[collectd] dpkg stalling on a loaded collectd aggregator

Shanker Balan mail at shankerbalan.net
Mon Jul 11 13:07:15 CEST 2011


Hello,

Trent W. Buck wrote,
> > I think I am running into the same problem as described here.
> > http://administratosphere.wordpress.com/2011/05/13/linux-kernel-sync-bug/
> 
> I see you already mentioned force-unsafe-io; here's my notes on the
> issue (encountered with a dozen LXC VMs which, sharing a kernel, all
> get synced together).
> 
> 
> This is because dpkg agressively flushes itself to disk.  This is
> especially prevalent in the Ubuntu 10.04 version, which calls sync
> instead of fsync because "fsync is too slow" or some such bullshit.
> 
> The problem first arose ca. 1.15.5.6ubuntu2.  Current versions have
> --force-unsafe-io to get the old behaviour, which you can put in
> dpkg.cfg (sans leading hyphens); they should also behave substantially
> better even without this.
> 
> As force-unsafe-io is absent from 10.04, one must grab eatmydata (from a
> later release) and replace dpkg with a wrapper that uses it:
> 
>     aptitude install eatmydata -yq
>     dpkg-divert --rename /usr/bin/dpkg
>     cat >/usr/bin/dpkg <<EOT && chmod +x /usr/bin/dpkg
>     #!/bin/sh
>     exec eatmydata /usr/bin/dpkg.distrib "\$@"
>     EOT

My SA guys decided to move to a newer kernel from
http://www.ubuntuupdates.org/ppa/kernel-ppa?dist=lucid.

They "claim" it fixes it for them. :)


-- 
http://shankerbalan.net/



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