If you want to do it with a script or with the CLI, remember that the disk cannot be mounted or otherwise be in use. If you have a few disks to wipe, it will save time in the long run if you use a script like the one shown below. This script wipes the first and last 4096 kilobytes of data from a drive ensuring that any partitioning or MetaData is gone and you can then reuse your drive. Warning, all other data on the drive will become inaccessible!:

#!/bin/sh
echo "What disk do you want"
echo "to wipe? For example - ada1 :"
read disk
echo "OK, in 10 seconds I will destroy all data on $disk!"
echo "Press CTRL+C to abort!"
sleep 10
diskinfo ${disk} | while read disk sectorsize size sectors other
do
        # Delete MBR, GPT Primary, ZFS(L0L1)/other partition table.
        /bin/dd if=/dev/zero of=/dev/${disk} bs=${sectorsize} count=8192
        # Delete GEOM metadata, GPT Secondary(L2L3).
        /bin/dd if=/dev/zero of=/dev/${disk} bs=${sectorsize} oseek=`expr $sectors - 8192` count=8192
done

How to safely remove rest of GPT?
Disk have actual data (part of ZFS), I am don't need to destroy this
data.

GEOM: da6: the primary GPT table is corrupt or invalid.
GEOM: da6: using the secondary instead -- recovery strongly advised. //

You need to zero out the backup gpt header. Geom locates that header
using (mediasize / sectorsize) - 1. I think mediasize/sectorsize is
exactly what's displayed by diskinfo -v as "mediasize in sectors", so
that number - 1 would be lastsector in:
dd if=/dev/zero of=/dev/da6 bs=<sectorsize> oseek=<lastsector> count=1
//

In case when you have not valid primary header, gpart destroy will not
touch first two sectors. In you case you can wipe only last sector, like
Ian suggested, but use gpart destroy -F da6 instead of dd. //

You need to use gpart destroy -F to CORRUPTED GPT, this command will wipe last sector where GPT backup header is located. Since GPT is in CORRUPT state, the primary header
will not be overwrited by this command.

When both primary and backup headers and tables are valid, gpart destroy overwites PMBR, primary and backup headers.

Mireille Goyer
September 25, 2021 at 1:40 pm
The “growth” of the student pilot population in the last 10 years is driven only by a change of FAA recording as stated in Note 1.

Note 1: In July 2010, the FAA issued a rule that increased the duration of validity for student pilot certificates for pilots under the age of 40 from 36 to 60 months. This resulted in the increase in active student pilots to 119,119 from 72,280 at the end of 2009. Starting with April 2016, there is no expiration date on the new student pilot certificates, which generates a cumulative increase in the numbers.

The student “growth” you mentioned is in fact the student dropout rate. It is increasing (especially among female student pilots). Meanwhile, the level of annual student starts (table 22) is decreasing – from 66,953 in 2006 to 55,298 in 2011 to 49,933 in 2020.

Pilot candidates who go through the trouble of getting a medical certificate (the only students recorded by the FAA) know about the cost of learning to fly. That is not the deterrent. As an flight instructor, I have found that the deterrent is two folds: unexpected complexity (flight environment + new avionics) and uncontrollable training timeline. This does need to be addressed if we are to grow the Private aviation sector.

Larry S
September 26, 2021 at 6:41 am
I’m not buying into this hypothesis.

Light Sport was gonna revolutionize aviation, simplify training and bring the acquisition cost down to reality (sub $100K) … where did that take us? The move to instrument panels filled with flat screen avionics was going to simplify manufacturing ergo reduce costs and lure millenials to them … where did that go? The move to limited ASTM standards was going to simplify things; what meaningful success did that have and where is MOSAIC? Cirrus was going to be the answer yet all they did was become the airplane du jour for the very well heeled. Mooney’s were gonna wow prospects with efficiency of speed and where did that get them? So now someone wants me to believe that SVO airplanes flown with an iPhone are going to do it. It’s just another bump in the road for GA unless and until mere every day mortals can afford to buy a decent entry level airplane that isn’t 50+ years old. The success of E-AB airplanes — built in numbers greater than certificated airplanes proves it. In the end, it’s all about acquisition costs. Sure, there are a bevy of other irritants and obstacles in the equation but the MAJOR factor is cost.

A SVO airplane isn’t going to make them any cheaper. The trial lawyers and the intransigent FAA will see to that. Your own statement, “Oh, the wealth is growing, all right, but the industry’s efforts to divert it into new airplane sales have yielded survival, but not meaningful growth” hits the problem on the head but evades the root problem … acquisition cost. When is the last time anyone here knew any individual who went out and bought a new airplane? Flight school puppy mills are buying some but not individuals. Bring the cost of a new Cessna 172 down near the cost of an E-AB RV-7 and ‘they’ will come. Until then, all everyone is doing is throwing golf balls against a wall hoping that one of them will stick. The VFR Piper 100 comes close but they are still a bit high and — as I understand it — aren’t available to individuals in meaningful numbers.

Let’s just see what happens when Van’s reveals his RV-15. I’m betting they’ll have to hire still more employees to fill the clamor for them.

I have a friend who is buying and selling used clean Cessna 182’s like hotcakes for between $100K – $150K, sometimes less. THERE is your problem. Pilots and pilot wannabe’s ARE there, they want airplanes but just can’t afford it so they take their discretionary dollars elsewhere or buy nice used airplanes. Every time I tell someone I own a M model Skyhawk, they ask if I want to sell it. THERE’s your problem.

Simplified Vehicle Operation. I recently spent an afternoon with a friend who’s in management for a major airframer and almost at the same instant, we got around to asking each other about this idea. It hasn’t gotten a lot of coverage but deserves to because it represents the inevitable advance of cockpit automation that will require less traditional knowledge of flying—call that stick and rudder if you like—and more systems management and simplified operation and decision making.

This shouldn’t sound new. Pilots of technically advanced aircraft have been doing exactly this increasingly with each new generation of avionics. To the extent that this tilt toward automation has evolved training, it really hasn’t. The ACS adds the requirement to demonstrate knowledge of and competence with these systems, but fundamental training remains largely unchanged.

If SVO gains traction—and it inevitably will even if it’s not called that—what evolves into the ACS of the future won’t look like what we have now, unless we somehow manage to sabotage it. //

Yeah, it’s robotic flying. Traditionalists will howl, but traditionalists have run out of ideas to grow pilots and build more airplanes for them to fly. Eventually, there could be a specific rating for SVO, says GAMA’s Lowell Foster. “If you get an SVO license, there’s no expectation that you have to be proficient to fly a regular airplane,” he said at the NBAA event. Given the reactionary hidebounded nature of GA, it’s impossible to say how long such an evolution might require. It will take younger executives to drive it, I suspect. //

what got me thinking about this, in addition to the conversation with my friend, is a comment someone made on the video I did about hand propping. He mentioned that he had flown Cubs where I did, too, at College Park, Maryland. He said he never could make friends with the J-3; just couldn’t figure it out. And he thought that was bad for aviation. I concede the point. Old airplanes, and especially the J-3, force you to conform to their oddities and inadequacies and around this we sometimes erect the artifice that this makes them good training airplanes. They have character and personality.

Maybe. But probably not. If I were doing a Young Eagle flight to introduce a kid to the wonder of lift and had the choice of a modern LSA with a little glass in the panel or a Cub, I’d take the former. It has more to do with the future said kid is likely to encounter than a crotchety ragwing designed when Franklin Roosevelt was president.

Commercial KVM over IP solutions are usually expensive, and one of the reasons PiKVM v3 has been so popular so far is its comparatively low price of just $145 including a steel case. Shipping adds $20 to the US, and $30 to the rest of the world, and backers will not have to wait for too long, as shipping is expected to start in October, a few weeks after the Kickstarter campaign ends. More details may also be found on the official website.

https://pikvm.org/

The way in which an aircraft is loaded is critical to the safety of the flight. Too heavy at the rear and it could tip onto its tail. Too heavy at the front and the pilots will struggle to get the aircraft airborne. As a result, cargo and baggage are loaded in a way in which they will balance out how passengers are sat in the cabin.

The load sheet provides the pilots with information as to how the aircraft has been loaded. From this, we are able to set the trim of the horizontal stabilizer to ensure that all takeoffs handle in the same way.

Asimov did not have a bar mitzvah, which he attributed to his parents choosing to raise him without religion and not, as some suspected, “as an act of rebellion against Orthodox parents.” However, he said, he “gained an interest” in the Bible as he got older, although he eventually realized that he preferred the type of fictional books that would one day make him famous: “Science fiction and science books had taught me their version of the universe and I was not ready to accept the Creation tale of Genesis or the various miracles described throughout the book.”

Having the first name “Isaac,” in the 21st century, isn’t necessarily a certain giveaway that a person is Jewish. But in Asimov’s time, it almost always was. And while Asimov sometimes faced pressure to change his name for professional reasons, he always stuck with his given name.

“I would not allow any story of mine to appear except under the name of Isaac Asimov,” he wrote. “I think I helped break down the convention of imposing salt-free, low-fat names on writers. In particular, I made it a little more possible for writers to be openly Jewish in the world of popular fiction.” //

As for Israel and Zionism, Asimov was something of a skeptic. In his final book “Asimov Laughs Again,” published around the time of his death, Asimov stated that he had never visited Israel and didn’t plan to, although he attributed that in part to his habit of not doing much traveling.

“I remember how it was in 1948 when Israel was being established and all my Jewish friends were ecstatic. I was not,” he wrote. “I said: What are we doing? We are establishing ourselves in a ghetto, in a small corner of a vast Muslim sea. The Muslims will never forget nor forgive, and Israel, as long as it exists, will be embattled. I was laughed at, but I was right.”

One of the most spectacular Einstein rings ever seen in space is enabling us to see what's happening in a galaxy almost at the dawn of time.
The smears of light called the Molten Ring, stretched out and warped by gravitational fields, are magnifications and duplications of a galaxy whose light has traveled a whopping 9.4 billion light-years. This magnification has given us a rare insight into the stellar 'baby boom' when the Universe was still in its infancy. //

The Molten Ring (formally named GAL-CLUS-022058s) is just such an Einstein ring, magnified by the gravitational field around a huge cluster of galaxies in the constellation of Fornax. So powerful is this effect that not only does the distant galaxy appear in four distorted images, it's magnified by a factor of 20.
When combined with the Hubble Space Telescope, the resulting images are as detailed and sharp as observations taken with a telescope with a huge 48-meter aperture. From this, a team of researchers led by Anastasio Díaz-Sánchez of the Universidad Politécnica de Cartagena in Spain worked out that light from the galaxy has traveled 9.4 billion light-years.

We’re committed to protecting the environment. That’s why we provide convenient trade in and recycling solutions that help us reuse precious materials to make new Dell products. Get started now. It's easy.

Within modern software development practices, you are expected to build software from a two- or three-sentence business feature. The name of the game is to not go too deep and to constantly iterate. This is far different from the traditional waterfall method, where you would spend six months figuring out the requirements analysis before you wrote a single line of code. With a waterfall approach, this is fine because you will know the end state in order to create your database objects. However, you simply can’t do this if you’re following agile methods because there is no way to build a data model from a three-sentence business requirement, and you’re constantly having to rework your database. //

RDBMS Growth at Travelers
YEAR Tables in production
2013 40
2015 70
2017 100
//

We taught every team how to data model in JSON, as opposed to the rigid tables and rows of a relational database. This was an eye-opening experience for many people, who now understood how this affected the speed at which our teams could deliver software into production. //

At the end of the day, if you’re doing it right in relational, you have a lot of tables, and if you’re modeling your data properly, you will have a lot of objects even for the simplest use cases. Once we determined that our database was slowing us down, we knew it was time for a change.

After decades of trying, the B-52 will finally get new engines, with Rolls Royce being tapped for the contract that could be worth up to $2.6B. //

The F130 beat out General Electric's CF34-10 and Pratt and Whitney's PW800 to secure this deal. Pratt and Whitney was effectively the incumbent in this competition, though the TF33 engine that powers the B-52H now has been out of production since 1985. The company has continued to provide support for TF33s found on B-52Hs and other Air Force aircraft since then, but at an ever-growing cost. As of 2016, the Air Force was spending approximately $2 million per engine to overhaul TF33s every 6,000 flight hours. //

The TF33, which has powered the B-52H since the very first of these bombers entered service in the 1960s, is also just a dated, inefficient, low-bypass design. “Once installed, the F130 will provide vastly greater fuel efficiency while increasing range and reducing tanker aircraft requirements,” Rolls-Royce's website notes. This was another major factor for the Air Force in deciding whether or not to proceed with the re-engining effort. //

The TF33, which has powered the B-52H since the very first of these bombers entered service in the 1960s, is also just a dated, inefficient, low-bypass design. “Once installed, the F130 will provide vastly greater fuel efficiency while increasing range and reducing tanker aircraft requirements,” Rolls-Royce's website notes. This was another major factor for the Air Force in deciding whether or not to proceed with the re-engining effort.

When it comes to cost, the F130 also has the benefit of being an established in-production design. F130 is the military designation for Rolls-Royce's popular BR700, thousands of examples of which power a variety of different business jets, as well as the Boeing 717 airliner. U.S. military C-37A and B aircraft — designations applied to Gulfstream V and 550s, respectively — as well as the Air Force's Bombardier BD-700-based E-11A Battlefield Airborne Communications Node (BACN) aircraft, already use versions of this engine, further simplifying maintenance and logistics chains.

Fairness and integrity in our elections is the fundamental bedrock of our republic. If both of these principles are missing, we will gradually lose our two hundred years-plus experiment with self government. What we will have instead, at best, is a banana republic where the results of an election will always be in dispute, and that is a recipe for anarchy.

CDC
@CDCgov
New @CDCMMWR shows counties w/ school mask requirements had a smaller increase in pediatric #COVID19 case rates than counties w/o school mask requirements. #MaskUp in schools to help control the spread of COVID-19 in children and adolescents. http://bit.ly/MMWR92421c
2:55 PM · Sep 24, 2021 //

Notice the massaging being done to the language in this announcement. It doesn’t actually say schools with mask mandates show a smaller increase in pediatric COVID-19 case rates. Rather, it says “counties,” and we’ll get to why that is in a minute. Further, the CDC absconds from including in their graphic the actual, numerical difference being touted.

For posterity, here’s the link to the full study so you can see exactly what it actually covers.

https://www.cdc.gov/mmwr/volumes/70/wr/mm7039e3.htm?s_cid=mm7039e3_w

In short, what we have is a “study” that didn’t even cover a period where children were in school — save for a week or so. The “study” is also based on a data set of counties that do not control for prior infection rates, testing capacity, etc. in order to conduct a valid comparison between areas that have school mask mandates and ones that don’t. And even still, they came up with a result that shows almost no difference in the real number of cases.

Lastly, just to put a fine point on all this, the CDC’s own study admits that it’s ecological and should not be used to assign causation in regards to masks and infection rates. They also admit a lack of control regarding several other key variables.

Let me start by dispelling the notion that I think smaller, modular, manufactured nuclear power systems – often called SMRs or micro reactors – are the be all and end all solution to anything, including climate change or energy security.

Though not THE solution, they have the potential to be a crucial, uniquely capable part of a fully-integrated, 0% emission climate-solving grid.

The best of the breed build on lessons from aircraft manufacturing, submarine construction, electric vehicles, wind & solar and even computers. They are leavened with six decades worth of experience in building, operating and maintaining extra large nuclear systems. They address some of the public relations challenges that have plagued very large reactors. //

As former submarine engineer officer who also had the rare opportunity to plan and budget for fleet level nuclear power training, maintenance and construction programs, I have a personal understanding of how economies of series production and standardization work to help keep costs under control and schedules predictable.

It is enlightening to see how much costs fall when you can train a group of operators in a common speciality and send them out to several dozen plants that have identical equipment, spare parts lockers and layouts. It’s also easy to see how maintenance procedures can be written once and used by all and how alterations can be planned, reviewed and implemented. These are just a few of the examples I can list. Rules protecting confidential information prevent me from sharing quantified details. Space prevents me from listing other examples.

It shouldn’t surprise anyone who has made anything that people learn to do things with experience or that doing the same thing repeatedly produces better results the more often the task is done. Those learning curve-related improvements don’t require mass production of thousands or millions of units, they start improving cost and performance with the second unit. //

The modern renewable industry – wind and solar energy collection systems – demonstrate the utility of replication. Starting from the high cost systems of the early 2000s, the industry took advantage of tax credit and mandates originally designed to help them build markets and achieve scale economies. Their impressive cost reduction performance is more attributable to the economy of learning by doing than it is to technological innovations and new inventions.

Olivier Cochard-Labbé, the original founder of FreeNAS, shares with us a presentation outlining the history and beginnings of what would become the world's most popular storage operating system.

Slideshow explaining VDev, zpool, ZIL and L2ARC and other newbie mistakes!

I've put together a Powerpoint presentation(and PDF) that gives some useful info for newbies to FreeNAS. I decided to create this slideshow because in the last 5 months I've been on this forum I've seen a lot of people confused about vdevs, zpools, zils, l2arcs, etc. Hopefully we can put to rest alot of the confusion once and for all.

We get a large amount of duplicate threads with the same questions being asked every other day. Personally, we get them so often I decided to stop answering them and decided a better use of my time would be to create this presentation. I literally read every thread and every post that goes on the forum. So if I don't answer either the answer is in the thread or the answer is found in this presentation or FreeNAS manual. Answering every 3rd thread with "Consult the manual" gets a little old after a while and I have better uses for my time.

This presentation also contains a lot of information that is explained in a little more detail for new users. It includes many common errors newbies make and can save you some heartache. If you are brand new to FreeBSD, I recommend reading the manual cover to cover. There are a lot of recommendations throughout the manual, and they are typically there because they are an error trap for many people.

I've saved this in Powerpoint because I have some animations in the slideshow. I'm not sure what other formats would work. If you would like this in another format that supports animations please let me know and I'll see what I can do. Currently I provide this in a powerpoint presentation and PDF. The PDF has no animations therefore the Powerpoint is preferred.

Yet RAID is not only about availability. Its other advantages are important and, for most, possibly more important.

• Performance. Striping data across multiple drives can dramatically increase bandwidth for large file apps like video editing.
• Capacity. Putting 4-12 drives in a RAID gives a large virtual disk that is much larger than any single drive.
• Management. After the often painful setup process - and until something breaks - RAID arrays are simpler to manage than individual disks. //

Many are still using small RAID5 arrays with 10^-14 error rates - me too! - and RAID5 seems to work fine. But adjustments should be made to account for the unchanged error rates.

• Always maintain a minimum of 2 copies any data stored on a RAID - 1 on the RAID and 1 elsewhere.
• Where there is a drive failure pull any unbacked up data - latest documents that aren't backed up - off the RAID before replacing the failed drive.

Since RAID arrays are more complex than individual drives, they are more likely to fail. But until they do they are more convenient, faster and larger than any single drive.

RAID 5 protects against a single disk failure. You can recover all your data if a single disk breaks. The problem: once a disk breaks, there is another increasingly common failure lurking. And in 2009 it is highly certain it will find you.

Disks fail While disks are incredibly reliable devices, they do fail. Our best data - from CMU and Google - finds that over 3% of drives fail each year in the first three years of drive life, and then failure rates start rising fast.

With 7 brand new disks, you have ~20% chance of seeing a disk failure each year. Factor in the rising failure rate with age and over 4 years you are almost certain to see a disk failure during the life of those disks.

But you're protected by RAID 5, right? Not in 2009.

Reads fail SATA drives are commonly specified with an unrecoverable read error rate (URE) of 10^14. Which means that once every 100,000,000,000,000 bits, the disk will very politely tell you that, so sorry, but I really, truly can't read that sector back to you.

One hundred trillion bits is about 12 terabytes. Sound like a lot? Not in 2009. //

So now what? The obvious answer, and the one that storage marketers have begun trumpeting, is RAID 6, which protects your data against 2 failures. Which is all well and good, until you consider this: as drives increase in size, any drive failure will always be accompanied by a read error. So RAID 6 will give you no more protection than RAID 5 does now, but you'll pay more anyway for extra disk capacity and slower write performance.

Gee, paying more for less! I can hardly wait! //

Originally the developers of RAID suggested RAID 6 as a means of protecting against 2 disk failures. As we now know, a single disk failure means a second disk failure is much more likely - see the CMU pdf Disk Failures in the Real World: What Does an MTTF of 1,000,000 Hours Mean to You? for details - or check out my synopsis in Everything You Know About Disks Is Wrong. RAID 5 protection is a little dodgy today due to this effect and RAID 6 - in a few years - won't be able to help.

Finally, I recalculated the AFR for 7 drives using the 3.1% AFR from the CMU paper, using the formula suggested by a couple of readers - 1-96.9 ^# of disks - and got 19.8%. So I changed the ~23% number to ~20%.

Comments welcome, of course. I revisited this piece in 2013 in Has RAID5 stopped working? Now that we have 6TB drives - some with the same 10^14 URE - the problem is worse than ever.

The answer to the problem of blue staters escaping to red states actually requires some effort on your part. Screaming on social media is easy, real action is hard.

You’re going to have to run for local office.

I know, the thought just made you cringe. You just came up with half a dozen excuses for why you can’t possibly run for a local office. The kids are in sports and that takes up a lot of time. You can’t afford to make effort, financially or time-wise. You hate speaking in public. Your life is far too busy for elected office. You don’t need one more thing to do.

On and on and on.

If you just used any of those excuses, take this one moment to understand that every time you complain about the state of politics and politicians, you are part of the problem. Good people won’t run, for all the reasons you just thought of. So who does that leave?

Stop complaining about the quality of our politicians if you can’t summon the stones to run yourself.

All that being said, if you want to protect your way of life from all the icky Californians coming your way, you’re going to have to shore up your political offices. Now.

I mean, right now. Look around you. Look at all the unrest and angst at local levels across the nation. Parents are forced to protest at school board meetings, barbers have to protest on capitol steps, citizens are showing up to city council meetings to protest in droves. Why? Because good people like you sat out local elections, thinking someone else would do the job. As it turns out, the “someone else” to do the job were left-wing progressives who love government and love the idea of serving in government in perpetuity.

You let it happen. You thought you were too good for public service (and you probably are) but the problem is that the people you left it to are simply not good enough.

I’m not suggesting you run for senate or congress. There are a ton of elected positions in your municipalities. I would bet you don’t know half of them. Take a look. Do a google search of available offices and choose something.

Get in the game.

You are not a bystander. You are a citizen. Quit complaining and be one.

It’s our only hope.