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Cake day: July 1st, 2023

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  • In my system, the raid arrays seem to do periodic data scrubbing automatically. Maybe it’s something that’s part of Debian, or maybe it’s just a default kernel setting. I don’t think it helps much with data integrity – I think it helps more just by ensuring the continued functionality of the drives.

    When it’s running, you can type cat /proc/mdstat to see the progress.

    That command will also show you if there is a failing drive, so that you can replace it.





  • Sure. First you set up a RAID5/6 array in mdadm. This is a purely software thing, which is built into the Linux kernel. It doesn’t require any hardware RAID system. If you have 3-4 drives, RAID5 is probably best, and if you have 5+ drives RAID6 is probably best.

    If your 3 blank drives are sdb1, sdc1, and sdd1, run this:

    mdadm --create --verbose /dev/md0 --level=5 -n 3 /dev/sdb1 /dev/sdc1 /dev/sdd1

    This will create a block device called /dev/md0 that you can use as if it were a single large hard drive.

    mkfs.btrfs /dev/md0

    That will make the filesystem on the block device.

    mkdir /mnt/bigraid
    mount /dev/md0 /mnt/bigraid
    

    This creates a mount point and mounts the filesystem.

    To get it to mount every time you boot, add an entry for this filesystem in /etc/fstab




  • Any regular hex nut works just fine as a jam nut. Basically, a jam nut is when you jam two nuts together. (It is gay, because the nuts do touch.)

    And note that those nylon inserts kinda only work once. The bolt carves a thread into the insert when you insert it, so it will be weaker the second time you insert it.

    Honorable mention: cage nuts. A square nut, permanently attached to a fastener that can snap into a special square hole in a 19 inch server rack. When you tighten the bolt against the nut, it tightens against the fastener, so that the nut, bolt, and fastener are secure against the square hole.




  • Unfortunately this won’t happen until October 31st 2600. Starting on March 1st in the year 2600, the Julian calendar (popular in centuries past, and still used in a few places) will differ by 18 days from the Gregorian calendar (the current worldwide standard calendar).

    It happens that October 31st in the year 2600 lands on a Friday, and so the Julian October 13th, which lands on that same day, is also a Friday.

    There may be a sooner Friday the 13th that lands on Halloween, if you know of other obscure calendars like the Hebrew, Islamic, or Chinese calendars. I don’t know enough about those to check.


  • The easiest way to disable unnecessary services is to uninstall them with aptitude, or whichever package manager you like. Try terminating services one by one, and see if anything bad happens. If nothing bad happens, you can probably uninstall it. On the other hand, if the system does get wonky a reboot should fix it. Or, you can research the services by name and decide whether to uninstall them. (avahi-daemon for example is a good idea to uninstall.)

    To make the GUI not run, uninstall your display manager (gdm, xdm, nodm, or whatever) and uninstall your xorg server or wayland server. There may be GUI programs remaining after that, but they will only be consuming disk space, not RAM or CPU.

    If the battery is old and holds little charge, you may save a few watts by removing it and throwing it away, instead of letting the system keep it topped off.

    Get a power meter, such as a Kill-a-watt device. Then, experiment with different settings. If it’s consuming less than 30 watts, you’re probably fine. If you live in the US, one watt-year is about one US dollar (or a little more), so for every watt it consumes, that’s about how much you will pay per year for its electricity.