[syslog-ng] Trying to let my harddrive spin down once in a while

[Lars Stokholm]

It's not silly and in fact I've set   flush_lines (10);   in
syslog-ng.conf. I know it's not a lot, but 10 lines is far more than
crond outputs per minute, which is why I don't understand syslog-ng
writes every minute when crond is running and almost not at all when
crond is not running. Am I making any sense? :)

Lars

On Mon, Jul 11, 2011 at 7:10 PM, Paul Krizak <paul.krizak at amd.com> wrote:
>
> This may be a silly question, but have you tried setting flush_timeout()
> to some large value so that messages are queued?  Or is this not the
> behavior you seek?  It seems fairly obvious to me that if you have
> anything writing to syslog at any time, and those messages end  up in a
> file, that the kernel is going to spin up the disks and write out the
> dirty pages.
>
> The only way I can imagine to avoid this would be to queue the messages
> within syslog-ng (which won't cause any disk-backed pages in memory to
> become dirty) and only write them out at wide enough intervals that the
> kernel sees enough inactivity to spin down the disks.
>
> Paul Krizak                         7171 Southwest Pkwy MS B200.3A
> MTS Systems Engineer                Austin, TX  78735
> Advanced Micro Devices              Desk:  (512) 602-8775
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>
> On 07/11/2011 09:58 AM, Lars Stokholm wrote:
> > Hello
> >
> > On my laptop I run Arch Linux with syslog-ng and cronie (cron) among
> > other programs of course.
> >
> > I'm trying to get my harddrive to spin down automatically once in a
> > while (using hdparm).
> >
> > Me and a lot of other people both in the Arch and Ubuntu community are
> > having our attempts to do this ruined, by what first seemed to be the
> > EXT4 journalling block device (jbd2).
> >
> > After long discussions and finally a bug report (see at the bottom of
> > this mail), I think I've boiled my troubles down to be mostly about
> > syslog-ng (and possibly cronie - but I don't think so).
> >
> > No matter what I try I can't seem to get syslog-ng to stop "waking up my
> > disks" (at least that's what kernel tracing tells me). Killing the crond
> > process almost totally stops these syslog-ng writes to the disk.
> > Unfortunately I've been unable to configure my way out of it using
> > syslog-ng.conf. So my harddrive won't stay spinned down - not even for a
> > minute.
> >
> > This is what tracing the journalling gives me (see the kernel bug report
> > below for an explanaition):
> > http://pastebin.com/raw.php?i=J6BtGVrz
> >
> > As you can probably see, syslog-ng writes every minute at least. I guess
> > that's because my user crontab has a command that gets run every minute.
> > What I don't get is why syslog-ng writes to the disk, even though I'm
> > telling it not to log crond's output.
> >
> > Here is my syslog-ng.conf - as you can see I tried to output the crond
> > messages to /dev/null. I guess it works, because there are no mentions
> > of crond anywhere in /var/log anymore.
> > http://pastebin.com/raw.php?i=H02KKWPV
> >
> > Here are the discussions and the bug report I mentioned:
> > https://bbs.archlinux.org/viewtopic.php?id=113516
> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/607560
> > https://bugzilla.kernel.org/show_bug.cgi?id=39072
> >
> > I don't know if syslog-ng is causing trouble for only me, but it seems
> > unlikely.
> >
> > Regards,
> > Lars
>
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