RE: Cluster Interconnects configured in single-instance DB

  • From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxx>
  • To: Dan Norris <dannorris@xxxxxxxxxxxxx>
  • Date: Fri, 4 Apr 2008 13:58:00 -0400

Well, it's just a theory.  But I don't see why ASM traffic would have anything 
to do with the interconnect...?

I'm not currently able to test the theory, but maybe someone else can.

Personally, I'd expect a single instane db to be able to detect and connect to 
the local node of a clustered ASM installation....but maybe not....

I just don't know enough about the internal workings of ASM...

Mark J. Bobak
Senior Database Administrator, System & Product Technologies
789 E. Eisenhower, Parkway, P.O. Box 1346
Ann Arbor MI 48106-1346
+1.734.997.4059  or +1.800.521.0600 x 4059

ProQuest...Start here.

-----Original Message-----
From: Dan Norris [mailto:dannorris@xxxxxxxxxxxxx]
Sent: Friday, April 04, 2008 1:53 PM
To: Bobak, Mark
Cc: Jeffery Thomas; oracle-l
Subject: Re: Cluster Interconnects configured in single-instance DB


I'm not sure I agree with that theory.

When an instance uses ASM, part of the ASM codepath is executed by the
server process when accessing ASM. So, it makes some sense to me that
the RDBMS server would have some potential need to access the
interconnect when using ASM. I tend to agree with your (Jeff) theory
that it's got cluster interconnects defined because of the clustered ASM
interaction. That makes more sense to me than because of the binaries it
uses. I suppose the test would be to install a new O_H, do "make -f rac_off", then start up this DB using those binaries to see
what happens. My bet is that if you disable the RAC option and have
clustered ASM, you won't be able to start the instance, but I don't have
a suitable test environment to find out for sure. Hopefully someone does
or I'll have to build one and find out because now I have to know the
answer :).


Bobak, Mark wrote:
> Well, it can't be really *using* it, in the sense that it's got no other 
> nodes to talk to, but perhaps the RAC-aware binaries have a code path that 
> detects the interconnects (apparently by reading the OCR?) and lists them in 
> that V$ view?
> -----Original Message-----
> From: Jeffery Thomas [mailto:jeffthomas24@xxxxxxxxx]
> Sent: Friday, April 04, 2008 1:27 PM
> Subject: Re: Cluster Interconnects configured in single-instance DB
> Yes it does -- and in fact, I thought of that 5 seconds after I sent
> this email.     I guess then, it is actually *using* it?
> On Fri, Apr 4, 2008 at 1:18 PM, Bobak, Mark <Mark.Bobak@xxxxxxxxxxxx> wrote:
>> Hmm....does the single instance database use the same $ORACLE_HOME as the 
>> RAC database?
>>  -----Original Message-----
>>  From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] 
>> On Behalf Of Jeffery Thomas
>>  Sent: Friday, April 04, 2008 12:56 PM
>>  To: oracle-l
>>  Subject: Cluster Interconnects configured in single-instance DB
>>  We have a two-node RAC system on Solaris 10 using Oracle
>>  Clusterware and ASM that is being used for our test
>>  database..   We also have a single-instance database on one node of
>>  this cluster being used for development.
>>  The dev database is using  ASM, sharing the same data disk group as
>>  the RAC database.
>>  I noticed on startup in the alert.log that it is configuring
>>  interconnects; in addition, when I perform this query in the
>>  single-instance database:
>>  SQL> select * from v$cluster_interconnects;
>>  NAME            IP_ADDRESS       IS_ SOURCE
>>  --------------- ---------------- --- -------------------------------
>>  e1000g2    NO  Oracle Cluster Repository
>>  e1000g5    NO  Oracle Cluster Repository
>>  The question I have is:   why?     Is it because it is accessing a
>>  disk group maintained by a clustered ASM?
>>  Thanks,
>>  Jeff

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