Fellow Sun Managers,
Thanks for your prompt and plenty of responses.
My original question was:
--- Two Solaris machines(sun_a, sun_b), and I intend to archive a directory in sun_a into a tape drive in sun_b as follows.
sun_b# tar cvfb - 20 ./dir | rsh sun_a exec dd of=/dev/rmt/0 obs=20b
And above archiving doesn't fail, but the following extraction fails.
sun_a# tar tvf /dev/rmt/0 tar: tape read error sun_a# ---
Answer: Don't use 'exec'. i.e. just 'tar .. | rsh sun_a dd ..' works.
I don't know what the difference is, but I can successfully 'tar tvf /dev/rmt/0' and 'tar xvf /dev/rmt/0' in sun_a by omitting 'exec' in 'rsh sun_a exec dd ...' when archiving. I always feel it's not good to 'rsh sun_a dd ...'(without 'exec') because it produces two processes in sun_a machine(a csh process and real dd process), but from this lesson, I found it's important not to use 'exec' in the command combination piped to rsh. Could someone please explain the reason for this tricky phenomenon ?
Vipin Gupta <Vipin.Gupta@blr.sni.de> David Thorburn-Gundlach <email@example.com> Alejandro Lopez-Valencia <firstname.lastname@example.org> Mark Heath <email@example.com> "Raymond F. Rodebaugh" <firstname.lastname@example.org> "martha.crocker" <email@example.com> firstname.lastname@example.org (Syed Zaeem Hosain) email@example.com (System Administrator) firstname.lastname@example.org (Kris Briscoe) Joel Lee <email@example.com> Michael Hill <Hill.Michael@tci.com> Glenn Satchell - Uniq Professional Services <Glenn.Satchell@uniq.com.au>
Some managers suggested to do 'dd if=/dev/rmt/0 | tar tvf -' in sun_a because one cannot use tar to read a dd archive. It also works with the archive I made with 'tar ... | rsh exec dd of...'. But the statement that one can't use tar to read a dd archive seems false, 'cause I can use tar to extract a dd archive without 'exec' in rsh command.
Best regards, Ho-Sung Song
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