Hi, was my email not coming through? Regards.
On Tue, Sep 12, 2023 at 12:06 PM Renjaya Raga Zenta < renjaya.ze...@formulatrix.com> wrote: > Hi, > > We have custom embedded device using SD Card as the main storage. > I think there are some concerns regarding how journald write the > logs, that may cause massive write amplification and that's bad for > a standard SD Card. > > Journald has Storage= option, I could use Storage=volatile and > ForwardToSyslog=yes then the disk writes seems acceptable. I could still do > systemctl status and journalctl, but the logs won't be available the > next reboot. > > Journalctl has --flush command, to flush any log data stored in > /run/log/journal/ into /var/log/journal/. It also has --relinquish-var > command, to do the reverse operation of --flush. > > Correct me if I'm wrong, if I do journalctl --flush, journald will write > in bulk, isn't it? So the write amplification has less effect. If it's > true, then I think periodically switching journald storage may help. > > 1. First, I set Storage=volatile > 2. After a while, I change it to Storage=persistent or Storage=auto, > then journalctl --flush (is restarting systemd-journald necessary?) > 3. Then, I change it again to Storage=volatile and journalctl > --relinquish-var (again, is restarting systemd-journald required?). > > So, is this a good approach? Or is my assumption is wrong. Please kindly > advise. > > If it isn't wrong, the next question is when should I switch from /run to > /var? The /run is using tmpfs, so it's in memory. I need to do the > switch before the journal log size in /run up to 50 MB for example. How > to do that? > > > Thank you. > >
