On Tue, 17 Aug 2004, Sven Rudolph wrote:
> Joshua Baker-LePain <jlb17 AT duke DOT edu> writes:
> > On Thu, 29 Jul 2004 at 11:10am, Narada Hess wrote
> > > I was having estimation timeout failures, so based on advice from this
> > > group (thanks), I increased the etimout value in amanda.conf from 600 to
> > > 6000. Yay, now my backups work! But I am frankly astonished at the fact
> > > that estimation took almost twice as long as the actual dump. Is this
> > > normal, or is there some way to speed this up?
> >
> > That depends.  The estimate phase with tar (which from below is what I
> > assume you're using) does tar cf /dev/null (among some other flags).  So
> > it just stats the files, it doesn't actually read them off the disk.  This
> > is generally *very* fast.  But if you have a case pathological to your
> > filesystem (e.g. *lots* of very small files), it can be slowed down
> > immensely.
>
> I once watched top while I had the problem here. There is a phase in
> GNU tar where it does no disc access but eats one CPU. Looks like it
> is trying to sort the index of all files (probably sorting by inode in
> order to find hardlinks).
>
> So the case is not pathological to the filesystem but to GNU tar. cpio
> avoids this; it simply writes the files out twice.

So using cpio would expand my backups by a huge factor? I have a file system
with ca. 5 million hard links for about 150000 separate files.

Gr{oetje,eeting}s,

                                                Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert AT linux-m68k 
DOT org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                                            -- Linus Torvalds