On Wed, 9 Apr 2014, Anders Olsson wrote:
Hi,
I'm wondering about how and if at all RSyslog handles voluntary stop
signals: TSTP. I have not been able to find any concrete information on
this, but maybe my google-fu is weak.
If there is no voluntary stop handling, how about mandatory stop signals:
STOP? How will the program behave? My expectation is that it will not
handle any incoming messages, and in the case of UDP they will be lost.
I'm running RSylog 7.4.4 on x86_64 embedded Linux.
The reason I'm wondering this is because I have the need to move the
location rsyslog writes to during the boot phase. RSylog is started early
in the boot phase, when this particular system has no persistent storage
area mounted - the logs go into ramdisk. Later in the boot phase network
storage is attached. At this point, I would like to be able the halt
RSyslog from writing to file, so that the logs on ramdisk can be moved, and
then continue to be appended at the new location. Just sending a HUP signal
to rsyslog could cause out of order or lost logs, depending on the order of
doing move compared HUPing.
move vs HUP should always be that you move the file then send the HUP, but only
on the same filesystem.
but if I understand what you are doing, you are trying to do
mv /ramdisk/dir/file /ramdisk/dir2/file
ln -s /realdisk/dir /ramdisk/dir
mv /ramdisk/dir2/file /ramdisk/dir/file
The problem is that when you move the file from one filesystem to another while
something is writing to it, you will always have a race condition between
writing to the file and the copy of the file.
In addition, since rsyslog only creates a file as-needed, it could create a file
as you are doing the link.
Thinking about this in 'blue sky' view, I see two approaches to deal with this
1. pause rsyslog output while you do the shuffling
2. tell rsyslog to move it's output from one place to another instead of
switching storage under it.
It sounds like you are looking at #1. I'm not sure exactly what rsyslog does
(especially since there are multiple threads, you may be able to signal
individual threads, but you can end up blocking if you pause a thread that holds
a lock)
for #2, you could use global variables in v8 and dynamic filename templates to
have rsyslog start logging to one place, and then change to log somewhere else.
The problem is what to do with the logs from the ramdisk, and I think my answer
to that is treat them like rotated logs
David Lang
Any ideas on this would be much appreciated.
Best Regards
Anders
_______________________________________________
rsyslog mailing list
http://lists.adiscon.net/mailman/listinfo/rsyslog
http://www.rsyslog.com/professional-services/
What's up with rsyslog? Follow https://twitter.com/rgerhards
NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of
sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T LIKE
THAT.
_______________________________________________
rsyslog mailing list
http://lists.adiscon.net/mailman/listinfo/rsyslog
http://www.rsyslog.com/professional-services/
What's up with rsyslog? Follow https://twitter.com/rgerhards
NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of
sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T LIKE
THAT.
