Bradd--That's dead on for VIP functionality. As for TAF, it works
because of the black magic baked in to the SQL*Net client. Configure
the TNS connect descriptor as prescribed in the documentation and TAF
should function as advertised.
Technically, TAF doesn't require VIPs to be used. TAF can be used with
non-RAC databases too, though that's not common (multi-master rep is
the only case I've seen). Without VIPs, TAF just takes longer to work,
but as long as the timeouts are long enough, it should work either way.
One final note--TAF should use the VIPs provided by clusterware's
installation. You shouldn't have to create them, they'll be created as
part of the VIPCA run during installation. If you create a VIP, that
will be an application VIP and is intended for failover of a single
failover service (like a HTTP server or similar).
Dan
Bradd Piontek wrote:
The basic gist is this:
The VIP is a cluster resource managed by the clusterware. Depending
on your OS , you can see it running as a VIP under your public network
NIC. (ifconfig -a on Linux). What happens in a node failure is that the
clusterware brings that VIP resource up on another node so that when
clients attempt connects to that IP, the 'failure' is detected right
away and the client can use the next address in the tnsnames.ora entry
(or jdbc url, or whatever).
Try it out sometime. take a node node, use srvctl to see where the vips
are running and look at the ifconfig to see as well.
On Thu, Jul 10, 2008 at 8:30 AM, Dba DBA < oracledbaquestions@xxxxxxxxx>
wrote:
I
have installed Rac. I know how to create a VIP. I don't understand why
this works. I also don't undertsand why TAF works.
I am connected to node 1, how am I on the fly connected to node 2 if
node 1 goes down.
Again, I know the functionality, I just don't know how it works under
the covers.
Can anyone help me out with this?
--
Bradd Piontek
Twitter: http://www.twitter.com/piontekdd
Oracle Blog: http://piontekdd.blogspot.com
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