RE: RAC Node Preference for sessions

  • From: <Christopher.Taylor2@xxxxxxxxxxxx>
  • To: <fmhabash@xxxxxxxxx>
  • Date: Sat, 2 Feb 2013 18:39:28 -0600

Good questions.

RAC 10.2.0.4 so using VIPs.  Client TNSNAMES looks correct.

Registration occurs via LOCAL_LISTENER (listener name) and REMOTE_LISTENER = 
RAC_LISTENER.

Your #3 is interesting.

I hadn't considered looking at the existing sessions - I was only thinking 
about load.  It's possible that the session counts are more balanced than I 
thought because we have lots of idle sessions.

We also have a lot of sessions end up in SNIPED status so I'm working on a cron 
job to clean those up - could be related?

Chris


-----Original Message-----
From: Fm [mailto:fmhabash@xxxxxxxxx] 
Sent: Saturday, February 02, 2013 6:25 PM
To: Taylor Christopher - Nashville
Cc: <oracle-l@xxxxxxxxxxxxx>
Subject: Re: RAC Node Preference for sessions

1) How are your instances registering with RAC listeners?
2) How are your clients connecting, VIP's or scan? How is the client tnsnames 
look like?
3) is session count similar across all instances irrespective of load?


---------------
Thank you. 

On Feb 2, 2013, at 1:32 PM, <Christopher.Taylor2@xxxxxxxxxxxx> wrote:

> Is there a way to influence [thru manual intervention] which node is 
> preferred for sessions?
> The reason I ask this question, in this way, is that we have 3 nodes, and 
> node 2 continuously seems to be favored for new sessions.
> 
> These are identical servers (DELL R900s) with the same OS, the same server 
> characteristics (CPU speeds etc).
> 
> We have the default RAC listener service configured:
> 
> SERVICE_ID      NAME    NAME_HASH       NETWORK_NAME    CREATION_DATE   
> CREATION_DATE_HASH      FAILOVER_METHOD FAILOVER_TYPE   FAILOVER_RETRIES      
>   FAILOVER_DELAY  MIN_CARDINALITY MAX_CARDINALITY GOAL    DTP     ENABLED 
> AQ_HA_NOTIFICATIONS     CLB_GOAL
> 3       CCMNASP1        2295827025      CCMNASP1        5/12/2010 1:58:52 PM  
>   2134570705                                                              N   
>     NO      NO      LONG
> 
> As an example, we had 2 nodes idling (1 & 3) and I was running a perf test on 
> node2 generating a lot of IO (but little CPU) and we kicked off some web 
> reports and they connected to node2 (from Business Objects server).
> 
> I have verified that the BOBJ server is set to use the CCMNASP1 network name 
> so I know it's not setup to only connect to the instance name on node2.
> 
> Part of the issue is that node2 is having "issues" of its own - so when it 
> gets loaded, the issues get exasperated.
> 
> I'm wondering what I'm overlooking (if anything).
> 
> 
> Chris Taylor
> Oracle DBA
> Parallon IT&S
> 
> 
> 
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> //www.freelists.org/webpage/oracle-l
> 
> 
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