Multiple shutdown messages journalctl with volatile logs (?)

[kokoko3k]

Hi guys, i'm running an installation of archlinux arm on a rasperry pi b+
There are multiple "Reached target Shutdown." in my logs:
$this->bbcode_second_pass_code('', '
pi ~ # journalctl | grep -15 "Reached target Shutdown."
lug 17 11:29:09 pi iodined[332]: Listening to dns for domain j999.us.to
lug 17 11:29:09 pi systemd[1]: Reached target Multi-User System.
lug 17 11:29:09 pi systemd[1]: Starting Multi-User System.
lug 17 11:29:09 pi systemd[1]: Reached target Graphical Interface.
lug 17 11:29:09 pi systemd[1]: Startup finished in 4.019s (kernel) + 28.828s (userspace) = 32.847s.
lug 17 11:29:09 pi systemd[1]: Starting Graphical Interface.
lug 17 11:30:26 pi sshd[348]: pam_unix(sshd:session): session opened for user root by (uid=0)
lug 17 11:30:26 pi systemd-logind[216]: New session c2 of user root.
lug 17 11:30:26 pi systemd[1]: Started Session c2 of user root.
lug 17 11:30:26 pi systemd[1]: Starting Session c2 of user root.
lug 17 11:30:26 pi sshd[348]: pam_unix(sshd:session): session closed for user root
lug 17 11:30:27 pi systemd-logind[216]: Removed session c2.
lug 17 11:30:58 pi sshd[315]: pam_unix(sshd:session): session closed for user root
lug 17 11:30:58 pi systemd-logind[216]: Removed session c1.
lug 17 11:30:58 pi systemd[1]: Stopping User Manager for UID 0...
lug 17 11:30:58 pi systemd[317]: Reached target Shutdown. <--------------------- (!?)
lug 17 11:30:59 pi systemd[317]: Starting Shutdown.
lug 17 11:30:59 pi systemd[317]: Stopped target Default.
lug 17 11:30:59 pi systemd[317]: Stopping Default.
lug 17 11:30:59 pi systemd[317]: Stopped target Basic System.
lug 17 11:30:59 pi systemd[317]: Stopping Basic System.
lug 17 11:30:59 pi systemd[317]: Starting Exit the Session...
lug 17 11:30:59 pi systemd[317]: Stopped target Paths.
lug 17 11:30:59 pi systemd[317]: Stopping Paths.
lug 17 11:30:59 pi systemd[317]: Stopped target Timers.
lug 17 11:30:59 pi systemd[317]: Stopping Timers.
lug 17 11:30:59 pi systemd[317]: Stopped target Sockets.
lug 17 11:30:59 pi systemd[317]: Stopping Sockets.
lug 17 11:30:59 pi systemd[317]: Received SIGRTMIN+24 from PID 356 (kill).
lug 17 11:30:59 pi systemd[318]: pam_unix(systemd-user:session): session closed for user root
lug 17 11:30:59 pi systemd[1]: Stopped User Manager for UID 0.
--
lug 17 12:28:03 pi systemd[426]: Reached target Sockets.
lug 17 12:28:03 pi systemd[426]: Starting Sockets.
lug 17 12:28:03 pi systemd[426]: Reached target Paths.
lug 17 12:28:03 pi systemd[426]: Starting Paths.
lug 17 12:28:03 pi systemd[426]: Reached target Timers.
lug 17 12:28:03 pi systemd[426]: Starting Timers.
lug 17 12:28:03 pi systemd[426]: Reached target Basic System.
lug 17 12:28:03 pi systemd[426]: Starting Basic System.
lug 17 12:28:03 pi systemd[426]: Reached target Default.
lug 17 12:28:03 pi systemd[426]: Startup finished in 208ms.
lug 17 12:28:03 pi systemd[1]: Started User Manager for UID 0.
lug 17 12:28:03 pi systemd[426]: Starting Default.
lug 17 12:28:04 pi sshd[424]: pam_unix(sshd:session): session closed for user root
lug 17 12:28:04 pi systemd-logind[216]: Removed session c3.
lug 17 12:28:04 pi systemd[1]: Stopping User Manager for UID 0...
lug 17 12:28:04 pi systemd[426]: Reached target Shutdown. <--------------------- (!?)
lug 17 12:28:04 pi systemd[426]: Starting Shutdown.
lug 17 12:28:04 pi systemd[426]: Stopped target Default.
lug 17 12:28:04 pi systemd[426]: Stopping Default.
lug 17 12:28:04 pi systemd[426]: Stopped target Basic System.
lug 17 12:28:04 pi systemd[426]: Stopping Basic System.
lug 17 12:28:04 pi systemd[426]: Stopped target Sockets.
lug 17 12:28:04 pi systemd[426]: Stopping Sockets.
lug 17 12:28:04 pi systemd[426]: Stopped target Paths.
lug 17 12:28:04 pi systemd[426]: Stopping Paths.
lug 17 12:28:04 pi systemd[426]: Stopped target Timers.
lug 17 12:28:04 pi systemd[426]: Stopping Timers.
lug 17 12:28:04 pi systemd[426]: Starting Exit the Session...
lug 17 12:28:04 pi systemd[426]: Received SIGRTMIN+24 from PID 432 (kill).
lug 17 12:28:04 pi systemd[427]: pam_unix(systemd-user:session): session closed for user root
lug 17 12:28:04 pi systemd[1]: Stopped User Manager for UID 0.
')

Nothing strange, you could say, but my logs are stored on volatile memory, so the journal you see there is what happened since the pi has been powered on, see:

$this->bbcode_second_pass_code('', '
pi ~ # date
ven 17 lug 2015, 13.35.32, CEST
pi ~ # uptime
13:35:34 up 2:06, 1 user, load average: 0,05, 0,07, 0,05
')

To summarize, the pi has been booted at about 11:30, and at 13:30 it says it has 2 Hours of uptime.
Int that time it says in the log that it reachet the shutdown target 2 times, at 11:30:58 and at 12:28:04.
How is that possible?

I've rebooted the pi this morning, but before that, those strange entries were flooding the log.

How is that possible? Someone has an explanation?

Thanks.