus the energy required to boil the oceans is about 2.4x106 J/kg * 1.4x1021 kg = 3.4x1027 J. Thus, fully populating a 128-bit storage pool would, literally, require more energy than boiling the oceans."