Re: How Does this work in Detail: Archiving the Standby Redo Log on the Standby Database

From: joel garry <joel-garry_at_home.com>
Date: Thu, 22 Oct 2009 17:17:03 -0700 (PDT)
Message-ID: <4826c007-ca81-4ac8-8b52-fcdda94a4b02_at_j9g2000prh.googlegroups.com>

On Oct 22, 4:19 pm, cfoughty <cfoug..._at_gmail.com> wrote:
> On Oct 22, 4:06 pm, joel garry <joel-ga..._at_home.com> wrote:
>
>
>
> > On Oct 22, 12:23 pm, cfoughty <cfoug..._at_gmail.com> wrote:
>
> > > On Oct 22, 12:21 pm, cfoughty <cfoug..._at_gmail.com> wrote:
>
> > > > This is mainly just for my interest.
>
> > > >  The documentation says the following:
>
> > > > A log switch on the primary database triggers a log switch on the
> > > > standby database, causing ARCn processes on the standby database to
> > > > archive the standby redo log files to archived redo log files on the
> > > > standby database.
>
> > > > So what process on the primary sends the message to what process on
> > > > the standby telling the ARCH on the standby server to archive the
> > > > current standby redo log?
>
> > > > Does the ARCH process on the primary send a message to the RFS process
> > > > on the standby server, and then the RFS process sends a message to the
> > > > ARCH process on the standby server telling the standby server ARCH to
> > > > archive the current standby redo log?
>
> > > > OR
>
> > > > Does the ARCH process on the primary send a message to the ARCH
> > > > process on the standby server telling the standby ARCH to archive the
> > > > current standby redo log?
>
> > > > OR
>
> > > > Some other method to tell the ARCH process on the standby server to
> > > > archive the current standby redo log?
>
> > > > I just want to know how it works.
>
> > It depends:  http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/log_tr...
>
> > Look at table 5-2 and the pretty pictures throughout.
>
> > > > Thanks,
>
> > > > Cy Foughty
>
> > > I'm running 10gR2
>
> > jg
> > --
> > _at_home.com is bogus.http://www.flickr.com/photos/scobleizer/29119056/
>
> That's a high level view. I want to know down at the process level.

Are log writer and archivers not processes? Not sure really what you are asking for. People at conferences have published papers about it, but the ones I've seen have just been a rehashing of the docs, though usually more linearly organized. It depends which way you are configured, and can change from one way to another under certain circumstances.

In one mode:

"Archiving happens when a log switch occurs on the primary database:

    *

      On the primary database, after the ARC0 process successfully archives the local online redo log to the local destination (LOG_ARCHIVE_DEST_1), the ARC1 process transmits redo from the local archived redo log files (instead of the online redo log files) to the remote standby destination (LOG_ARCHIVE_DEST_2).

    *

      On the remote destination, the remote file server process (RFS) will, in turn, write the redo data to an archived redo log file from a standby redo log file. Log apply services use Redo Apply (MRP processFoot 1 ) or SQL Apply (LSP processFoot 2 ) to apply the redo to the standby database.
"

To me, anyways, figure 5-3 is much clearer than that. How low do you want to go?

jg

--
_at_home.com is bogus.
http://img.geocaching.com/user/435c10dc-60ba-45a6-917b-1cd00cc70ef0.jpg

Received on Thu Oct 22 2009 - 19:17:03 CDT