The following sections describe how to identify the type of data corruption and how to repair the data, if possible.

• Identifying the Type of Data Corruption

• Repairing a Corrupted File or Directory

• Repairing ZFS Storage Pool-Wide Damage

There's a nice lengthy post of the zfs-discuss mailing list that covers how scrub works on a raidz vdev. The gist of it is:

• read data block, compute checksum
• read checksum from disk, compare to computed checksum
• compute parity for block, compute checksum for parity block
• read checksum for parity block from disk, compare to computed checksum

If compute checksums don't match the checksums on disk, then data block is rebuilt from parity, checksums are compared, and data written overtop of the bad data block.

There are only two cases where ZFS will overwrite an existing block. The first is when updating the vdev labels at the beginning and end of each device. The second is when repairing a damaged block on disk. The key here is that the block is rewritten with its original contents meaning its checksum, which is immutable, does not need to change. This is the only valid data which can be written to this block. //

To sum it up:

Read error during normal operation = data gets reconstructed from parity and we continue
Read error during scrub = data gets reconstructed from parity plus fixed by overwriting the data on the disk? The rewrite will then rely on the disk remapping capability of the hard disk.

The National Pulse.
NEWS
Biden White House Approves Licensing Deal For Chinese Communist Party-Linked Huawei, Reversing Trump-Era Hardline.
AUGUST 24, 2021NATALIE WINTERS

The Biden White House granted the Chinese Communist Party-linked firm Huawei – which was crippled by Trump-era sanctions – licenses to purchase American auto chips, according to reports. //

The decision follows the Beijing-backed tech firm hiring several lobbyists, including the brother of Biden’s White House Counselor Steve Ricchetti and CNN guests who have pushed the Trump-Russia collusion hoax.

https://www.reuters.com/business/autos-transportation/exclusive-us-approves-licenses-huawei-buy-auto-chips-sources-2021-08-25/

we now know why Biden and his cohorts have been so careful to not criticize the Taliban and to not label them an enemy — the administration is taking orders from them.

Of course, aside from the realities on the ground in Afghanistan, this humiliation goes much further in damaging the credibility and capability of the United States. What do you think China is going to take from all this as they set their sights on Taiwan? Or the Russians who were just “punished” by the laughable sanction of banning ammo sales to Americans (a move meant to hurt American gun owners, not Putin)? You can bet Iran is getting ready to take us to the cleaners as well. //

Skeptical Techie swhitebull
a day ago
Dien Bien Phu pales by comparison to the cataclysm Biden has precipitated. We are only in the beginning phases. The enslavement and body counts are as yet incalculable. The far-reaching consequences go far beyond Kabul and Afghanistan. We know already, they stretch to the South China Sea, Japan and Taiwan. The extent of the damage and carnage on a geographic scale are yet to unfold enough to allow a meaningful forecast as to the ultimate costs

Eric Schmitt
@Eric_Schmitt
🚨Breaking: By a 6-3 vote the Supreme Court agrees with Missouri and Texas — Joe Biden’s reversal of President Trump’s Migrant Protection Proticalls or the ‘Remain in Mexico’ policy was illegal — the policy is back in effect. #BidenBorderCrisis #SCOTUS #Winning
7:37 PM · Aug 24, 2021

Bear in mind, this isn’t a full decision on the merits — this is merely a ruling that Judge Kacsmaryk’s Order will not be stayed pending the appeal on the merits. The net effect is that the Remain in Mexico policy is back in effect, unless and until the Biden Administration wins an appeal on the merits. (Note, that in today’s Order, Justice Alito found that the Administration failed to demonstrate a likelihood of success on the merits, though nothing is set in stone until the appeals process is complete.) And that, indeed, is a big win.

U235 is 5 orders of magnitude more energy than wood, and breeder Thorium had 3 orders more than that!

Checksum errors can occur transiently on individual disks or across multiple disks. The most likely culprits are bit rot or transient storage subsystem errors - oddities like signal loss due to solar flares and so on.

With ZFS, they are not of much concern, but some degree of preventative maintenance is necessary to prevent a failure from accumulation.

From time to time you may see zpool status output similar to this:

    NAME        STATE            READ  WRITE CKSUM
    zones       ONLINE             0     0     0
      mirror-0        ONLINE       0     0     0
        c1t0d0        ONLINE       0     0     23
        c1t1d0        ONLINE       0     0     0

Note the "23" in the CKSUM column.

If this number is significantly large or growing rapidly, the drive is likely in a "pre-failure" state and will fail soon, and is otherwise (in this case) potentially compromising the redundancy of the VDEV.

One thing to make note of is that checksum errors on individual drives, from time to time, is normal and expected behavior (if not optimal). So are many errors on single drives which are about to fail. Many checksum failures across multiple drives can be indicative of a significant storage subsystem problem: a damaged cable, a faulty HBA, or even power problems. If this is noticed, consider contacting Support for assistance with identification.

EXC: Joe Biden’s State Dept Halted A Trump-Era ‘Crisis Response’ Plan Aimed At Avoiding Benghazi-Style Evacuations Just MONTHS Before Taliban Takeover.

Joe Biden’s State Department moved to cancel a critical State Department program aimed at providing swift and safe evacuations of Americans out of crisis zones just months prior to the fall of Kabul, The National Pulse can exclusively reveal. //

The “Contingency and Crisis Response Bureau” – which was designed to handle medical, diplomatic, and logistical support concerning Americans overseas was paused by Antony Blinken’s State Department earlier this year. Notification was officially signed just months before the Taliban’s takeover of Afghanistan.

No matter what they say, this is a national disgrace. Americans and friendly Afghans will be left behind. The Taliban controlled access to the airport as well as setting the deadline for finishing the mission. Our troops were not allowed to leave the airport to try to find US citizens and loyal Afghans. This was not the Berlin Airlift. We’ll be damned lucky if it doesn’t turn out to be Dien Bien Phu. //

conservativecurmudgeon
11 minutes ago
Okay, we will take them at their word.

This is the greatest “airlift” since the early days of the Cold War. Of course, the Berlin Airlift was FAR more concerned with getting goods in than getting people out. But, no matter...

The reason we’ve had all three —the Cold War, the Berlin Air Lift, and now Biden’s Catastrophe in Kabul is because of the utter incompetence of the leftist worldview...

We EVEN HAD the Cold War because of the likes of Klaus Fuchs, Harry Hopkins and Alger Hiss, who were left in positions of real power —and who were handing atomic secrets to the Russians— during the reign of FDR; and, Roosevelt likely knew this, and did nothing. Roosevelt (a true classical global leftist) had a real man-crush on Stalin and all things totalitarian, and he saw nothing wrong with all the REAL Reds in his midst. If we’d had even a tithe of moderating influence of, say, an Arthur Vandenburg at Yalta, the Iron Curtain would not have likely descended to the degree it did... but, it was polluted with the likes of Edward Stettinius and Bedell Smith, and others that viewed the Russians then as the High Command views China now— strategic partners that might be a bit overbearing, but hey: those Commies get things done, right?

Not to mention: there would have been no NEED for a Berlin Airlift —had Truman been more confident in his atomic Arsenal. We had our vast numerical superiority at the time— the Russians would very likely have backed down anyway. But, again, most of the post-war high command (with the obvious exception of Curtis LeMay) was still enthralled with Papa Joe...

Which leads us to today: Joe Biden is (or, what’s left of Joe Biden) is just fine with 7th Century Primitives using the advanced technology his own countrymen paid for and developed, and that is currently being used by these Islamic barbarians to flay and martyr Americans; he rather likes strongmen and authoritarianism, and has always thought more highly of coercive groups than sovereign individuals. He’s fine if America takes a shot in the neck as long as global coercive collectivism is advanced.

It’s a straight line from FDR to Biden— and both created existential crisis that our valiant air forces had to fix.

This document is written for administrators and those who have familiarity with computing hardware platforms and storage concepts such as RAID. If you're already versed in the general failure process, you can skip ahead to how to replace a drive and repairing the pool.
Degrees of verbosity

When a drive fails or has errors, a great degree of logging data is available on SmartOS. We can drill down in more detail to help us find the underlying cause of disk failure. In descending order, these commands will present the disk failure cause in increasing verbosity:

• zpool status
• iostat -en
• iostat -En
• fmadm faulty
• fmdump -et {n}days
• fmdump -eVt {n}days

The zpool status command will present us with a high level view of pool health.

iostat will present us with high level error counts and specifics as to the devices in question.

fmadm faulty will tell us more specifically which event led to the disk failure. (fmadm can also be used to clear transitory faults; this, however, is outside the scope of this document. Refer to the fmadm man page for more information.) fmdump is much more specific still, presenting us of a log of the last {n} days of fault events. This information is often extraneous to replacing faulted disks, but if the problem is more complex than a simple single disk failure, it is extremely useful in isolating a root cause.

While the administration tries to take credit for top-line evacuation numbers, many outsiders — veterans, diplomats, NGOs and others — have been frantically coordinating to help American citizens and Afghan allies escape because the normal channels are chaotic. One such group of veterans has taken to calling themselves “digital Dunkirk” or “Task Force Dunkirk,” referring to the mass evacuation of allied troops from France in 1940.

“We are having to come up with alternatives to get people in,” said Mick Mulroy, a former defense official and CIA officer and Dunkirk member. “The sheer masses of people are making it very difficult.”

Members of these informal groups and the soldiers in the airport they are working with are increasingly frustrated by the bureaucracy and lack of support from the State Department. One person involved in the efforts shared screenshots of a chat with a soldier who expressed anger with State officials interfering at the last minute.

“They’re f---ing changing up everything because they decided to show up for the first time,” the soldier texted, after State officials changed the location for processing American citizens at the last minute.

Since Gore’s 2006 propaganda piece, there have probably been hundreds of films over the past 15 years that have focused on the global warming climate change crisis. Maybe if they’d decide on a name to call it, it might help.

Just how many more of these films do we really need? //

2017 New York Times article had this to say about the dearth of filmmaking focused on the climate crisis:

So, said Mr. Hoffman, the University of Michigan professor, we need “more movies, more TV, more music.”

“We have to touch people’s hearts on this,” he said. “It’s critical.”

Four years later, and Ms. Greta Thunberg is bemoaning the same thing.

Although agreeing with Thunberg, Nesbo acknowledged the topic is “not an easy sell,” particularly because we are in the middle of the climate crisis with no idea how it will end.

“If you look at all the crises in the world, you see that much of the storytelling doesn’t take place

Solar energy can be stored by converting it into hydrogen using hematite. //

Researchers from the Technion-Israel Institute of Technology have made a scientific breakthrough on the storage of solar energy, as reported by Energy & Environmental Science. A project led by Professor Avner Rothschild of the Technion's Faculty of Materials Science doctoral student Yifat Piekner from the Nancy and Stephen Grand Technion Energy Program (GTEP has shown that hematite can serve as a promising material in converting solar energy into hydrogen.

The process entails the use of photoelectrochemical solar cells, which are similar to photovoltaic cells, but instead of producing electricity, they produce hydrogen using the electric power (current × voltage) generated in them. The power then uses sunlight energy to dissociate water molecules into hydrogen and oxygen.

Hydrogen is easy to store and when used as fuel, does not involve greenhouse gas or carbon emissions.

The woman who’d asked the question says, “It’s fine, thanks,” but the look on her face is one of frustration.

No, Ms. Redmond, it’s not good that none of your “narratives” about “white WASP culture” are good. Aren’t we told that unless we are part of a certain ethnic group we cannot take it upon ourselves to define that culture? Well, two white women were telling you that there are many “white” cultures in the United States but you were having none of it. What would have happened if they pushed back further? They clearly did not feel safe to, and they were forced to sit there and listen to that drivel as part of their job. Will they now be vilified and targeted as not being sufficiently anti-racist? Will white students on the 23 California State University campuses be pilloried if they refuse to accept your “narratives” about a culture they’re a part of? We already know the answer to that question, but this openly hostile attitude toward one race is despicable and morally unacceptable.