[CentOS] slow usb hard disk performance.

[Matt Hyclak]

On Tue, Dec 06, 2005 at 05:01:28PM -0600, Les Mikesell enlightened us:
> > > The really brilliant part of amanda is the way it schedules the
> > > mix of full and incremental runs each night to fill a tape of
> > > a given size.  This works nicely when you have a large number
> > > of small filesystems (relative to the tape size) but falls down
> > > badly when a single full nearly fills the tape because it will
> > > start streaming some small runs that are finished first, then
> > > the big one won't fit, and even during amflushes it doesn't
> > > know enough to put the big run on the tape first so you end up
> > > with the small ones that can be grouped in a later amflush. The
> > > tape spanning change may help a lot with this.
> > 
> > You can also adjust the dumporder parameter to coerce amanda into doing all
> > the biggest dumps first, or the longest dumps to complete, etc. etc.
> 
> But if you dump to holding disk, dumporder controls starting the
> runs to disk.  Hmmm... Maybe 'taperalgo biggestfit' is what I what
> but I don't see how that can work until the bigger dumps are finished
> and the small ones are going to finish first. At least it should help
> with flushes.  I guess I should read the docs every decade or so. I
> don't think those options were there the last time I looked.

Right, that's what I was talking about. If you set dumporder to some number
of T's larger than "inparallel", then you will have lots of big dumps start
and no little ones can start before them.

Matt

-- 
Matt Hyclak
Department of Mathematics 
Department of Social Work
Ohio University
(740) 593-1263