There are two servers between which DataGuard is setup. The replication
happens from server-1 to server-2. server-1 is currently serving and
server-2 acts as a standby. I would like to know the following related
to this setup:
1) server-2 is in standby mode. Can server-2 start serving immediately
in case if server-1 goes out-of-service due to some problems? If not
immediate, how much time it will typically take for take-over?

2) Assume server-2 has started serving and hence it is in 'Active'
mode. Is it possible to do reverse replication of DB changes from
server-2 to server-1(similar to the replication from server-1 to
server-2 before takeover happened)?

qazmlp1209@rediffmail.com wrote:
> There are two servers between which DataGuard is setup. The replication
> happens from server-1 to server-2. server-1 is currently serving and
> server-2 acts as a standby. I would like to know the following related
> to this setup:
> 1) server-2 is in standby mode. Can server-2 start serving immediately
> in case if server-1 goes out-of-service due to some problems? If not
> immediate, how much time it will typically take for take-over?
>
> 2) Assume server-2 has started serving and hence it is in 'Active'
> mode. Is it possible to do reverse replication of DB changes from
> server-2 to server-1(similar to the replication from server-1 to
> server-2 before takeover happened)?
>

1) You provide us with the answer, as you have tested your scenario.
You *did*, now did you not?
And no - there is some overhead, for starters, server 2 has to
become aware of the fact server 1 died.

2) Yes - and you actually *want* that. Repair server 1 and make it
the backup of #2 - in case #2 gets hit by the same problems as #1
did suffer from...

Again - you tested that scenario, didn't you (tongue in cheek!)
--
Regards,
Frank van Bortel

qazmlp1209@rediffmail.com wrote:
> There are two servers between which DataGuard is setup. The replication
> happens from server-1 to server-2. server-1 is currently serving and
> server-2 acts as a standby. I would like to know the following related
> to this setup:
> 1) server-2 is in standby mode. Can server-2 start serving immediately
> in case if server-1 goes out-of-service due to some problems? If not
> immediate, how much time it will typically take for take-over?
>
> 2) Assume server-2 has started serving and hence it is in 'Active'
> mode. Is it possible to do reverse replication of DB changes from
> server-2 to server-1(similar to the replication from server-1 to
> server-2 before takeover happened)?

Version of Oracle database?
Logical or physical?
Have you set up TAF (transparent application failover)?
--
Daniel A. Morgan
http://www.psoug.org
damorgan@x.washington.edu
(replace x with u to respond)

qazmlp1209@rediffmail.com wrote:
> There are two servers between which DataGuard is setup. The replication
> happens from server-1 to server-2. server-1 is currently serving and
> server-2 acts as a standby. I would like to know the following related
> to this setup:
> 1) server-2 is in standby mode. Can server-2 start serving immediately
> in case if server-1 goes out-of-service due to some problems? If not
> immediate, how much time it will typically take for take-over?

No, it is not immediate. How long this opearation will take is
dependent on your setup. According to my experiencies it can take few
minutes.
>
> 2) Assume server-2 has started serving and hence it is in 'Active'
> mode. Is it possible to do reverse replication of DB changes from
> server-2 to server-1(similar to the replication from server-1 to
> server-2 before takeover happened)?

Everything is in Data Guard documentation. After failover you have to
create a new standby database on server-1 from formerly standby now
primary database (database on server-2) backup and after
synchronization of these two databases you can perform a switchover
which will replace primary and standby positions (that means server-1
is primary and server-2 standby again).

--
Dusan Bolek

DA Morgan wrote:
> qazmlp1209@rediffmail.com wrote:
> > There are two servers between which DataGuard is setup. The replication
> > happens from server-1 to server-2. server-1 is currently serving and
> > server-2 acts as a standby. I would like to know the following related
> > to this setup:
> > 1) server-2 is in standby mode. Can server-2 start serving immediately
> > in case if server-1 goes out-of-service due to some problems? If not
> > immediate, how much time it will typically take for take-over?
> >
> > 2) Assume server-2 has started serving and hence it is in 'Active'
> > mode. Is it possible to do reverse replication of DB changes from
> > server-2 to server-1(similar to the replication from server-1 to
> > server-2 before takeover happened)?
>
> Version of Oracle database?
Oracle 9i. Is this different in Oracle 10g?

> Logical or physical?
Physical.

> Have you set up TAF (transparent application failover)?
No. The servers server-1 and server-2 are located few kilometers apart.
Is TAF supposed to be used, for such a setup also? As I am aware, TAF
is used mainly among 2 cluster nodes, which are closer & connected by
'Cluster interconnect'.