4 posts • joined 7 May 2010
In the IT world we tend to put untrained users on potentially hazzardous tools, then expect technology to make those tools "safe"... and then wonder why things go wrong.
Why does much of the world insist upon driver's training and testing before being allowed to drive a car on public roads? Because it helps. Does an educated driver eliminate all accidents? No, but it improves the situation.
CLEARLY, throwing technology alone at security is not working. We've been trying this for well over 20 years and the situation is getting WORSE, not better. Maybe it IS time to try education in addition to "improved" technology.
The usual response I get to this idea is, "education doesn't work!", my reply is, "it has never been seriously tried".
All the "education" attempts I have seen are based on chanting of rules, which attackers can then use as tools of their own, not true understanding of how the Internet actually works, and how it is used against us. Even the "advanced" security training starts from a premise of "you can't stop them", which I reject -- for the most part, we haven't seriously tried.
additional mass: bad.
Here's the problem: the additional heads and supporting mechanism adds mass to the seeking parts, which slows random seek times unacceptably. The goal is to reduce the mass of the randomly moving parts as much as you can.
questions/comments for round two...
Overall, I'm quite excited by the ideas of liquid immersion cooling, though I see a few issues:
Something about the two-phase cooling bothers me. Today, sure, breathing in the vapors of this fluid is harmless. What will we do next year if we find out the stuff is slightly toxic ("I gotta rebuild my entire infrastructure?"), or in a decade or two as I'm tugging around an oxygen bottle? I'd feel a lot more comfy with a low-tech, long-history substance... (my home's yard is contaminated by one of those miracle products of the past: PCBs..which, curiously were also a cooling fluid, so I'm a bit touchy about this!). I'm not sure I can be convinced that exposure to some new chemical, no matter how fascinating and useful its properties are, is harmless, but give it a shot, I'm listening.
One nice thing about old fashioned air cooling is I can stack machines floor to ceiling. Seems any form of immersion cooling will require vertical removal and insertion of parts "stacked" horizontally, which will probably limit the stacking to one or at the most two devices high, at least for applications which require that broken systems be replaced moderately soon and without impacting other systems. I suspect SOME of the potential density improvements would be negated by this. (on the other hand...the space required around a conventional rack (front and back) is pretty non-trivial, too.)
What about disks? I am sure many will say "SAN!" and leave it at that, but you still have an air cooling issue for the SAN, and much of the magic of liquid immersion is the almost complete elimination of active cooling equipment. I know you don't want to have the spinning platters in liquid, and I know traditional disks have vents to (at least) equalize their internal pressure...but could a conventional disk drive be practically made in such a way that it could be immersed along with its computer? I'm thinking either rigid enough case and seals to withstand the pressure of immersion and the reduced pressure of flying in a airplane cargo hold or a vent that could be sealed before immersion (don't screw up and forget to seal it!)
The big problem is the "ick" factor when you have to service something. Transformer oil would be particularly icky. Mineral oil (i.e., baby oil without the perfume) would be somewhat less annoying, but I still don't think I'd want to service a machine that was pulled from a vat of mineral oil dressed in office work attire.
I looked at a few discussions on liquid immersion cooling, one thing people keep missing is that almost ANY fluid is many, many times better at removing heat than air is. You don't need the optimal heat transfer characteristics, you want the optimal OTHER characteristics -- cheap, non-toxic, non-conductive, non-corrosive, likely to stay in its container, not harmful if it escapes its container, long-term stable in this environment, inert with regards to any of the materials used to fabricate the submerged parts, not likely to absorb anything that would change any of the above (i.e., distilled water is non-conductive, but that would likely change as dust and salts from human skin, etc. was dissolved into it over use..not to mention the residues on the products submerged into the water). The fact that it is a fluid almost guarantees superior heat transfer over free or forced air.
In this case, though, the phase change from liquid to gas absorbs a lot of extra heat from the product, and helps put an upper limit on the temp that any part will reach, which would not be true for fluid-only solutions.
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