bsdtar vs. NFS: Couldn't visit directory: No such file or directory

David Wolfskill david at catwhisker.org
Wed Nov 26 11:04:15 PST 2008


On Wed, Nov 26, 2008 at 10:49:24AM -0800, Tim Kientzle wrote:
> ...
> >I then see that tar(1) took 1924.05 seconds to do this, and exited with
> >a status code of 0.  (I ran it under the auspices of /usr/bin/time.)
> 
> I agree that this does seem wrong.

Thank you: I managed to acquire a cold or some such thing, so nothing
between my ears is working right, and I was wondering if I'd managed
to completely lose track of reality, there....  :-}

> Since you explicitly called out the time required for the
> operation, did you have any concerns about the performance?

Probably, but the first order of business would seem to be a matter of
ensuring proper operation.

That done, I expect that NFS performmance (vs. that of tar(1)) will be a
gating factor -- but also fully expect to measure & report.  :-}

> >* Is it both intentional and appropriate for tar(1) to exit with a
> >  status code of 0 in this circumstance?  The code that issues the
> >  whine is in write.c, around lines 662-663 in rev. 1.63.2.10.
> 
> As you pointed out, automated scripts need to be able
> to trust the exit code to know whether everything
> went okay.  Based on that, I would agree this is inappropriate,
> though perhaps someone has an argument to the contrary.
> I'll take a closer look.

Excellent; thank you!

> ...
> >* Am I using tar(1) appropriately?  Is there some other tool (e.g.
> >  cpio(1)) that might have more appropriate behavior for the intended
> >  usage?
> 
> tar(1) seems appropriate here.

Good; I have been using  it for similar things rather longer than I
really want to think about.  :-}

> >* Might it help to defer the compression to a point subsequent to the
> >  creation of the archive proper?
> 
> That should have no effect.

That's what I thought, but I'm sure you're familiar with the expression
"grasping at straws."  And I'm confident that you're far mor familiar
with tar(1)'s internel workings than I ever will be.  :-)

> Only odd thing I see in your usage is that the 'p' modifier
> has no effect when used with 'c'.  (bsdtar always records
> everything it can when creating the archive, limited only by
> what the underlying format can represent.)

OK -- but that ought not be harmful, yes?

> If you can reproduce this on a smaller test case, I think
> some of the folks working on NFS support might find detailed
> tcpdump output to be interesting reading.

I'll see what I can do; such details of the case that catalyzed
this thread would certainly not be appropriate for public disclosure.

I will, of course, be happy to test.  :-}

Thank you very much, Tim!

Peace,
david
-- 
David H. Wolfskill				david at catwhisker.org
Depriving a girl or boy of an opportunity for education is evil.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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