fbackup using /dev/rmt/0mn

[Philip J. Priest_1]

Im in a SAN enviro, with st_san_safe enabled. Im using fbackup to do "full" backups.

Would there be issues in using "no-rewind-on-close" for fbackup? The man page says not to use "no-rewind" for fbackup.

thanks!
Phil

[Patrick Wallek]

Using the no-rewind devcie really wouldn't do you any good.

fbackup ALWAYS rewinds the tape before the backup starts and, I think, when it finishes.

You are better off just using /dev/rmt/0m.

If you are thinking about trying to put more than 1 fbackup on a tape, banish that thought right now. You will not be able to do it.

[Philip J. Priest_1]

Since i have st_san_safe set to 1, im not able to use /dev/rmt/0m for fbackup.

Can i still continue to use /dev/rmt/0mn and be able to frecover off these tapes?

[Deoncia Grayson_1]

yes you should be able to continue that device and frecover should work just fine.

[Bill Hassell · Accepted solution]

fbackup manages tape motion completely within the program, not like tar or cpio where things like rewind are not automatic. Like all commercial quality backup software, the tape is rewound before use, read to determine if this is a previous fbackup tape and rewinds (always) at the end of a backup. I'm not sure why the man page has the no-rewind option--fbackup works fine with 0m, 0mn, 0mnb.

[Xaviea Bell]

Because of this st_san_safe we use the 0mn device file and it works fine, the frustrating part is if you are doing multiple restores using frecover, you must eject the tape in order to get it to rewind to restore from that tape.

[Bill Hassell]

I am very curious about 'multiple restores' requiring tape eject. frecover can restore hundreds of random files and directories in a single pass. The only possibility is that your backup is not the 'supported and reliable' method: fbackup ..options.. -f /dev/rmt/0mn but instead -f has been sent to a pipe (-f -) which is then sent to the tape so that multiple fbackups can be stored on a single tape. Multiple backups on the same tape are extremely dangerous and you lose all of the content integrity and high-speed restore features built into fbackup. All commercial backup programs will refuse to store multiple backups on the same tape for the same reasons.

[Xaviea Bell]

When we are doing "multiple restores", I mean that by as we do database clones, certain files need to go to different filesystems and my understanding is taht while doing frecover you cannot specify more than one non-root directory to restore in. Our systems are a little strange in that the file systems are not set up the same way across the board.

[Bill Hassell]

Okay, I understand now. Have you tried using mt to rewind and get a status on the tape drive?

mt -f /dev/rmt/0mnb rewind
mt -f /dev/rmt/0mnb status

Note the use of the Berkeley device file (letter b). This is required for all mt commands so no unwanted motion occurs after mt has completed it's task. See man mt

[Xaviea Bell]

Thanks Bill! I tried that that command but with just the AT&T files. That did a rewind on the tape. Sweet!