Questions regarding journal replay

[Ralf Hildebrandt]

* Eric Sandeen <sandeen at redhat.com>:
> Ralf Hildebrandt wrote:
> > * Ralf Hildebrandt <Ralf.Hildebrandt at charite.de>:
> >> * Curtis Doty <Curtis at GreenKey.net>:
> >>> Yesterday Ralf Hildebrandt said:
> >>>
> >>>> The journal replay too quite a while. About 800 seconds.
> >>>>
> >>> Were there any other background iops on the underlying volume 
> >>> devices? Like maybe raid reconstruction?
> >> I don't think so. The machine never powered off...
> > 
> > Again, 2.6.28.7 failed us and now we're encountering another journal
> > replay. Taking ages. This sucks.
> > 
> > Questions:
> > 
> > How can I find out (during normal operation) HOW MUCH of the
> > journal is actually in use?
> > 
> > How can I resize the journal to be smaller, thus making a journal
> > replay faster?
> > 
> 
> It'd be better to get to the bottom of the problem ... maybe iostat
> while it's happening to see if IO is actually happening; run blktrace to
> see where IO is going, do a few sysrq-t's to see where threads are at, etc.

We had 24GB of reading from the journal device (or 12GB if it's
512byte blocks). I wonder why?

> Can you find a way to reproduce this at will?

Yes. My users will kill me, though.

> Journal replay should *never* take this long, AFAIK.

Amen

-- 
Ralf Hildebrandt                                Ralf.Hildebrandt at charite.de
Charite - Universitätsmedizin Berlin            Tel.  +49 (0)30-450 570-155
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