IDS Forum

Re: Onbar and LTAPEDEV

Posted By: Martin Fuerderer
Date: Wednesday, 19 March 2008, at 10:45 a.m.

In Response To: Re: Onbar and LTAPEDEV (MIKE MAGIE)

Hi,

no!

"onbar -b -L 0" is doing a parallel backup of dbspaces.
Parallel here means (among other things) that each dbspace
is backed up with its own consistency reference point (aka
archive checkpoint). And because of that restore of such
a backup will need logical logs to "compensate" all those
dspaces's consistency points to reach overall consistency for
all dbspaces together.
Without logical logs backed up you will not be able to
successfully restore such backups. And this is why (in newer
versions at least) onbar will not let you do such a backup when
LTAPEDEV is set to /dev/null.

If you want to do a useful (i.e. restorable) backup while not
backing up logical logs, then you need to do a so called
"whole system backup". This is denoted by a "-w" in the
onbar command line, like:

"onbar -b -w [ -L 0 ]"

Such a backup can then be restored without logical logs and
still bring the instance to a consistent state.

In newer versions (since 11.10, I believe), this whole system
backup can also be done in parallel, but still with one
(i.e. the same) archive checkpoint for all dbspaces. Therefore
no logs are needed for restore of this.

In older versions, a whole system backup can be done
serially only (onbar syntax is the same). Here it is very much
like a normal backup with ontape (which is always serial and
by default "whole system").

Regards,
Martin
--
Martin Fuerderer
IBM Informix Development Munich, Germany
Information Management

IBM Deutschland Entwicklung GmbH
Chairman of the Supervisory Board: Martin Jetter
Board of Management: Herbert Kircher
Corporate Seat: Boeblingen, Germany
Reg.-Gericht: Amtsgericht Stuttgart, HRB 243294

ids-bounces@iiug.org wrote on 19.03.2008 15:08:51:

> Art -
>
> Thanks for the response and the suggestions. I have a good understanding
of
> the role that logical logs play in archive/restore scenarios, as well as
the
> importance of backing up logs in most cases. In our case we do not need
to
> backup logs. Based on this...
>
> If LTAPEDEV is set to /dev/null will onbar -b -L 0 write the log(s) that
are
> current during the archive process to the archive media?
>
> Thanks!
>
> Mike Magie
>
>
>
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Messages In This Thread

• Onbar and LTAPEDEV
  MIKE MAGIE -- Tuesday, 18 March 2008, at 12:26 p.m.
  • Re: Onbar and LTAPEDEV
    Gustavo Castro -- Tuesday, 18 March 2008, at 1:10 p.m.
    • Re: Onbar and LTAPEDEV
      MIKE MAGIE -- Tuesday, 18 March 2008, at 3:13 p.m.
      • Re: Onbar and LTAPEDEV
        Art S. Kagel (Oninit) -- Tuesday, 18 March 2008, at 5:06 p.m.
        • Re: Onbar and LTAPEDEV
          MIKE MAGIE -- Wednesday, 19 March 2008, at 10:08 a.m.
          • Re: Onbar and LTAPEDEV
            Paul Watson -- Wednesday, 19 March 2008, at 10:15 a.m.
            • Re: Onbar and LTAPEDEV
              MIKE MAGIE -- Wednesday, 19 March 2008, at 10:27 a.m.
              • Re: Onbar and LTAPEDEV
                Paul Watson -- Wednesday, 19 March 2008, at 10:31 a.m.
          • Re: Onbar and LTAPEDEV
            John Miller iii -- Wednesday, 19 March 2008, at 10:29 a.m.
          • Re: Onbar and LTAPEDEV
            Martin Fuerderer -- Wednesday, 19 March 2008, at 10:45 a.m.
          • Re: Onbar and LTAPEDEV
            Art S. Kagel (Oninit) -- Wednesday, 19 March 2008, at 11:43 a.m.
            • Re: Onbar and LTAPEDEV
              MIKE MAGIE -- Wednesday, 19 March 2008, at 12:10 p.m.
              • Re: Onbar and LTAPEDEV
                Martin Fuerderer -- Wednesday, 19 March 2008, at 12:57 p.m.
                • Re: Onbar and LTAPEDEV
                  DAVE GRIFFEN -- Wednesday, 19 March 2008, at 4:32 p.m.

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