Re: Trying to wrap my head around TAF
Date: Mon, 22 Jun 2009 08:10:20 +0300
About point number 1:
You do not see this configuration because you do not want the application to fail over AUTOMATICALLY to the stand by server. Most places use stand by for the second site and it is activated only as the last resource.
Charles Schultz wrote:
> [Warning: High acronym content]
> So I have been reading the online documentation and giving myself a
> headache. =) Interesting how easy it is to get distracted and start
> reading about FCF, ONS, FAN and the like. I have two points that I
> think are specific to TAF and would appreciate clarification from
> those that have used these things in Real Life(tm).
> 1) The MAA documentation sets constantly refers to using both RAC and
> DG for HA.Yet only in a very few places do I see TAF configurations
> utilizing both RAC and DG. For example, here is snippet from "Client
> Failover Best Practices for Highly Available Oracle Databases: Oracle
> Database 10g Release 2
> SALESOCI =
> (DESCRIPTION =
> (ADDRESS_LIST =
> (ADDRESS = (PROTOCOL = TCP)(HOST = BOSTON1)(PORT = 1521))
> (ADDRESS = (PROTOCOL = TCP)(HOST = BOSTON2)(PORT = 1521))
> (ADDRESS = (PROTOCOL = TCP)(HOST = CHICAGO1)(PORT = 1521))
> (ADDRESS = (PROTOCOL = TCP)(HOST = CHICAGO2)(PORT = 1521))
> (LOAD_BALANCE = yes)
> Additionally, in other bodies of work I very rarely see this
> combination. I am curious, if this is a "Best Practice", how come it
> is not more widely used? Surely this is not that new (while the
> whitepaper cited above is from March of 2009, the features are from
> Oracle 10gR2). Are folks using this type of connection string in Real
> Life, to not only go between nodes in one cluster, but also to
> "failover" to standby nodes? Note that in the quoted example, this is
> */not/* a stretch cluster (between Chicago and Boston! Wow!), but
> rather a Primary/Standby environment.
> 2) Similar to this, I am trying to understand the different TAF
> parameters used in dbms_service.create_service
> The documentation has very little to say about them (just the bare
> bones - the 11g documentation
> is exactly the same I think), and when one implicitly creates a
> service by modifying the SERVICE_NAMES parameter, all the parameters
> default to null (according to dba_services). Are those TAF parameters
> actually used, or are they merely place-holders for "future"
> functionality? If they do play a role in TAF, what and how?
> Thanks for your time and help.
> Charles Schultz