Author Archives: Jay Jay

About Jay Jay

Hi there. My name is John Elliot V. My friends call me Jay Jay. I talk about technology on my blog at blog.jj5.net and make videos about electronics on my YouTube channel @InTheLabWithJayJay.

Filter replacement on Dyson HP02

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Note to self: to replace the filter on a Dyson HP02:

  1. Turn off and unplug the Dyson HP02 unit.
  2. Remove the filter. Turn the base of the machine to access the filter. Then press the two buttons on the sides of the machine to release the filter.
  3. Clean or replace the filter. You can wash the filter with cold water. Do not use detergent or soap. Rinse the filter under the water until it’s clean and then let it dry for at least 24 hours in a warm place. It’s important that it’s completely dry before you put it back into the machine. If the filter is too dirty or damaged, it might be best to replace it with a new one.
  4. Replace the filter. Once the filter is completely dry, place it back in the machine. It should click into place.
  5. Reset the filter indicator. Plug in and turn on your device. Hold down the ‘standby ON/OFF’ button for 6 seconds on the remote to reset the filter indicator.

Note: you hold down the button on the *remote* not on the unit itself.

Data corruption

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Oh, yuck. ZFS-8000-8A. :(

-------------------
Mon May 29 16:23:47 [bash:5.2.15 jobs:0 error:0 time:35]
root@charm:/home/jj5
# zpool status -v
  pool: fast
 state: ONLINE
status: One or more devices has experienced an error resulting in data
        corruption.  Applications may be affected.
action: Restore the file in question if possible.  Otherwise restore the
        entire pool from backup.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-8A
config:

        NAME                                              STATE     READ WRITE CKSUM
        fast                                              ONLINE       0     0     0
          mirror-0                                        ONLINE       0     0     0
            nvme-Samsung_SSD_990_PRO_2TB_S6Z2NJ0W215171W  ONLINE       0     0     2
            nvme-Samsung_SSD_990_PRO_2TB_S6Z2NJ0W215164J  ONLINE       0     0     2

errors: Permanent errors have been detected in the following files:

        /fast/vbox/218-jj-wrk-8-charm-prod-vbox/218-jj-wrk-8-charm-prod-vbox.vdi
-------------------

Target then source

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I’m surprised it took me this long to figure this out. But there’s a very big problem with a command like this:

rsync var/data/ target:/var/data/

The problem is that in order to type that command, you first have to type the first part of the command, which includes this command:

rsync var/data/ target:/

That first part of the command is in fact a valid command, and if you pressed ENTER accidentally before you had finished typing the whole command, then rsync would begin to replace your entire root file system with the contents of var. That’s the sort of thing that will ruin your day.

So from now on, when I write command-line tools, I will nominate the target *before* the source, and if both the target and source are not specified then I will return an error.

p.s. Yes, the reverse problem exists, that when you nominate the target first you can still fuck up with the source, but given that you are operating on the target from the source, if you get the source wrong, you can just fix your command and run it again and it will be fixed up.

Watching temperature on ‘charm’

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Note to self: run these commands to watch NVMe, GPU, and CPU temperatures on ‘charm‘:

watch sudo sensors
watch sudo nvme smart-log /dev/nvme0
watch sudo nvme smart-log /dev/nvme1
watch sudo nvme smart-log /dev/nvme2
watch sudo nvme smart-log /dev/nvme3

These sensors were enabled with:

sudo apt install nvme-cli
sudo apt install lm-sensors
sudo sensors-detect