Authorization: NFSv4 client unable to mount exports with permission deny error

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Most of the time, it is really headache for us to locating the permission deny issue, especially under server-client model, the server only throw us the error without any further useful information, we felt really embarrassed, so the file server administrator, if they believed without implementing any tiny change to the file server now the issue goes into the unknown.

Remeber, we still have the network trace could tell us where went wrong, and we need to start from which side to locate the permission issue, that’s really helpful.

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矢志不渝 Never Give Up

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Same wisdom from different languages:










One Day I Decided To Quit……

I quit my job, my relationship, my spirituality… I wanted to quit my life.

I went to the woods to have one last talk with god

“God”, I asked,

“Can you give me one good reason not to quit?”.

His answer surprised me…

“Look around”, He said. “Do you see the fern and the bamboo ?

“Yes”, I replied.

“When I planted the fern and the bamboo seeds, I took very good care of them.

I gave them light.I gave them water.The fern quickly grew from the earth.

Its brilliant green covered the floor.Yet nothing came from the bamboo seed. But I did not quit on the bamboo.In the second year the Fern grew more vibrant and plentiful.

And again, nothing came from the bamboo seed. But I did not quit on the bamboo. He said.

“In year three there was still nothing from the bamboo seed.But I would not quit.

In year four, again, there was nothing from the bamboo seed. I would not quit.” He said.

“Then in the fifth year a tiny sprout emerged from the earth. Compared to the fern it was seemingly small and insignificant…But just 6 months later the bamboo rose to over 100 feet tall.

It had spent the five years growing roots. Those roots made it strong and gave it what it needed to survive.I would not give any of my creations a challenge it could not handle.”

He asked me. “Did you know, my child, that all this time you have been struggling, you have actually been growing roots”.

“I would not quit on the bamboo.I will never quit on you.”

“Don’t compare yourself to others.” He said.”The bamboo had a different Purpose than the fern.

Yet they both make the forest beautiful.””Your time will come”, God said to me.

“You will rise high”.

“How high should I rise?” I asked.

“How high will the bamboo rise?” He asked in return.

“As high as it can?” I questioned.”Yes.” He said, “Give Me glory by rising as high as you can.”

I left the forest and brought back this story.I hope these words can help you see that God will never give up on
you.Never, Never, Never, Give up.

Don’t tell the Lord how big the problem is, tell the problem how Great the Lord is!


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One Day I Decided To Quit……

Abnormal amount of hardware Interrupts caused high CPU issue

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Interrupts are the signals userland process want to take ownership of CPU for a while(time is very short about milliseconds) to work on its requests via a system call. When this happens, in the single core situation, CPU based on priority and scheduling algorithm to determine whether put the process to the ready queue or keep it running.

There are software interrupts and hardware interrupts to differentiate this interrupts triggered by which components. But too many interrupts will significantly degrade the performance without a doubt. Some time hardware interrupts even got worse if it kept at a high rate. Let’s do a real case review as an example, but before doing that, first, we will review some knowledge about interrupts.
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Two types of three way handshake (Connection Setup and Close)

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I still remember four years ago, one of our internal instructor Barry from Seattle to deliver training session, he mentioned three-way handshake is used as one of the technical questions to judge the technical skills of the interviewee in the most technical job interview.

Also, as an IT professional guy, I cannot emphasize enough how important it is to remember and understand these two processes as common sense in your mind since other people use this question to judge your IT skills.

The three-way handshake as one of the fundamental knowledge you should know and understand. Your solid technical skills are built on the fundamental knowledge, with the time go on, the simple technical knowledge will merge together to put you to an upper layer and form a better you.

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Application killed by oom-killer repeatedly because insufficient swap space

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We know the disk is an extension of the memory when the computer goes into insufficient memory, it will page out some pages to the disk, but do you know where it usually stored? In the Windows world, it will be dumped to the pagefile.sys which located to your default root path of your C drive, in the Linux world, there is a special partition named swap, it will send pages out there.

Why we need to page out inactive or unused pages because we don’t have enough memory to load all the application to the memory and it is unrealistic and doesn’t make sense to purchase the same size memory like your hard disk. In OS spec, there is a virtual memory (virtual space) and page table to make application itself believe all the data is loaded into the memory, actually it is not. When pages were not stored in the memory, the OS will send out interruptions of page fault to load the data from hard disk to memory, same time if the computer in memory low status it will replace some of the inactive pages to the swap space.

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How to calculate the Isilon protection overhead

Published / by Chen Ye / 2 Comments on How to calculate the Isilon protection overhead


This article is for Isilon administrators or who have the experience of Isilon product.

Isilon is a scale-out NAS storage doing an excellent work of scale out the ingesting data across the nodes within the single namespace(a very very large Peta bytes partition).

For the protection mechanism, Isilon used the RAIN(redundancy node) instead of the RAID(redundancy disk) to enhance the data protection to the next level protection.

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Python: How to print out AM/PM time format every 3 mins throughout the day

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First, let’s warm up with some functions about time/date.

The purpose for doing such kind of boring things is for implementation requirements of the scheduler I will use in Windows environment.


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