Ramlog

http://habrahabr.ru/post/272279/

/usr/bin/ramlog :

#!/bin/sh
. /lib/lsb/init-functions

start() {
    log_begin_msg "RAMLOG: Read files from disk.."
    tar xfz /var/ram_log.tar.gz -C /
    log_end_msg 0
}

stop() {
    log_begin_msg "RAMLOG: Write files to disk.."
    tar cfz /var/ram_log.tar.gz --directory=/ var/log/
    log_end_msg 0
}

case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    flush)
        stop
        ;;
    *)
         echo "Usage: $0 {start|stop|flush}"
         exit 1
esac

chmod +x /usr/bin/ramlog

/etc/systemd/system/ramlog.service :

[Unit]
Description=Ramlog
After=local-fs.target
Before=cron.service syslog.service

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/bin/ramlog start
ExecStop=/usr/bin/ramlog stop

[Install]
WantedBy=multi-user.target

/etc/crontab:

#flush log to disk every 2h
0 */2 * * * /usr/bin/ramlog flush >/dev/null 2>&1

/etc/fstab :

tmpfs /var/log tmpfs nodev,nosuid 0 0

insserv
systemctl enable ramlog.service
systemctl start ramlog.service