Have you considered space maps for tracking free space? I thought that was one of the more interesting ideas in ZFS.

Anyway, great work on the SMP scalability. It is refreshing to see a concerted effort in reworking the system to be more SMP friendly, rather than the profuse and convoluted locking that most others have adopted.

Fused glass display is fine. It is the soldered in RAM, proprietary SSD, and glued in battery that are totally unacceptable. Ordinarily, I'd double the RAM in a year for a pittance, but now Apple forces you to pay a hefty premium for a limited amount of RAM up front, obsoleting the machine that much sooner. Replacement SSDs are available eventually, but with few options at high cost. Finally, who wants to take/send in their machine for battery service every two years? Batteries are consumables, and shouldn't be glued in anymore than a toner cartridge.

While the NIST curves are suspect, slow, and problematic in a number of other ways, there are fast and safe elliptic curves.

I'm sorry you took it that way, I was rather hoping that you would read it and develop an appreciation of how fluid fueled reactors are utterly different and fundamentally superior. Then, hopefully discontinue suggesting that people "educate" themselves with the typical anti-nuclear/thorium propaganda. While your links do not have tailored rebuttals yet, I expect that all of the various specious arguments are addressed within, repeatedly.

For an actual education, I would suggest starting at Energy from Thorium, or the forum if you have technical questions.

For an author of typically insightful comments, you would do us all well to educate yourself rather than citing nonsense and propagating FUD. Molten salt reactors are a silver bullet capable of end our dependance on fossil fuels. Working to tarnish the singular available option with that potential is not helpful.

Molten salt reactors are by definition meltdown proof, as the working state is already molten. The fuel salts are impervious to radiation damage, and the vessel will melt long before the salts boil, at which point the salts will drain onto the floor and ultimately still end up in the drain tank. The fuel is the coolant, and it has excellent thermal conductivity. At those temperatures heat dissipates rapidly, minimizing the difficulty of passive cooling. Even if the plant were turned into rubble, the heat would still dissipate into the surrounding environment and the salt would eventually freeze, all the while trapping the dissolved fuel and fission products. The freeze plug is a convenience to minimize damage to the reactor, but is not necessary for avoiding a large scale release of radiation--that is virtually impossible by any means. In the absurdly improbable event that some of the salt did boil away, that process itself would rapidly cool the bulk of the remaining salt, minimizing the release into the environment.

Unlike molten salts, the ceramic fuel elements of solid fueled reactors have very poor thermal conductivity and much higher melting temperatures. Worse yet, the rods contain more than a years worth of fuel, and trap all of the fission products over that period in a thermal insulator, with the volatiles inevitably released when cooling fails and the ceramic melts. That is a meltdown, and the escape of years worth of volatile fission products is indeed a very serious problem which simply doesn't happen with salts.

A thorium fueled molten salt reactor is continuously replenished, and contains no excess fuel. The magic of thorium is that it breeds in a thermal spectrum, and offers a simple chemical mechanism for reprocessing, not available in other fuel cycles. The thermal spectrum also requires much less fuel than the fast spectrum. Thanks to the fluid fuel, some volatile fission products like Xenon simply bubble out, and are continuously removed and sequestered. Others form stable salts with fluorine. All together, there is a minimum amount of fissile and decay heat present in any accident scenario, and the most dangerous long term hazards like cesium and strontium remain dissolved. The fluorine salts are among the most chemically stable compounds, and do not react violently with air or water. They are by far the safest place for nuclear fuel and fission products, where they can fissioned thoroughly, leaving virtually no waste.

With molten salt reactors, one has to be extremely creative to imagine disastrous accident scenarios. As a bonus, molten salt reactors were extensively researched, and about 10 years away in the 1970s. It might take a little longer today, but with a concerted effort, we could be mass producing reactors within 20 years, and well on our way to replacing all fossil fuel consumption later thus century. It is the one and only proven technology capable of that, so we ought to pick up where we left off without delay.

Is NFTables suitable as a generic packet classifier, or is it strictly limited to packet filtering? Van Jacobson's net channels offer the possibility of extraordinary improvements in efficiency and performance, great simplification of drivers, ease of development, and much improved flexibility. The one missing piece is a flexible packet classifier. While NFTables looks like it incorporates many of the essential ideas, it isn't clear wether it is built with this in mind. If not, I'd like to see this fixed before it is integrated.

I've long thought that that we should replace the whole mess of statically #ifdef'd protocol switch statements and filtering mechanisms tacked on as an afterthought. That instead, we should build all of that upon something like BPF at the very lowest level, and have it dynamically compiled to native code. Protocol classification and filtering rules would be translated to BPF like code fragments to be assembled by the system, and it would be high performance and truly modular. Periodically analyzing the statistics of actual protocol and traffic flows, the system could also recombine the fragments in the most efficient way possible.

The digital revolution is largely irrelevant--it is dwindling wealth which will kill jobs and inflame social unrest. As long as the pie is shrinking, and the fools making policy treat our economy as a zero sum game, there will be no end of problems. Certainly the distribution of wealth must be addressed, but it is also absolutely essential that we grow the pie.

Jobs and natural resources are necessary inputs to wealth creation, though by no means sufficient. Limiting the scope of the discussion to jobs is a futile exercise and misses the key point: our collective prosperity rests entirely on energy. Both jobs and natural resources are directly dependent on access to affordable and abundant energy. While automation will continue to reduce the need for human input, energy is not optional. It is critical that we secure a reliable and economical source of energy now, or the suffering will be inevitable as fossil fuels become ever scarcer.

Without access to energy, we won't even be able to feed ourselves, much less maintain our existing infrastructure, and civilization will decay and crumble. There is no shortage of work to be done, but we are increasingly constrained by our resource inputs. If only people could develop an appreciation for just how instrumental cheap fossil fuels have been in supporting our present quality of life, the sooner we could seriously work toward replacing them. Unfortunately, that requires embracing nuclear energy, as it is the only viable replacement we have for fossil fuels. Needless to say, I'm not very hopeful about our future.

Unified theories are more attractive, but every new way of looking at physics (that accurately models reality) is one more potential avenue of insight into the fundamental nature of our universe. This is definitely an exciting discovery, though I do not share their enthusiasm for boiling all of reality down to particle interactions with geometry, rather than statistics.

The Copenhagen interpretation of QM is a disgrace, and any self-respecting scientist should be ashamed to support a theory that hides reality behind a veil of statistics, and uses that as an excuse to cease the pursuit of truth. As useful as QM is for calculations, mainstream physics has been stuck in a rut ever since, with the persisting complacent acceptance of enshrined theory. The same applies to nonsense like BCS theory, even though it isn't nearly as useful as QM.

There is no solid basis for the existence of particles in the first place, much less that the universe is fundamentally statistical in nature. Hopefully, simplifying our understanding of "particle" interactions will help illuminate a world without particles and rubbish like wave-particle duality. It seems a far more rational conclusion that that the wave and quantum nature observed emerge from a reality with a fundamental wave nature, rather than the spectacular contortions necessary with particles.

Wandering a but further off topic, Dr. Johan Prins also developed a very compelling and useful model of superconductivity, which is based on a wave nature of electrons. It dispenses with non-locality, and replaces it with unified waves. Boson "particles" no longer merely share the same energy state, they may merge into a unified wave, or split into quantum--as defined by boundary conditions. (shared electrons in orbitals, photons in lasers, BEC condensates, neutron stars, etc. would follow the same logic; waves constrained by boundary conditions.) It is both predictive and supported by evidence, yet sadly, no one has attempted to verify the results or even consider the theory as far as I know. Apparently, you must not stray too from the accepted dogma, even while other evidence mounts and the prevailing theory continues to fail. More epicycles and such...

There are no satisfactory workarounds, and never will be. The crypto needs to be handled within ZFS or it becomes an over complicated and inefficient mess. (As you are probably aware.) Consider a ZFS mirror on top of two disks encrypted by the OS; even though the data is identical, it now needs to be encrypted twice on write, and decrypted twice on scrub. For ditto blocks, multiply the amount of crypto work by another two or three. There are now (at least) two keys to manage and still no fine granularity access. Adding more vdevs to the pool only exacerbates the problem.

Copy on write transaction oriented filesystems like like ZFS are the natural place for crypto, as constructing a nonce is trivial; simply append the transaction ID, block offset, etc. It couples perfectly with stream ciphers like Salsa20 (or XSalsa20 for the extended 24-byte nonce), and offers the possibility of extremely fast, flexible, and efficient crypto. There is no expensive key setup required and no need to generate ESSIVs. No need to use expensive crypto modes on top of conventional block ciphers, which require multiple encryptions or other expensive operations like GCM. Furthermore, Salsa20/ChaCha is not only highly secure and trustworthy, but extremely fast, simple, and elegant.

After all of the work of hammering a square peg into a round hole with conventional full disk encryption, performance of Salsa20 in ZFS/HAMMER/btrfs would rival hardware accelerated block device crypto and be useful on a far greater array of hardware. (Typically it should even surpass it, as redundant crypto operations are eliminated.)

There is ongoing work on ZFS crypto at https://github.com/zfsrogue/zfs-crypto, though I'm not sure how it is progressing. Having zfs-crypto integrated would be very useful, not only for efficiency reasons, but for the simple and flexible key management. While there are alternatives to a number of other features that ZFS offers, none of them come close to offering the flexibility and convenience of ZFS.

It is worth mentioning that this issue is exclusive to solid fuel reactors. With fluid fuel, the problematic gasses just bubble out, and require no special attention. There are no safety issues with rapidly cycling a LFTR or other molten salt reactor. In practice, they will only be limited by how fast the turbine can spin up and down, and the reaction will follow suit.

I think you are somewhat unfairly overlooking kerberos authenticated NFS, and that is the only sensible way to use it. Better yet, with encryption and integrity protection as well.

Yes, selling something you can't provide is asking for trouble. If many people are saturating gigabit links 24/7, the pricing needs to allow for that. However, transfer caps and violations of net neutrality are not the answer.

The best solution is to advertise honestly, and the FCC should enforce this. Connections should be sold by minimum guaranteed rate, and maximum burst rate, with all else neutral. If there is any prioritization, it should only be among a customers own packets, at their request. This is easily done with guaranteed bandwidth available, and without any violation of network neutrality or impact on other users.

Selling by guaranteed rate has the advantage that there is a hard relationship between what is offered and what is purchased. If customers purchase more, the ISP must build more--rather than arbitrarily oversubscribing their networks. This incentive to invest in infrastructure is completely missing today. Since most people won't be using 100% of their allotted bandwidth, the excess can be divided fairly.

This would work great for google, offering something like 50Mb/s guaranteed and 1Gb/s burst. The minimum guaranteed bandwidth that cable and phone companies can provide would certainly look pitiful by comparison, but would be an honest reflection of what they can actually provide, rather than the meaningless "up to" numbers.

Unfortunately, it seems that JVM based languages are still limited by the lack of unsigned types. What a remarkably stupid decision to omit them.

Contrary to what you might think, carbon is actually safer at those temperatures. Under neutron bombardment at low temperatures, the Wigner energy can build up, and that is the source of the problems. However, at the operating temperatures of molten salt reactors, solid graphite is quite safe. (You can purchase graphite crucibles good to 2500C.) There is further discussion here.

The ultimate goal of our endeavors should be to produce wealth for human beings, not mindless jobs, nor backbreaking labor. If tedious and burdensome tasks like agriculture, manufacturing, and mining can be done by machines, all the better. That should free up people to do other things, including not slaving away for 40-60 hours a week. Increases in productivity are always a good thing--the problem is in the distribution of wealth, or rather the utter lack thereof nowadays. As jobs inevitably evaporate, we need to find new and better ways of doing this.

One particular area of productivity deserves special mention. Virtually all of wealth is derived from energy, yet energy has no intrinsic value. It is purely an input, so energy generation should be done as cheaply and efficiently as possible, as it compounds the cost of everything else. It is asinine to make it into a jobs program, yet that is exactly what Obama has done with his recent proposal.