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fbackup

Frances Prindle
Occasional Advisor

fbackup

How do you make a copy of a fbackup tape?
It is not a problem, but a learning experience.
6 REPLIES
Mike Gilmore IS T
Occasional Visitor

Re: fbackup

fbackup uses a proprietary format chock full of tape EOF markers that the docs say can't be copied with dd.
Tape machines (try cybernetics) come with a copy mode for their daul models that may do what you need. I would contact them. They currently sell AIT but have done exabyte in the past.
making computing safe for albertsons
Kevin Ernst
Regular Advisor

Re: fbackup

Read Bill Hassell's reply to this post on the Dutchworks hpux-admin mailing list (I hope this link works):

http://www.dutchworks.nl/htbin/hpsysadmin?h=3&dn=20027&q=copy%20tape%20fbackup&fh

In summary: fbackup creates archives on tape using a variable, rather than a fixed, record size. dd and similar utilities can't deal with this. Bill suggests using an ancient (circa 1986, judging by the man page), revered utility called 'copytape,' which will copy tape archives created using fbackup in spite of their variable record size.

I think you may find that the link to the copytape tarball that Bill mentions (found at Unix Guru Universe: http://www.ugu.com ) is broken. Try searching for 'copytape.tar.Z' or 'copytape.tar.gz' at http://ftpsearch.lycos.com . (As far as I can tell, the 'compressed' and 'gzipped' archives contain the exact same files.) They're out there somewhere.

I have successfully compiled copytape on a 10.20 system (nothin' to it), but I haven't attempting to duplicate any tapes yet. Judging by some of the other posts to hpux-admin (and Bill's recommendation), it should work fine for single-tape backup sets, but you may have problems duplicating multi-volume sets. Maybe Bill will pick up on this thread and clarify?


For future reference (in case anyone's interested), you can search the hpux-admin archives at the following URL:

http://www.dutchworks.nl/htbin/hpsysadmin
Kevin Ernst
Regular Advisor

Re: fbackup

My boss has been wondering whether you could pipe the output of an 'frestore' which reads from a backup tape in one drive into an 'fbackup' which writes to a second drive. This would (in theory) recreate the original backup set on the second tape device.

I haven't actually done the experiment yet, but does anyone care to speculate on this possibility?
Kevin Ernst
Regular Advisor

Re: fbackup

I guess that would hinge upon fbackup's having an option similar to tar's '-f -' option and gzip's '-c' option (read from/write to stdout). Suppose I'll check into it soon, now that my interest has been piqued a bit.
Bill Hassell
Honored Contributor

Re: fbackup

copytape should work fine. For some reason, it seems that Unix originators simply ignored tape devices in the way that mini's and mainframes used them for more than 2 decades. The only thing necessary to copy a tape is the ability to read each record (with a buffer larger than the largest possible record) and ask the tape driver what was just read as in: normal record and the length, end-of-file marker, end-of-tape marker, and so on.

The dd program is called dd because it primarily is used for disk-to-disk copies (despite the man page's comments about tapes). dd might be convinced to read random record sizes and actually duplicate them on output..I haven't been successful.

As far as copying a multi-volume tape, each continuation volume is just another tape so copying the tape should be easy with copytape. But one precaution: Tape errors on the destination may be handled by erasing over the bad area and continuing on--which will make the destination tape smaller in total output size. So it is possible that the source may not fit on the destination.

Which brings us back to the frecover piped to fbackup solution. Since fbackup will accept stdin with -f -, then it should work, even for a multivolume copy.


Bill Hassell, sysadmin
Paul van der Mee
Occasional Visitor

Re: fbackup

Hi

I've just had the same problem (i wanted to copy an fbackup tape made on a HP-UX 11 machine).

It turned out that copytape does the job.

regards

Paul