Data integrity – why I choose Btrfs (silent data corruption)

Not every file system do data block checksumming. And the most popular one on Linux ecosystem – ext4 file system – is one of them. That means if there is a silent data corruption occur on the disk, it may not get noticed. The corrupted data may get backed up to the off-site storage device, and by time, the backup will get corrupted after it’s been replaced by up-to-date (corrupted) version. This is potentially dangerous if the data need to be stored for a long period of time.

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Difference between Markdown and Discount

Discount is a C implementation of Markdown, and Markdown a text-to-HTML converter written in Perl. They are pretty similar but different in the following behaviours

  • Discount will replace double quote "" with “” and single and double quote ' with . Where Markdown will keep the single and double quote as-is.
  • To have a second level indentation on bullet points, Discount require two spaces, where Markdown only require one.

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Prevent accidental erasure of internal drive while using dd to write USB flash drive

It is risky to issue a command like sudo dd if=image of=/dev/sdb bs=1M due to the risk of typing sdb to something else (e.g. internal drive). If an error has been made, the internal hard drive may get erased. This post proposes a solution by using udev rules, which will allow read/write access to USB drive without sudo and no password required. These udev rules does not affect SATA-based storage devices.

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ThinkPad X280 CPU load and throttling test on Ubuntu 18.04 (bionic)

Before purchasing ThinkPad X280, I was concerned about the CPU throttling bug. It’s a bug which will throttle the CPU performance once it’s been triggered and will not restore the performance without a reboot.

I’ve developed a Ruby script for this test, and run it on X280 with i5-8250U processor. I did not reproduce the throttling issue that requires a reboot to restore the performance – whether the machine is powered by battery or connected to the power supply. However, I did discover a symptom which will under-clock the process to 123MHz under the certain load.

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