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From: Alexandros Perdikomatis <menippos@otenet.gr>
Organization: UNKNOWN ORGANIZATION
To: "Nigel J. Andrews" <nandrews@investsystems.co.uk>
Subject: Re: Database backup
Date: Mon, 20 Jan 2003 09:37:03 +0200
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Cc: pgsql-help@postgresql.org, "D'Arcy J.M. Cain" <darcy@druid.net>,
	pgsql-interfaces@postgresql.org
References: <Pine.LNX.4.21.0301191820010.3067-100000@ponder.fairway2k.co.uk>
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Message-Id: <200301200937.03806.menippos@otenet.gr>

=CE=A3=CF=84=CE=B9=CF=82 =CE=9A=CF=85=CF=81 19 =CE=99=CE=B1=CE=BD 2003 20:2=
3, =CE=BF/=CE=B7 Nigel J. Andrews =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
> On Sun, 19 Jan 2003, Alexandros Perdikomatis wrote:
> > =C3=93=C3=B4=C3=A9=C3=B2 =C3=8A=C3=B5=C3=B1 19 =C3=89=C3=A1=C3=AD 2003 =
04:59, =C3=AF/=C3=A7 D'Arcy J.M. Cain =C3=9D=C3=A3=C3=B1=C3=A1=C3=B8=C3=A5:
> > > Redirecting to help list as it seems more appropriate.
> > >
> > > On Saturday 18 January 2003 09:17, Alexandros Perdikomatis wrote:
> > > > Question: Am I too stupid to use tar?
> > >
> > > I'm sure not but you may misunderstand what tar does.  Tar is for
> > > storing a collection of files into an archive.  It expects to find the
> > > list of files on the command line in one form or another.  If you don=
't
> > > write to a file first then all you have is a stream of data, not a
> > > file.
> > >
> > > > Some time I had no space on the filesystem to copy all the data in
> > > > command mode (pg_dump) so I thought to pipe pg_dump to tar using a
> > > > scsi tape archiver as output (/dev/rmt0).
> > > > Why doesn't work?
> > >
> > > What exactly was the problem?  You may just have a device selection
> > > issue. What system is this on?
> >
> > Thanks for the reply.
> > I think I understand what you mean, I just thought that instead of a fi=
le
> > input, we could have a pipe input.
> > It runs on a SuSE linux 6.4 (you may ask why this old version, I updated
> > what was necesary, I like it becouse I have full greek support) and the
> > archiver is an old conner DDS-2 scsi tape streamer which is known on the
> > operating system as /dev/st0 by the kernel whith a symbolic link to
> > /dev/rmt0. When I pg_dump on a file, of cource there's no problem. I
> > restore also correctly.
> > But I would like to pipe this procces. For example: if we type the
> > command: # tar cvf /dev/rmt0 *
> > we're going to have all the files in the tree below to the tape.
> > How can I pipe the output of the pg_dump to it?
>
> Well, you could do:
>
> pg_dump ... > /dev/rmt0
>
> or if you want to set block size:
>
> pg_dump ... | dd of=3D/dev/rmt0 obs=3D1k
>
> Basically, you're trying to make it too complicated, tar will archive one
> file but would you really use something like:
>
> tar -cf archived-file.tar unarchived-file
>
> unless the unarchived-file name was generated automatically and it just so
> happened that only one file existed at that time?
>
> If you really do want something tar try cpio instead.

Thanks for the information, I should think about piping to dd... thanks aga=
in.=20
The idea of cpio looks more interesting becouse we could have a multivolume=
=20
archive I suppose.

one more time thanks,

Alexandros