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Re: Oracle9i Standby Database Question

From: Pete Sharman <peter.sharman_at_oracle.com>
Date: Thu, 31 Jan 2002 08:46:09 -0800
Message-ID: <wve68.9$8X1.234@inet-nntp1.oracle.com>


Sorry for the delay in responding. I've been out of the office for a few days and use my desktop to access News.

I'm not 100% clear on what you mean. I can't see any reason for the primary server to crash because the CPU is overloaded, unless you have a bug at the OS level to make it crash. In any case, graceful switchover can only be done if you have access to the primary and the standby, so if the primary crashes for any reason, no you can do a graceful switchover. How long failover takes is one of those questions to which the answer is "it depends". It's a manual operation (thankfully - I'd hate to think of the ramifications of automatic failover - ugh!), so it depends on how long it takes you to determine the failure has occurred, how many redo logs have not been applied to the standby yet and so on.

--
HTH.  Additions and corrections welcome.

Pete
Author of "Oracle8i: Architecture and Administration Exam Cram"

"Controlling developers is like herding cats."
Kevin Loney, Oracle DBA Handbook

"Oh no, it's not.  It's much harder than that!"
Bruce Pihlamae, long-term Oracle DBA

"K. C." <the_ada_at_hotmail.com> wrote in message
news:be879ba7.0201271037.20657bf_at_posting.google.com...

> Hi Pete,
>
> Would I be able to do a switchover if the primary server crashes
> because the CPU is overloaded? How long does it usually take for a
> primary database to failover to a standby database?
>
> Thanks,
> KC
>
> "Pete Sharman" <peter.sharman_at_oracle.com> wrote in message
news:<tjg48.9$If3.139_at_inet-nntp1.oracle.com>...
> > Depends on whether this was a graceful shutdown of the primary or not.
If
> > it was not, then what you've done is a failover. The database that
started
> > as the primary cannot be used as a new standby database. This must be
> > completely rebuilt using backups and logs from the new primary (old
standby)
> > database. The normal failover process that forces database recreation
occurs
> > when all of the available archive logs are applied to the standby
database,
> > and the standby is opened as the primary using the following SQL
command:
> >
> > alter database activate standby database;
> >
> > When this command is executed, a resetlogs operation is performed
> > automatically on the standby and the new logs cannot be applied to the
old
> > primary.
> >
> > If however, you've done a switchover (new in 9i) then you're OK.
> > Switchover is possible only if the standby and its primary database can
be
> > brought to the same point in time. The prerequisites of initiating
> > switchover include:
> >
> > .1. The primary database has been shut down in an orderly fashion; that
is,
> > SHUTDOWN NORMAL, SHUTDOWN TRANSACTIONAL or SHUTDOWN IMMEDIATE.
> > .2. All archive logs required to bring the standby to the primary's
point
> > in time are available.
> > .3. The primary database's online redo logs are available and intact,
as
> > are its data files and control files.
> >
> > --
> > HTH. Additions and corrections welcome.
> >
> > Pete
> > Author of "Oracle8i: Architecture and Administration Exam Cram"
> >
> > "Controlling developers is like herding cats."
> > Kevin Loney, Oracle DBA Handbook
> >
> > "Oh no, it's not. It's much harder than that!"
> > Bruce Pihlamae, long-term Oracle DBA
> >
> > "K. C." <the_ada_at_hotmail.com> wrote in message
> > news:be879ba7.0201241847.545913fb_at_posting.google.com...
> > > I have a question regarding Oracle9i Standby Database on Unix. Say I
> > > have a primary database running on Server A and a standby database
> > > running on Server B. For some reason, Server A goes down and the
> > > standby database is activated. What is the quickest way to switch the
> > > databases so that Server A (assuming whatever problem it had was
> > > fixed) becomes the primary again?
> > >
> > > Thanks in advance.
> > >
> > > KC
Received on Thu Jan 31 2002 - 10:46:09 CST

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