Re: btrfs constant background write activity even at idle

[Stefan Priebe <s.priebe@xxxxxxxxxxxx>]

Am 04.12.2013 20:25, schrieb Sage Weil:
> On Wed, 4 Dec 2013, Stefan Priebe wrote:
> > Hi Sage,
> >
> > Am 04.12.2013 17:13, schrieb Sage Weil:
> > > Hi James,
> > >
> > > Can you generate an OSD log with 'debug filestore = 20' for an idle period?
> >
> > i had reported something very similiar with no result to zendesk (#702).
>
> Were you also seeing the ceph-osd process show up in iotop while idle?
> That's the bit that concerns me.

Can't say this but if you look at the image in zendesk - you see the 
btrfs one has constantly 100Mb/s no up and downs.

And the xfs ones have just a few mb/s while running 3.10.19.

Greets,
Stefan

> sage
>
> > Stefan
> >
> > > Thanks!
> > > sage
> > >
> > >
> > >
> > > James Harper <james.harper@xxxxxxxxxxxxxxxx> wrote:
> > >
> > >      I have been testing osd on btrfs, and the first thing I notice is that
> > > there is constant write activity when idle.
> > >
> > >      The write activity hovers between 5Mbytes/second and 30Mbytes/second,
> > > and averages around 9Mbytes/second (as determined by iostat -x 30). On
> > > average, iostat is showing around 90 w/s, and 25% util.
> > >
> > >      There were two OSD's on this server running btrfs and both were behaving
> > > like this. I changed one back to xfs last night and it's not showing any
> > > write activity at idle now.
> > >
> > >      There is no matching write activity on the journal device, but the high
> > > writes stop when I kill the OSD process.
> > >
> > >      kworker, ceph-osd, and btrfs-cleaner processes feature highly in iotop
> > >
> > >      Is this normal? And is it a problem, or just btrfs doing background
> > > writes for some reason?
> > >
> > >      I'm running dumpling on Debian, fwiw.
> > >
> > >      Thanks
> > >
> > >      James
> > >
> > >      ------------------------------------------------------------------------
> > >
> > >      ceph-users mailing list
> > >      ceph-users@xxxxxxxxxxxxxx
> > >      http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> > >
> > >
> > > --
> > > Sent from Kaiten Mail. Please excuse my brevity.
> > >
> > >
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