On Wed, Jun 27, 2001 at 03:27:29PM +1000, Ivan Rayner wrote:
> On Wed, 27 Jun 2001, Russel Ingram wrote:
>
> > On Tue, 26 Jun 2001, Gonyou, Austin wrote:
> > > Will those actions yield a tape which only has the last dump on it, or
> > > will
> > > it seek to the end of the last dump, and then start writing? If it does do
> > > that, then I'm set. As I'm led to believe that it does from Steve Lord's
> > > previous post. I just didn't see that behaviour with dump I don't think,
> > > so
> > > I'm just skeptical without getting it substantiated first. Thanks for the
> > > feedback.
> >
> > Doing it with that particular device will result in several dumps that
> > overwrite each other (I'm pretty sure). To be sure to avoid overwriting
> > individual dumps use the non-rewinding device:
>
> xfsdump will actually skip over dumps that may already exist on the tape.
> The way it works is that it will read the tape and if it finds a dump, it
> will skip past it and then do another read. It will fail if it finds
> something that is not a dump otherwise it will write after all the other
> dumps.
>
So, in other words, you don't need to use the non-rewinding device :)
An xfsdump to tape consists of a number of tape files, and the
final file is a terminator file. When you go to dump to a tape
which already has dump sessions on it, it rewinds to the start, and
if the header looks good,
then it searches through the tape for this terminator file.
It then overwrites this terminator and places one at the end when it finishes
dumping the data.
> Specifying '-o' (overwrite) disables this behaviour, causing xfsdump to
> just write wherever the tape is positioned.
>
> (If you find that xfsdump doesn't behave as advertised, please let us
> know.)
>
> > Now, since I just finally got a tape drive working on my Linux system with
> > XFS, I have a quick question for the xfsdump folks. xfsdump on Irix gives
> > sort of a progress report with percent of job done. Is there a reason
> > this is no in the Linux version?
>
> xfsdump on linux does not include threading, ie. it runs in a single
> thread. Progress reporting is a feature of xfsdump's multi-threaded mode.
> The reason the Linux version is single threaded is simply that I was moved
> onto other things before I finished the port. The only real functionality
> lost is the ability to write several tapes at once and it was felt that
> this probably wouldn't be a big issue for the Linux folk at the moment.
>
Have you tried the -p option ?
Cheers,
Tim.
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