I am trying to understand what journald does in relation to persistent storage of log entries. I have an SDCard setup so I am looking to keep disk writes to a minimum, but would like some persistence in logging via journald.
Out of the box (Raspbian) journald uses
Storage=auto i.e. unless there is a mount for
/var/log/journal it will simply store all logs to RAM.
The question is, if there is a mount point
/var/log/journal, does journald continue to use RAM where it can, or does it default to writing everything to disk?
If it does write to RAM primarily, what default mechanisms are setup to manage the persistence of logs?