From mboxrd@z Thu Jan  1 00:00:00 1970
From: dexen deVries <dexen.devries@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Date: Thu, 18 Nov 2010 20:44:18 +0100
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Subject: Re: [9fans] Anyone using p9p or Plan 9 venti as a more generic
	backup system?
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On Thursday 18 November 2010 20:40:13 Bakul Shah wrote:
> On Wed, 17 Nov 2010 09:44:27 PST David Leimbach <leimy2k@gmail.com>  wrote:
> > On Wed, Nov 17, 2010 at 9:23 AM, dexen deVries
> > <dexen.devries@gmail.com>wrote
> >
> > > On Wednesday 17 November 2010 18:14:35 Venkatesh Srinivas wrote:
> > > > (...)
> > > > I'd be very careful with vac -m and -a on Unix; both have been at the
> > > > root of considerable data-loss on a unix venti for me. I'd recommend
> > > > vac-ing tarballs, rather than using vac's on unix trees directly. But
> > > > your mileage may vary...
> > >
> > > could you please elaborate a bit about that data loss?
> > > traversing symlinks breaks? some files not getting read by vac at all?
> > >
> > > (I'm interested in using p9p vac+venti in similar manner, but on Linux
> > > w/ GNU stuff)
> >
> > I could imagine vac/unvac not dealing with resource forks or POSIX
> > extended attributes and such properly, as well as potentially having
> > difficulty with symlinks, but having dealt with stuff like that in
> > "xar", I don't think it's too difficult to address.
> >
> > I may need to read up on venti and see what sorts of data types it
> > supports.
> >
> >  Might be time to add some extensions?
>
> venti doesn't care but vac/unvac do deal with symlinks, fifos
> and special devices.  The problem with -a is that a
> yyyy/mmdd/ prefix gets prepended to all paths and these dirs
> are readonly (555). unvac coredumps in trying to extract
> anything under yyyy/. The real problem is that unvac needs to
> handle non-empty 555 dirs specially (like tar does).
>
> Try this on unix:
>
> mkdir -p a/b
> chmod 555 a
> tar cf - a | (cd /tmp; tar -xvf -)
> vac a | (cd /tmp; unvac -v)
>
> The basic problem is that venti & friends need some grunt work to
> make them bullet/idiot proof.

thanks ;)

--
dexen deVries


``One can't proceed from the informal to the formal by formal means.''