Currently we are investigating your case. We will get back to you as soon as we have a complete answer about your questions.
Now I see how it is made volatile. Even though Storage=persistent, and /var/log/journal exists, /var/log has been made into a symbolic link to subdirectory of /var/volatile, which is a tmpfs ramdisk mountpoint.
We truly apologize for the delay in our response. We already have some updates on this case, check our notes below:
The edison-image.bbappend file in meta-intel-iot-devkit/recipes-core/images is the place where the volatile log is set up. Specifically the line immediately following the comment "# Add volatile log".
You can comment out this line and rebuild the image.
If you want to use an existing image, then you should disable volatile logs by doing something like this:
1. Comment out the line for /var/volatile/log in /etc/tmpfiles.d/00-create-volatile.conf
2. rm /var/log (deletes the existing symlink to /var/volatile/log)
3. mkdir /var/log (creates a real directory to replace the symlink just deleted)
Then reboot and logs should be persistent.