Re: One primary with two physical standbys exhibiting different behavior with regard to lag

It's not RAC. I checked the thread#. For the standby redo, it's thread 0 as you mentioned. I read your article. Very nice, thank you.

Sandy

On Thu, Jan 3, 2019 at 2:34 PM Neil Chandler <neil_chandler_at_hotmail.com> wrote:

> Sandy,
>
> Have you checked the Standby Redo logs? There's a slight (annoying) change
> in Oracle 12.1 onwards which means that Standby Redo logs get created with
> Thread 0 instead of Thread 1 by default (for a single instance database).
> Redo can only use Standby Redo when the threads are the same. If this is
> RAC you need Standby Redo for each thread - and you must have 1 more
> Standby Redo than Online Redo for each thread.
>
> By coincidence, I wrote a blog post about this 10 minutes ago.
>
> https://chandlerdba.com/2019/01/03/data-guard-unexpected-lag/
>
> regards
>
> Neil Chandler
> Database Guy. Knows Things.
>
> ------------------------------
> *From:* oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> on
> behalf of Sandra Becker <sbecker6925_at_gmail.com>
> *Sent:* 03 January 2019 20:29
> *To:* oracle-l
> *Subject:* One primary with two physical standbys exhibiting different
> behavior with regard to lag
>
> Oracle 12.1.0.2
> RHEL7
>
> To begin with, I have not worked much at all with standby databases, so my
> knowledge is somewhat lacking.
>
> For business reasons, we have a primary database with two physical
> standbys. Everything is configured in dgmgrl and enabled. Monitoring with
> EM13c is reporting the lag times, so all looks good for basic setup and
> monitoring. We seem to have significant lag at times on one of the
> standbys, as much as 20 minutes. When looking at v$managed_standby, we see
> the status as "WAIT_FOR_LOG". The other standby never seems to be more
> that a few seconds behind, if at all, and the status is "APPLYING_LOG".
>
> Is this normal? I've been researching, but haven't found an answer yet.
> I didn't create or start the standby databases, so I don't have any idea
> what was actually done that could be causing this behavior. Any
> suggestions would be appreciated.
>
> Thank you,
>
> --
> Sandy B.
>
>

-- 
Sandy B.

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