tar to other host

tar to other host

Post by Mikhail Ivan » Fri, 04 Jul 2003 23:00:01



I found in tar manual (RHL 7.3) that tar is possible to write to tape
on another host with
tar ... -f HOSTNAME:F command. But what service need to run on
HOSTNAME ?
 
 
 

tar to other host

Post by Barry Margoli » Sat, 05 Jul 2003 00:04:42




>I found in tar manual (RHL 7.3) that tar is possible to write to tape
>on another host with
>tar ... -f HOSTNAME:F command. But what service need to run on
>HOSTNAME ?

I think it uses the shell server, like rsh does.

--

Level(3), Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

 
 
 

tar to other host

Post by James T. Denni » Mon, 07 Jul 2003 17:50:10



> I found in tar manual (RHL 7.3) that tar is possible to write to tape
> on another host with
> tar ... -f HOSTNAME:F command. But what service need to run on
> HOSTNAME ?

 That would be the rexec/rcmd protocol.  Don't do that: use ssh

        tar czBSlvf - .... | ssh $HOSTNAME 'buffer -o /dev/nst0'

 ... or something like that (depends on your exact needs.

--

Jim Dennis,
Starshine: Signed, Sealed, Delivered

 
 
 

tar to other host

Post by Doug Freyburg » Wed, 09 Jul 2003 00:37:53




> > I found in tar manual (RHL 7.3) that tar is possible to write to tape
> > on another host with tar ... -f HOSTNAME:F command. But what service
> > need to run on HOSTNAME ?

> I think it uses the shell server, like rsh does.

At layer 4, socket, it is the "shell" service rexecd "shell 514/tcp cmd".

At layer 7, application, it is the rmt application originally designed for
rdump, ufsdump and so on.

So you must have the shell service turned in (x)inetd and the rmt
application installed (it is by default on most systems), the permissions
opened so you can do "rsh HOSTNAME pwd", and the target .cshrc not broken
so the response is nothing but the home directory without any errors or
other output.

 
 
 

1. Wanted: rcmd host tar x_?_vqf file.tar file1 ... fileN | tar xvf -

[X-posted to c.u.sco.misc & c.sys.sun.misc, no Followup-To set, I'll
check'em both]

Situation:

SCO v4.2 box as digital voice recorder, archiving VOX-files to Network
Jukebox Controller (basically HP MO Jukebox with 16 slots) running SunOS
4.1.3 sparc (sun4c). NJC is used for general backup/archive for whole
network. Size
of each archive tar-file is 300 MB, containing about 2500 VOX-files. So
far so good. But when it comes to user requesting old calls to be
replayed, he/she must wait a bit. At the moment, the restoring process
(say, of 100 VOX-files) is done with the following:

rcmd NJC cat archiveN.tar | tar xvqf - ${files_to_restore}

which is CPU time and network bandwidth wasting, if the files are not
stored at the beginning of archive ('tar ..q' - quits immediately when
all files are extracted). On average, the NJC must read 150 MB from MO or
cache and send it to the SCO box over network, even if only one file/call
is requested. Network and SCO box are very busy, so it may even take about
half an hour. It isn't really bad (users seldom complain about it), but it
could be much faster.

I'm about to work around it with something like this:

rcmd NJC "(
  taroffs archive.tar ${files_to_extract} | while read offset nbytes
  do
    dd < archive.tar iseek=$((offset/512)) count=$((nbytes/512))
    # OK, If SunOS 4.1.3's 'dd' does not support
    # 'iseek' or smthg like that, I will use my tool:
    # fildes archive.tar,${offset} : dd count=$((nbytes/512))
  done
)" | tar xvf -

Yes, this needs utility `taroffs`, which would print out offsets and sizes
for the specified files in the given archive. No problem, but:

The question is:

before I will code it (`taroffs`), I'd like to know, whether anyone knows
of some tar-like app, which has the option, which is missing in the
${subject}. Instead of restoring the files to disk, it should extract the
files to std. output as a smaller tar-archive. Note that it must support
also the 'q' option mentioned above and of course it must be able to
*lseek()* (in the archive) over files (not *read()* them), which are not
of interest. Otherwise, such option would be useless in this situation.

I'm looking either for SunOS 4.1.3 sparc binary or sources, which I would
be
able to compile on SunOS 4.1.3 (sun4c) or 5.[34] (sun4m/sparc).

Any other solution ?
No, NFS isn't part of SCO v4.2 Open Desktop Lite 3.0.0.

Thanks for reading this far and for your time.

--
Radek Tomis

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