Re: Perfomance problem backupscript (more details and tests)

On Sun, 2005-10-09 at 08:25, Joerg Schilling wrote:
> > tar -Gxpvf ../tar0.out
> > tar -Gpxvf ../tar1.out
> > cd ..
> > diff -r test rest
> > ---
> > Mine are identical - rest/b and contents are gone, rest/e and
> > contents are present. 

> I said that GNU tar fails with _simple_ test cases, but you did use 
> an extremely trivial case. Just follow the instructions I did send a few days 
> ago.

This test was a response to your statement (which was just above
but you deleted it):
 "There are many other problems with incrementals using GNU tar.
  GNU tar does absolutey not grok the case when a directory is
  renamed......"

The point of that test was to show that GNU tar does handle
renamed directories correctly with --listed-incremental.

I can't follow the instructions or script in your earlier
email because they refer to files that exist only
on your computer.  Do you have a self-contained script
that creates a test case that will fail?

> I did always check the latest versionof GNU tar.

The latest from the developers is often not what you
really want to run.  How about one as currently included
in a well-tested distribution?

> > If you dumped from a ufs filesytem and restored to a ufs filesystem
> > with exactly the same mount points.
> 
> ufsrestore restores to any POSIX filesystem.
> 
> Ufsump has been ported to many OS and filesystems.

GNUtar can restore to a VFAT filesystem.  It probably won't
get renamed files right in an incremental run from VFAT since
there isn't a real ctime, but I'm not sure what you can do
about that.  VFAT is still popular and necessary because
it is the only thing common across windows, linux, os/x
and other unix variations.  It is probably gaining in
popularity as USB flash drive prices drop.  And a backup
program should either do something reasonable with them
or make it clear that they can't be mounted and unmounted
arbitrarily to get contents included.

> > > How many real desaster recoveries did you do with the so created archives?
> >
> > I think there was only one that involved multiple level restores.  The
> > amanda estimates allow it to bump the levels up/down according to what
> > will fit on the tape so often you'll have a recent level 0 available
> > if you allowed enough tape capacity to catch occasional large changes.
> > I don't remember any particular real-world problems.
> 
> This answer is not related to the question. The question was related to the
> reliability of GNU tar incrementals.

After using them for many years and recovering files from old
tapes on wildly different machines, I still have no reason to
distrust them.

> As the GNU tar maintainers did chose not to reply to my bug reports in 2004,
> it cannot be fixed in an official release as the latest GNU tar release
> is from December 21st 2004.

If you gave them a test case they couldn't reproduce, I'm not
surprised the bug didn't get fixed.   I remember seeing
something about symlinks not being handled right somewhere
but didn't have enough information to reproduce it.

-- 
  Les Mikesell
    [email protected]