[Discuss] du question

[jdm at moylan.us (dan moylan)]

dan ritter writes:
> > On Thu, Jun 08, 2017 at 11:48:52AM -0400, dan moylan wrote:

> > > looking at the sizes of the directories created by
> > > backintime i am puzzled by a directory which shows up as
> > > 86M in one instance and 35G in another.  can someone
> > > please explain what's going on.

> > > moylan 1[1630] ls
> > > 20170607-120002-419/  20170607-230005-357/  b1*  last_snapshot@
> > > moylan 1[1631] du -s *
> > > 35G	20170607-120002-419
> > > 86M	20170607-230005-357
> > > 4.0K	b1
> > > 0	last_snapshot
> > > moylan 1[1632] du -s 20170607-230005-357/
> > > 35G	20170607-230005-357/
> > > moylan 1[1633] du -s ../
> > > 35G	../

> > I don't know backintime, but I'm guessing it uses links to
> > do file-level snapshots. Bet there's a FAQ.

> yes, true enough, and i understand that.  it's the performance
> of du that i don't understand -- look at the two cases:

> this shows the actual storage, 86M assigned to
> 20170607-230005-357.

> > moylan 1[1631] du -s *
> > 35G	20170607-120002-419
> > 86M	20170607-230005-357
> > 4.0K	b1
> > 0	last_snapshot

> this shows the primary backup storage also assigned to
> 20170607-230005-357.

> > moylan 1[1632] du -s 20170607-230005-357/
> > 35G	20170607-230005-357/

> > now why is that?

> Because hardlinks. Explained in a FAQ. I googled "backintime
> faq" and got a faq which said to try this:

> du -hd1 /media/<USER>/backintime/<HOST>/<USER>/1/

i have known from the beginning that the problem had
something to do with hard links.  i tried your suggested
command but it showed the same.

moylan 1[1658] ls
20170607-120002-419/  20170607-230005-357/  20170608-120007-246/  b1*
last_snapshot@
moylan 1[1659] du -s *
35G	20170607-120002-419
86M	20170607-230005-357
80M	20170608-120007-246
4.0K	b1
0	last_snapshot
moylan 1[1660] du -hd1 20170607-230005-357/
35G	20170607-230005-357/backup
35G	20170607-230005-357/
moylan 1[1661] du -s  20170607-230005-357/
35G	20170607-230005-357/

let it be acknowledged that i am naieve, but i expect either
of the last two commands to show 86M, and neither does,
whilst du -s * does.  still puzzled.

ole dan

j. daniel moylan
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