IDS Forum

Re: Onbar Backup

Posted By: Martin Fuerderer
Date: Tuesday, 27 May 2014, at 5:37 a.m.

In Response To: Re: Onbar Backup (Art Kagel)

Hi,

whatever in the end you choose to do, please test it thoroughly,
not just by doing some backups, but also by restoring them !

[ I still seem to have in mind (after several years), that ON-Bar
may need logical log content in order to restore certain types
of backups.

This was/is mainly the case when the ON-Bar backup is not a
whole system backup, because in this case, each dbspace
gets backed up with its own, individual archive checkpoint.
A system restored from such a backup is not consistent after
the physical restore part, because of the individual archive
checkpoints of the different dbspaces. In this case, logical log
records are needed, to make the system logically consistent
to a single reference point (i.e. archive checkpoint). The
restore needs to retrieve these logical log records from the
logical log backups. If logical logs were not backed up, then
the restore will not be able to make the system logically
consistent.

The concept of a "whole system backup" was introduced
relatively late for ON-Bar (whereas it always was and is the
only mode for ontape). With a whole system backup, there
is a) only a single archive checkpoint for all dbspaces and
b) the logical log records needed later during restore to
synchronize everything to this single archive checkpoint
are contained within the backup. In this case, no logical
log backup is needed for a restore.

At least, this is what I recall. :)
]

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

Read about the Informix Warehouse Accelerator:
http://tinyurl.com/the-iwa-blog

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From: "Art Kagel" <art.kagel@gmail.com>
To: ids@iiug.org,
Date: 05/27/2014 01:10
Subject: Re: Onbar Backup [33104]
Sent by: ids-bounces@iiug.org

YES! Here's the deal. If you can afford to lose all transactions that
committed between the archives then you don't need to back up logical
logs.
Most sites cannot afford to lose that data.

Art S. Kagel

Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on the IIUG or any other organization with which I sm
associated either explicitely or implicitely not on individuals affiliated

with those organizations.

On May 26, 2014 6:57 PM, "Jorge" <jorgervt@gmail.com> wrote:

> I have configured only an onbar backup level 0 every night. When I will
> need a restore I will do a level 0 restore.
> In this case do I need to backup the logical logs or is not necesary?
>
> Thanks in advance.
>
> Enviado desde mi iPhone
>
> El 26/05/2014, a las 14:56, "Jack Parker" <jack.parker4@verizon.net>
> escribió:
>
> > Only if you want to roll forward from the level 0. So logs BEFORE the
=
> > level 0 aren=92t much use, but the ones between your backups are.
> >
> > j.
> >
> > On May 26, 2014, at 5:48 PM, Jorge <jorgervt@gmail.com> wrote:
> >
> >> Hi,=20
> >> =20
> >> If I always do a level 0 backup using onbar, Do I need to backup the
=
> > logical=20
> >> logs to do a restore?=20
> >> =20
> >> Thanks in advance.=20
> >> =20
> >> Enviado desde mi iPhone=20
> >> =20
> >> =20
> >> =
> >
>
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=

> > *****=20
> >> Forum Note: Use "Reply" to post a response in the discussion
forum.=20=
> >
> >> =20
> >
> >
> >
>
>
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> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
>
>
>
>
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> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--14dae947322ba0451904fa55ad68

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Forum Note: Use "Reply" to post a response in the discussion forum.

Messages In This Thread

• Onbar Backup
  Jorge -- Monday, 26 May 2014, at 5:48 p.m.
  • Re: Onbar Backup
    Jack Parker -- Monday, 26 May 2014, at 5:56 p.m.
    • Re: Onbar Backup
      Jorge -- Monday, 26 May 2014, at 6:57 p.m.
      • Re: Onbar Backup
        Art Kagel -- Monday, 26 May 2014, at 7:10 p.m.
        • Re: Onbar Backup
          Martin Fuerderer -- Tuesday, 27 May 2014, at 5:37 a.m.
          • Re: Onbar Backup
            JON RITSON -- Tuesday, 27 May 2014, at 6:51 a.m.
            • Re: Onbar Backup
              david@smooth1.co.uk -- Tuesday, 27 May 2014, at 5:26 p.m.
          • Re: Onbar Backup
            Jorge -- Tuesday, 27 May 2014, at 2:36 p.m.
            • Re: Onbar Backup
              Art Kagel -- Tuesday, 27 May 2014, at 2:44 p.m.
      • Re: Onbar Backup
        Jack Parker -- Monday, 26 May 2014, at 7:10 p.m.

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