[Discuss] du question

[jdm at moylan.us (dan moylan)]

dale worely writes:
> dan moylan <jdm at moylan.us> writes:
> > 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[1631] du -s *
> > 35G	20170607-120002-419
> > 86M	20170607-230005-357

> My first guess is that you have a version of du that attempts to not
> count a file twice if there are two links to it.  Since the two
> directory names ultimately link to many of the same files, the second of
> them will have an artificially low disk usage total.

> The way to check this is to run du on these directories in different
> ways.  This method will be free of the effect that I suspect:

>     $ du -s 20170607-120002-419
>     $ du -s 20170607-230005-357

> Do they produce similar values?  Or consider

>     $ du -s 20170607-230005-357 20170607-120002-419

> In this case, 20170607-120002-419 appears *second* and should have a
> total much smaller than the total reported in your example.

i'm not sure that i fully understand, but you are obviously
correct:

> moylan 1[1672] ls
> 20170607-120002-419/  20170607-230005-357/  20170608-120007-246/  b1*  last_snapshot@
> moylan 1[1673] du -s 20170607-120002-419/  20170607-230005-357/  20170608-120007-246/
> 35G	20170607-120002-419/
> 86M	20170607-230005-357/
> 80M	20170608-120007-246/
> moylan 1[1674] du -s 20170607-230005-357/  20170608-120007-246/
> 35G	20170607-230005-357/
> 80M	20170608-120007-246/
> moylan 1[1675] du -s 20170608-120007-246/
> 35G	20170608-120007-246/

interesting -- thank you.

ole dan

j. daniel moylan
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jdm at moylan.us
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