... when the laser's mounted on a Frickin' shark's head.
... when the laser's mounted on a Frickin' shark's head.
So our democracy allows us to choose who to vote for (of course, you can always vote Donkeh!), but does not allow us to choose not to vote.
OCFS was originally designed specifically for storing Oracle datafiles, in a cluster, in a non-POSIX fashion. After that came OCFS2, which is POSIX compliant, but can deadlock when NFS exported due to the way NFS handles locking, in a way that can be worked around with the "nodirplus" NFS mount option (not available on all OSes, but Linux is ok). They since developed ASM (Automatic(ed?) Storage Management) which threw away the traditional filesystem presentation of your oracle datafiles, and subequently bundled that into the release of 11gR2 clusterware and extended the functionality to give us ACFS - ASM Clustered Filesystem.
11gR2 clusterware is designed to be clustered with shared storage, and depending on the options when created will happily give you a POSIX compliant clustered filesystem for any occasion - datafiles, regular files - whatever. It is Oracle's implementation of their "best practice" Stripe And Mirror Everything methodology with the aim of not only high availability, but consistently high performance, through spreading all your data across all your disks, and implementing mirroring in a sane way too (split your disks into two (or three!) failure groups, and the software will ensure there are 2 (or 3!) copies of each block. All you do is add disks to the pool(s), and if you have the space you can dynamically remove disks from the pool too. You can fsck, mkfs, mount and unmount it, take snapshots (!), and the lead-up to all that is all not much of a stretch from LVM. Google for Oracle ACFS and see the "Basic Steps to Manage Oracle ACFS Systems" section.
OCFS was only ever available for Linux, but ACFS now supports other platforms... probably doesn't matter to you. The one catch I've found so far is the ~1Gb RAM overhead to run the clusterware PER NODE. There's other reasonable stuff, like you need the network layer to be up in order to start the ACFS supporting services, so you can't put anything related to the basic boot process on those volumes.
The cost of 11gR2 clusterware?
As for the fencing method, it all works via heartbeat to disks in your ACFS pool. If the clusterware can't "ping" the disk within the threshold, it forces the system that's having the issue to reboot. Such is the nature of ensuring sanity when using shared disk. I suggest looking at it if your boxen can spare the RAM and you're happy to accept their OTN license agreement, as it really does seem to be one of Oracle's better products at an amazing price for what you get.
All fine, except if the system isn't for Oracle products then the vendor supporting the app will look at you funny when you tell them what enterprise OS you're running on.
RHEL has a certification relationship with many vendors. OVM, CentOS, and even to some degree Fedora, while being very similar as far as the administrator is concerned, are completely different when it comes to what level of supportability you'll get. At least 2 of those won't be particularly interested.
Of course, if you're supporting your own custom application then the answer is to run whatever OS you're comfortable with. If you want RedHat to look as a matter of priority at a technical problem you're having that is say related to their kernel, you'll have to pay them the license fee for that level of support. If your CIO wants a vendor to take some accountability, it has to cost something...
Then there are the certain applications that check the contents of your
Nobody really bothers with reporting good news (great news, yes, good news doesn't sell). Bad news of any kind loves to spin. If the radiation levels vary significantly over even the next week (this must include going down) then there are no dangerous radioactive materials involved - such things have significantly higher half lives than seconds, minutes, or hours... even days.
Despite the explosions, this "disaster" is still officially at least 1 level lower than TMI ever was, and that was more bark than bite. No meltdown. Some heavy-ish elements in the reactor may be somewhat dangerous to get close to for a while, and if they escape they will be of mild concern because they can't sustain a reaction like you get in a nuclear reactor, whether it be for power (Uranium/Plutonium and other scary stuff) or medicine (not so scary, but still troublesome to carry lumps in your pocket). The half-life of those materials within the reactor will be what determines the time it takes from the control rods being inserted to the reactor going cold (and yes there will be significant residual radiation inside the reactor in normal circumstances). Current temperatures within the reactor simply won't be high enough to vaporize much that could be a threat. It's just better for you not to inhale the stuff that is out there, just as it's better for you not to inhale cigarette smoke.
Secondly, think beyond the narrow-minded figure that "minutes" means no more than 10 minutes...
Say the half life of the radioactive gasses escaping the power station is 30 minutes. yes, 30. It's not unthinkable. In that case 400 millisieverts (reported to be an exposure at the reactor) becomes 25 millisieverts after 2 hours, or ~1.5 millisieverts after 4 hours, or somewhere in the region of reported levels in Tokyo after 5 hours or so. Is a 50km/h sea breeze enough for you in a tropical region? This means the radioactive material in the atmosphere is decaying fast enough not to pose a significant health issue. If there is enough exposure to worry about, people start taking iodine pills. Sure, iodine pills have even been distributed around the area, but how many have actually been taken so far? Possibly that one exposed worker, and whoever decided to panic. Yes, we're still quite peachy. Conventional fuel based explosions have happened at a nuclear power plant, because a byproduct of the residual reaction is an ideal, carbon-free, fuel (H2), and it ignited. When the reactor shutdowns, which have been hampered by the problems at the plant, complete, then the properly protected experts can have a look and the full story on how much dangerous nuclear matter has been released into the atmosphere will come out. I think you'll find it's negligible. The Japanese should be worrying about other things than the potential for a nuclear holocaust.
Generally the most dangerous nuclear material is that with a half life comparable to the lifespan of a human, ie decades. Yes there are spikes of radiation, but they dissipate quickly. 23 times the normal levels? I receive a day's worth of background radiation in an hour... as long as that doesn't happen for a month it's not likely to affect my health.
The real problem is if the nuclear fuel escapes into the atmosphere - that's where you end up with clouds that are dangerous. It hasn't happened in Japan yet, despite the physical assault the earth has thrown at it. Radioactive gases have been vented, and are short lived, and low risk because it's total exposure to radiation that causes the real health issues.
So far I still only see reports of one worker exposed to levels of radiation that are equivalent to a few years worth of radiation in an hour. That person may get cancer, and has every right to be worried, but you can get cancer from inhaling coal dust too. Or smoking, or, depending on what the media wants to pick up and run with, eating potatoes, or breathing. The point is, don't believe the hype that the media is using to sell stories. They don't seem to know what they're talking about. As soon as someone admits "radiation leak" the media broadcasts "Chernobyl" and the average Joe starts overreacting. These stories are alarmist, pure and simple, and it's selling newspapers and online advertising, while at the same time putting enough fear into people to affect the rescue and recovery efforts from the natural disaster.
I were in Tokyo I'd keep an eye out for any official reports about a genuine containment failure, while continuing to live my life.
Oh yes, those who use this as a tool to fear nuclear power need also to remember that this is a 40 year old plant, and there is new technology in such things which prevents the chance of even a partial meltdown, period. Very clever stuff where the fuel is embedded in material that expands as it gets too hot, which effectively moderates the fission reaction and prevents it going past a certain point.
Thousands were dead in minutes, and people seem to be insinuating that a fatality and some injuries after the natural disasters are beyond what might be considered statistically normal. Accidents happen, however unfortunate they may be.
The reason for the explosions is due to the knowledge that the hydrogen/oxygen gas mix released would be marginally radioactive with a half life measured in seconds, and the intent was to contain the gas for long enough for it to be rendered inert. The risk of explosion was acknowledged, people were warned, and when when it did blow, well they had had opportunity to move people further away than they were. The escaping gases ARE raising radiation levels
It takes a few days for a reactor that has had the control rods slammed into the shutdown position to cool down, and in the meantime the generator still generates some heat and needs some cooling. When the backups and backups of backups failed, they chose the less desirable route, in pumping in sea water. As it ain't pure water, you end up with slightly more radioactive matter with a half-life which is more like minutes than seconds, so less desirable, somewhat radioactive gas results, which is harmless well before it travels that 30km. There will be no noteworthy radioactive residue when the cool down is complete, except for what's in the reactor itself.
The reactor everyone's jumping up and down about has survived an earthquake and tsunami well beyond design spec, and as for the inconvenience of lost power. Yes, they lost backup and backup backup diesel generators, but they also had battery backups which held until mobile generators could be moved in. I also dare anyone to tell me what power generation scheme in that location at that time would not have failed, so of course there will be power rationing and/or blackouts.
The Japanese got the sum of their design and processes of their nuclear reactors right, and they are taking every precaution they can to ensure public safety. The biggest mistake was trying to contain the gas from the reactor instead of venting to the atmosphere, because the media are making it look like these gas explosions might be a sign that a meltdown is imminent. It isn't, but the media never let facts get in the way of a good story. Those responsible for the reactors are simply Doing The Right Thing [TM].
Outside of a dog, a book is man's best friend. Inside of a dog, it is too dark to read.