All right, I think I've seen people mention the points I would have
tried to make (and I don't know any of this for sure, but it's worth a try).
Recapping the valid points:
o The tape drive wants tar. Anything involving tar-formatted stuff
going directly to tape works; hence tar -cvf /dev/nst0 or pg_dump -F t >
/dev/nst0 functioning as expected.
o gzip doesn't care. It'll zip anything. So piping any of that through
gzip into a file is just fine.
o A gzipped tar isn't tar format; it's gzip format. The tape drive
doesn't know what to do with gzip and chokes.
Additional point: It appears that your version of tar doesn't like the
syntax for reading from stdin (at least not within an su command
string). This'll be a problem for making it all happen in a one-liner,
but if you don't mind a bit of scripting and keeping some staging area
on your hard drive, script the following steps:
1) Dump from postgre through gzip into a file. Don't worry about tar
format; dump it however postgre likes it when it's time to restore.
pg_dump --make-restore-easier mydatabase | gzip [-9] tempdump.gz
(where --make-restore-easier is whatever set of flags and options makes
restoration easiest, and [-9] means optionally specify maximum gzip
compression)
2) Tar the gzipped file onto the tape drive
tar -cvf /dev/nst0 tempdump.gz
3) Delete the temporary file
rm tempdump.gz
Restoration is the reverse of backup:
Since in this stage, tar is a source rather than a sink, you should be
able to achive restoration as a one-liner:
tar -Oxf /dev/nst0 | gunzip -C | postgre_command
If that chokes for some reason, follow the reverse of backup:
1) Retrieve the gzipped file from the tape.
tar -xvf /dev/nst0
2) gunzip the result and pipe it into your favorite postgre interpreter.
gunzip -c tempdump.gz | postgre_command
3) delete the temporary file
rm tempdump.gz
Hopefully that's at least somewhat clear. :-) And helpful.
Cheers,
~Brian
Andrew Perrin wrote:
perrin:~# su postgres -c '/usr/bin/pg_dump leted | tar -czf /dev/nst0 -'
tar: -: Cannot stat: No such file or directory
tar: Error exit delayed from previous errors
----------------------------------------------------------------------
Andrew J Perrin - andrew_perrin (at) unc.edu - http://perrin.socsci.unc.edu
Assistant Professor of Sociology; Book Review Editor, _Social Forces_
University of North Carolina - CB#3210, Chapel Hill, NC 27599-3210 USA
New Book: http://www.press.uchicago.edu/cgi-bin/hfs.cgi/00/178592.ctl
On Mon, 27 Nov 2006, Joseph Mack NA3T wrote:
On Mon, 27 Nov 2006, Andrew Perrin wrote:
Thanks, but gzip actually handles tar format fine;
yes of course (doh).
o gzip handles tar format
o the tape drive wants tar format.
I don't have a tape drive to test this on, so I hope I'm not wasting
your time, but you didn't tell me what happened with
/usr/bin/pg_dump leted | tar -czf /dev/nst0 -
Joe
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