Question abt RAC-TAF

Do not inplement RAC just for TAF.

TAF is a marketing gimmick which does not work most of the time. Its good only to be used with SQL*PLUS to show demos. Tell me where do u use sqlplus ? Only the DBA and the develpoment team does that and not the end user. Also only select statement works with TAF and not inserts, updates or deletes. Also the sql select TAF is just a replay of the query fired (information is stored about the number of rows that have been thrown to the client and starts throwing after that row). TAF can be implemented on single node databases.

You can use TAF not for Application faliover but for session failovers(to some extent) and login failovers.

You can use the TAF along with OCI to inform you that one of the RAC node is down and you need to restart your application transaction again. Use the OCI call back function to do this.

When one node goes down this error will be thrown "ORA-25402: transaction must roll back". You can then use the OCITransRollback to rollback and restart your trabsaction again.

Remember RACs main purpose is not High Availibility. Its main purpose is scalability and load balancing. Yes High Availibility in the sense that nodes are available but not if the clustered disk system goes down (datafiles).

HTH

Quote:

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Originally posted by adewri
Do not inplement RAC just for TAF.

TAF is a marketing gimmick which does not work most of the time. Its good only to be used with SQL*PLUS to show demos. Tell me where do u use sqlplus ? Only the DBA and the develpoment team does that and not the end user. Also only select statement works with TAF and not inserts, updates or deletes. Also the sql select TAF is just a replay of the query fired (information is stored about the number of rows that have been thrown to the client and starts throwing after that row). TAF can be implemented on single node databases.

You can use TAF not for Application faliover but for session failovers(to some extent) and login failovers.
HTH

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I agree with you here. Even TAF with sql*plus is sketchy. I did OPS and attempted TAF with a HA 311 phone system. I was able to get TAF to work for query failover sometimes and sometimes not in the development stages. As part of the Oracle Contract , Oracle corp sent in a HA specialist to audit my work. He was left scratching is head over why TAF worked sometimes and sometimes not and we was quite throughough in the review of my config.

Quote:

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Originally posted by stmontgo
I agree with you here. Even TAF with sql*plus is sketchy. I did OPS and attempted TAF with a HA 311 phone system. I was able to get TAF to work for query failover sometimes and sometimes not in the development stages. As part of the Oracle Contract , Oracle corp sent in a HA specialist to audit my work. He was left scratching is head over why TAF worked sometimes and sometimes not and we was quite throughough in the review of my config.

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I have almost the same experience.

However, Oracle promised some years ago that TAF will work outside SQL*Plus. Has this been achieved?

Quote:

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Originally posted by adewri
Do not inplement RAC just for TAF.

TAF is a marketing gimmick which does not work most of the time. Its good only to be used with SQL*PLUS to show demos. Tell me where do u use sqlplus ? Only the DBA and the develpoment team does that and not the end user. Also only select statement works with TAF and not inserts, updates or deletes. Also the sql select TAF is just a replay of the query fired (information is stored about the number of rows that have been thrown to the client and starts throwing after that row). TAF can be implemented on single node databases.

You can use TAF not for Application faliover but for session failovers(to some extent) and login failovers.

You can use the TAF along with OCI to inform you that one of the RAC node is down and you need to restart your application transaction again. Use the OCI call back function to do this.

When one node goes down this error will be thrown "ORA-25402:
transaction must roll back". You can then use the OCITransRollback to rollback and restart your trabsaction again.

Remember RACs main purpose is not High Availibility. Its main purpose is scalability and load balancing. Yes High Availibility in the sense that nodes are available but not if the clustered disk system goes down (datafiles).

HTH

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well said..thats perhaphs the reason why DBA's dont make good marketing folks..

I always thought RAC's main purpose was high availability though coz in 10g RAC lotta of emphasis was placed on avalability like ability to do rolling upgrades ..scalability and loadbalancing was always a icing that you got from RAC.

I have been through RAC classes and the general response from the public or atleast 90% of the DBA's was well this is not what i was looking for DataGaurd or Standby database is really what i would be more interested in.

Anyways different folks and different opinions

regards
Hrishy


regards
Hrishy

Quote:

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Originally posted by hrishy

I always thought RAC's main purpose was high availability though coz in 10g RAC lotta of emphasis was placed on avalability like ability to do rolling upgrades ..

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You can patch a 10g RAC while the DB is up and running in exclusive mode but I don't think this is very attractive as a feature. People always get the dowtime for maintenance..