topic Re: fbackup spanning multiple tapes in Operating System - HP-UX

fbackup spanning multiple tapes

Nivesh Patnaik — Tue, 29 Jan 2002 18:28:42 GMT

Hello,
I have an 9000/803 workstation running HP-UX 10.20 with almost 8 GB
of data that I must back up on DDS 4GB tapes.

Right now I use the following commmand on the command line to
get a full backup -->
/usr/sam/lbin/br_backup DAT FULL Y /dev/rmt/0m /etc/sam/br/fullbackup root Y 1 N

I get the following messages, the last one asking me to insert another
tape for the remaining data to be backed up -->
br_backup: Invoking fbackup. See /var/sam/log/br_log for details.
fbackup(1004): session begins on Tue Jan 29 11:12:51 2002
fbackup(3203): volume 1 has been used 79 time(s)
fbackup(3024): writing volume 1 to the output file /dev/rmt/0m
fbackup(3003): normal EOT
fbackup(3316): enter 'yes' when volume 2 is ready on /dev/rmt/0m,
or 'no' to discontinue:

I has some questions in that regard.
1) What if I were to use /dev/rmt/0mnb instead of /dev/rmt/0m? Would that cause
a problem with backups spanning multiple tapes?
2) If I were to put the FULL backup command in a crontab, what would
happen at the point where fbackup expects a 'yes' or 'no' for the
second volume? Does the behaviour of fbackup change such that if I
used it in a crontab, I would simply have to change the tape and
the backup would automatically resume (since I wouldn't have a
terminal on which to respond to fbackup's question)? If this method works, should
I be using 'rewind' or 'norewind' for the tape device?

I have very little experience with backups, so any help would be
fantastic.

Thanks.
-Nives

Re: fbackup spanning multiple tapes

James R. Ferguson — Tue, 29 Jan 2002 18:38:15 GMT

Hi:

'fbackup' handles multiple tapes. You *do* want to use the rewind tape device; be prepared to respond "yes" or "no" when prompted; *and* put a second, third, etc. tape into the tape drive.

The principal issue therefore is the interactive response (yes|no). If you have initiated the backup from a cron job (and this includes SAM's scheduling mechanism), then you need to have a 'chgvol' script in place to assist in the tape volume change.

You have to set things up yourself. Attached is a document from the Technical Knowledge Base (#KBRC00001392) which describes the procedure for SAM-based backups. It should be easy to adopt for your needs.

Regards!

...JRF...

Re: fbackup spanning multiple tapes

Sanjay_6 — Tue, 29 Jan 2002 18:40:55 GMT

Hi Nivesh,

If you use a norewind device, you'll have to rewind the tape before restoring data from it, or before writing to the tape.

If you put the fbackup script in cron, you will not know when to replace the tape. The cron job will exit when it asks you to replace the tape. how to plan on letting the cron know, you have replaced the tape. If you have two drives, you can use the fbackup command to use the 2nd drive after it has finished writing the first.

Hope this helps.

Regds

Re: fbackup spanning multiple tapes

Thierry Poels_1 — Tue, 29 Jan 2002 18:44:37 GMT

Hi,

1) the device chosed does not really matter, fbackup will ALWAYS rewind the tape even if you use a no-rewind device.

2) fbackup only waits for user input if it is executed interactively, NOT in batch (e.g. cron).

So you could leave out some unimportant stuff for the include list, or you can use a chgvol script, that will really wait for a next tape.
See this thread:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x0fdcd211e18ad5118ff10090279cd0f9,00.html

good luck,
Thierry.

Re: fbackup spanning multiple tapes

harry d brown jr — Tue, 29 Jan 2002 19:29:10 GMT

Nives,

If you put a new tape in your tape drive every day, and you use the /dev/rmt/0mnb device, then it won't make much of a difference. Using the device /dev/rmt/0m is more than adequate for fbackup.

read:

Naming convention for systems installed with long file names. c#t#d# derives from ioscan output: c# is the card instance number for the ext_bus class of interface card to which the tape drive is attached, t# is the SCSI address, d# is the device number. BEST represents the operational capabilities likely to be required, including the highest density/format and data compression, if supported by the device. [b|n|nb] designates tape positioning: b is Berkeley-style; that is, after file close, the tape is not repositioned in any way. If b is not designated, AT&T-style tape closing occurs; that is the tape might be positioned after the end-of-file (EOF) point. n designates no rewind.

from:
http://docs.hp.com/hpux/onlinedocs/B2355-90053/B2355-90053_top.html

live free or die
harry

Re: fbackup spanning multiple tapes

Bill Hassell — Wed, 30 Jan 2002 03:37:20 GMT

When cron runs, there is usually no one there to answer the question. cron is not associated with any terminal so even if you came in later to replace the tape, there will be no place for you to answer the question so fbackup terminates. fbackup will never overwrite the previous tape as it writes a special header on every tape volume.

If you cannot get a tape loader, you'll have to change the backup scope to split the backup onto two tapes and use two separate cron jobs on different days to perform the total backup.

Sometimes, you can get almost 8Gb onto a 4Gb tape but you must use a config file to set the fbackup parameters from 1/2 reel tape to 4mm DDS tapes. See the example at:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xf793663ce855d511abcd0090277a778c,00.html