Journalctl on SD card

Technical Support
1

Hello Toradex Team,

I’m using imx8mm with dahlia board, DSI display with DSI-DSI adaptor and 5.15.148-6.6.0-devel+git.23a8e831749d.
This is more linux problem tham torizon but we want the journalctl logs to be saved on the SD card.
We have a script periodically to store them on the SD card, bue we think there is a better way to configure journalctl and save them in the SD card instead of copy them periodically.
Can you help us achieve this?

2

Dear @peterz,

Thank you for contacting us. We recently made a blog post on our developer page which talks about persistent journald logging.

I believe this might be what you are looking for and you should be able to log the data to you SD card either through symlink or directly to the mounted storage.

Please let me know how you fare with this.
Best regards,
Collin

3

Hello @collin.tx ,
I’ve already encountered that page, but only alows us to have persistent logging on the flash.
Nothing related to change the journal source the and external SD card.
Can you give more details on how to do it?

4

Hi @peterz,

You are indeed correct. This should be possible be first mounting the SD card:

sudo mkdir /mnt/sdcard
sudo mount /dev/mmcblk0p1 /mnt/sdcard  # Adjust device paths to requirments

by default journalctl should store logs in /var/log/journal. To modify the storage location you can change the systemd journal configuration by editting journald.conf at etc/systemd/journald.conf. In there you will have to change the Storage property to persistent.

In order to change the location you can create a symlink to your SD card. At the same time you can create a backup of your current directory:

sudo mv /var/log/journal /var/log/journal.bak  # Backup current journal directory
sudo ln -s /mnt/sdcard/journal /var/log/journal

This command redirects the entries:

sudo mkdir /mnt/sdcard/journal

Also make sure you set the permissions on your SD card correctly:

sudo chown -R systemd-journal:systemd-journal /mnt/sdcard/journal
sudo chmod -R 2755 /mnt/sdcard/journal

Restarting your systemd-journald should apply the changes you made:

sudo systemctl restart systemd-journald

I have not tested this myself. Could you please try this on your side and let me know if you are successful or not?

Best regards,
Collin

5

Dear @peterz,

I just saw that this thread is a private message. Is there a reason behind that? Would you mind if we made this a public thread so others can read up on it, if necessary?

Best regards,
Collin

8

Dear @peterz,

have you been able to give the previous suggestion a try? :slight_smile:

Best regards
Collin