Re: RAC or Oracle Fail Safe

Hi!

RAC - One database, two (or more) instances servicing it concurrently. If one node crashes, second one starts recovering, your uncommitted transactions and session state variables (package variables) on failed instance are lost.

FailSafe - One database, one instance servicing it at any time, in event of failure you can start up instance on another node that will mount, recover and open the database.

With RAC you can have some kind of transparent failover which is able to reexecute your queries on survived instance, but AFAIK for uncommitted transaction survivability your app has to be coded to support it. Also, with RAC you may scale your system up to support more users in some cases.

RAC is additional $20k per CPU, FailSafe comes with EE, I believe.

Tanel.

• Original Message ----- From: "Hussain Ahmed Qadri" <hussain_at_skm.org.pk> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, July 16, 2003 7:44 PM Subject: RAC or Oracle Fail Safe

> Hello all,
>
> We have setup a Microsoft Cluster Server (MSCS) cluster, with two nodes,
using W2K, and now are in the process of deploying Oracle 9i on it. For the purpose of high availability (HA), we are deliberating on setting up either RAC or Oracle Fail Safe. The confusion is over the fact that if we get HA with oracle Fail Safe, i.e. if one node is down due to any problem, then the other takes over, then can we do without RAC?
> Which of these two is more transparent to the user, i.e. which will take
less time to shift the load from one node (server) to the other node?
> Can any one explain the benefits of using RAC over Oracle Fail Safe, or
vice versa.
>
> Regards,
>
> Hussain
>
> DBA SKMCH&RC
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Hussain Ahmed Qadri
> INET: hussain_at_skm.org.pk
>
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Received on Wed Jul 16 2003 - 11:44:15 CDT