Re: Regarding RAC vip failover and tnsnames entry

From: Riyaj Shamsudeen <riyaj.shamsudeen_at_gmail.com>
Date: Mon, 11 May 2009 13:47:58 -0500
Message-ID: <203315c10905111147u40946aaby1d03ef4ba07290d8_at_mail.gmail.com>

As Niall pointed out, OP is running active/passive nodes. So, he needs to have two addresses in that tnsnames entry and more importantly, load_balance switched off.

If connection time load balance is on, then one of the address is psuedo randomly chosen, which is probably not preferred in OP's case. He needs to have both addresses in that tnsnames string, load balance switched off and failover switched on.

Cheers

Riyaj Shamsudeen
Principal DBA,
Ora!nternals - http://www.orainternals.com Specialists in Performance, Recovery and EBS11i Blog: http://orainternals.wordpress.com

On Mon, May 11, 2009 at 1:33 PM, Niall Litchfield < niall.litchfield_at_gmail.com> wrote:

> And to add a bit. The OP described using RAC effectively to mimic an
> active/passive cluster. There are cheaper and better solutions for
> that.
>
> On 5/11/09, Bradd Piontek <piontekdd_at_gmail.com> wrote:
> > Not to sound contradictory (although I am contradicting what Riyaj
> wrote),
> > but the 2nd node is note 'required' to be in the tnsnames.ora if
> Server-Side
> > Load balancing is in place and you are using the VIP address. All
> listeners
> > on all nodes know of the other listeners, and can re-route traffic to a
> > different node. What is required is that the DNS entry spit back to the
> > client from the listener needs to be able to be resolved by the client.
> > As with just about anything, especially with RAC, it is important that
> you
> > test out all these types of scenarios and see how your application reacts
> to
> > these types of events. (regardless of what the manual says 'should'
> > happen). Just $0.02.
> >
> >
> > Bradd Piontek
> > "Next to doing a good job yourself,
> > the greatest joy is in having someone
> > else do a first-class job under your
> > direction."
> > -- William Feather
> >
> >
> > On Mon, May 11, 2009 at 12:53 PM, Riyaj Shamsudeen <
> > riyaj.shamsudeen_at_gmail.com> wrote:
> >
> >> Hi Sanjeev
> >>
> >> >> Is it required to have second node entry in tnsnanames.ora for
> >> connection to work
> >> >> after vip failover.
> >> Yes, you need to have second node entry also in your tnsnames.ora file.
> >>
> >> You might want to understand what problems VIPs are resolving. Let's say
> >> that a new connection request is made and for some reason IP address in
> >> that
> >> tnsnames entry is not available and so, there is no response from that
> IP.
> >> Connection request will wait for TCP connect timeout parameters
> (typically
> >> 3-10 minutes controlled by tcp parameters), then try next entry in the
> >> tnsnames list.
> >>
> >> By failing over VIP to surviving nodes of the cluster, there will be an
> >> immediate response, essentially as, 'no listener'. So, connection
> request
> >> will try next entry in the tnsnames entry immediately avoiding tcp
> connect
> >> timeout delays.
> >>
> >> HTH
> >>
> >> Cheers
> >>
> >> Riyaj Shamsudeen
> >> Principal DBA,
> >> Ora!nternals - http://www.orainternals.com
> >> Specialists in Performance, Recovery and EBS11i
> >> Blog: http://orainternals.wordpress.com
> >>
> >>
> >>
> >> On Mon, May 11, 2009 at 12:08 PM, Syed Jaffar Hussain <
> >> sjaffarhussain_at_gmail.com> wrote:
> >>
> >>> Sanjeev,
> >>> When a node fails, the VIP associated with failed node is automatically
> >>> fail over to one of other nodes exists in the cluster.
> >>>
> >>> The existing connections will typically receive ORA-3113 errors and the
> >>> new connections using address list will select the next entry in the
> >>> list.
> >>>
> >>>
> >>>
> >>> On Mon, May 11, 2009 at 9:39 AM, sanjeev m <sanjeevorcle_at_gmail.com
> >wrote:
> >>>
> >>>> All,
> >>>>
> >>>> We have two node RAC environment with the applications connections
> going
> >>>> to first node.
> >>>> (No reference to the second node in tnsnames.ora). We are not using
> load
> >>>> balancing or failover.
> >>>>
> >>>> If case of nic failure on first node CRS on the other node will
> failover
> >>>> the vip (raising event and bringing up the resource online on second
> >>>> node)
> >>>> and re-arp the machine address on the network.
> >>>>
> >>>> Question:
> >>>>
> >>>> (a) Existing connections: They will get an errors saying the instance
> is
> >>>> down.
> >>>> (b) New connections: They will be able to connect to vip on second
> node
> >>>> (with reference to firsthostname-vip entry in tnsnames.ora).
> >>>>
> >>>> Are both (a) and (b) true. Is it required to have second node entry in
> >>>> tnsnanames.ora for connection to work after vip failover.
> >>>>
> >>>> Regards
> >>>>
> >>>
> >>>
> >>>
> >>> --
> >>> Best Regards,
> >>>
> >>> Syed Jaffar Hussain
> >>> Oracle Certified Master (10g)
> >>> http://www.oracle.com/technology/ocm/shussain.html
> >>> Oracle ACE
> >>>
> >>>
> http://apex.oracle.com/pls/otn/f?p=19297:4:1579866181463918::NO:4:P4_ID:126
> >>> OCP 8i,9i & 10g DBA
> >>> RAC Certified Expert
> >>> Official Oracle RAC SIG Representative for Saudi Arabian region (
> >>> http://www.oracleracsig.org/)
> >>> I blog at
> >>> http://jaffardba.blogspot.com/
> >>> --------------------
> >>> "Winners don't do different things. They do things differently."
> >>>
> >>
> >>
> >
>
> --
> Sent from Google Mail for mobile | mobile.google.com
>
> Niall Litchfield
> Oracle DBA
> http://www.orawin.info
>

--
http://www.freelists.org/webpage/oracle-l

Received on Mon May 11 2009 - 13:47:58 CDT