Re: Perfomance problem backupscript (more details and tests)

Les Mikesell <[email protected]> wrote:

> On Tue, 2005-08-30 at 09:28, Joerg Schilling wrote:
>
> > And it should be noted that this is badly documented (no man page)
> > and that the workaround is not mentioned at all:
> > 
> > use GNU tar -c > /dev/zero
>
> For the pathological cases where I've wanted gnutar to read
> data, then discard it, I've used  "-f - |cat >/dev/null".

This makes it slower as needed as you need to feed the pipe.

> > It is really bad practice to introduce such an implicit and hidden
> > feature into a program. Star does it the clean, obvious and easy
> > to controllable way: use star -onull if you only like to do 
> > specfic tests for size metering.
>
> On the other hand it is useless, even if good practice, to arbitrarily
> change options so that interoperation with other existing tools

Amanda people did request an option and ware a bit disappointed when the
GNU tar people implemented it this strage way....

> like amanda cannot work.  Star might now have sufficient
> awareness of incrementals to replace gnutar for amanda runs, but
> guess which I'm still using...   Are there any higher-level programs
> like amanda, backuppc, etc. that work with star?

I am not aware of them but it seems that the Amanda people are very GNU tar
centric althouth they know that GNU tar does not do what they like with
incremental backups.

> > Note that GNU tar is even buggy in it's "amanda feature" and badly
> > fails if you use this "feature" together with sparse files.
>
> Does it report the space as shown by ls -l, or what will be used
> in the modes that understand sparse files?

Try it out..... There are strange error messages and GNU tar reports the
same size as it would do without -S.

Jörg

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